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  1.  
  2.  
  3.  
  4.  
  5.  
  6.  
  7. Network Working Group K. Murakami
  8. Request for Comments: 2173 M. Maruyama
  9. Category: Informational NTT Laboratories
  10. June 1997
  11.  
  12.  
  13. A MAPOS version 1 Extension - Node Switch Protocol
  14.  
  15. Status of this Memo
  16.  
  17. This memo provides information for the Internet community. This memo
  18. does not specify an Internet standard of any kind. Distribution of
  19. this memo is unlimited.
  20.  
  21. Abstract
  22.  
  23. This document describes a MAPOS extension, Node Switch Protocol, for
  24. automatic node address assignment. MAPOS is a multiple access
  25. protocol for transmission of network-protocol datagrams, encapsulated
  26. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  27. automates the HDLC address configuration of each node. Using NSP, a
  28. node retrieves its HDLC address from the switch to which it is
  29. connected.
  30.  
  31. 1. Introduction
  32.  
  33. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  34. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  35. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  36. switch provides multiple access capability to each node. In MAPOS,
  37. each node has a unique HDLC address within a switch. The address is
  38. equivalent to the port number of the switch to which the node is
  39. connected. This document describes an extension to MAPOS, Node
  40. Switch Protocol, which enable automatic HDLC address assignment.
  41. First, it explains the addressing of MAPOS. Then, it describes the
  42. NSP protocol for automatic HDLC node address assignment.
  43.  
  44. 2. Node Address Format
  45.  
  46. This section describes MAPOS Version 1 address format in single and
  47. multiple switch environment.
  48.  
  49.  
  50.  
  51.  
  52.  
  53.  
  54.  
  55.  
  56.  
  57.  
  58. Murakami & Maruyama Informational [Page 1]
  60. RFC 2173 MAPOS June 1997
  61.  
  62.  
  63. 2.1 Address Format
  64.  
  65. In MAPOS network, each end node has a unique HDLC address. As shown
  66. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  67. indicates the end of the field. When a SONET switch receives an HDLC
  68. frame, it forwards the frame based on the address in the frame
  69. header.
  70.  
  71. In unicast, MSB is 0 and the rest of the bits are the port number to
  72. which a node is connected. Since the LSB is always 1, the minimum and
  73. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  74. reserved and is assigned to the control processor in a SONET switch.
  75.  
  76. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  77. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  78. indicate the group address.
  79.  
  80. +-------------+-+
  81. | | | | | | | | |
  82. | |port number|1|
  83. +-+-----------+-+
  84. ^ ^
  85. | |
  86. | +------- EA bit (always 1)
  87. |
  88. 1 : broadcast, multicast
  89. 0 : unicast
  90.  
  91. Figure 1 Address format
  92.  
  93. 2.2 Address in multi-switch environment
  94.  
  95. In a multi-switch environment, variable-length subnet addressing is
  96. used. Each switch has a switch number that is unique within the
  97. system. Subnetted node addresses consist of the switch number and the
  98. port number to which a node is connected. The address format is "0
  99. <switch number> <node number> 1" for a unicast address, "all 1" for
  100. the broadcast address, and "1 <group address> 1" for a multicast
  101. address.
  102.  
  103. The address 0x01 is reserved and is assigned to the control processor
  104. in the "local" switch. That is, it indicates the switch itself to
  105. which the node is connected. The addresses of the form "0 <switch
  106. number> <all 0> 1" are reserved, and indicates the control processor
  107. of the switch designated by the switch number.
  108.  
  109. In Figure 2, the switch numbers are two bits long. Node N1 is
  110. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  111.  
  112.  
  113.  
  114. Murakami & Maruyama Informational [Page 2]
  116. RFC 2173 MAPOS June 1997
  117.  
  118.  
  119. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  120. has an address 01001001(0x49), since the switch number of S2 is 0x2
  121. (10 in binary) and the port number is 0x09. Note that all the port
  122. numbers are odd because the LSBs are always 1.
  123.  
  124. +------+
  125. | node |
  126. | N1 |
  127. +------+
  128. | 00100011(0x23)
  129. |
  130. |0x3 |0x3
  131. +------+ +---+----+ +---+----+ +------+
  132. | node +----+ SONET +-------+ SONET +-----+ node |
  133. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  134. +------+ | S1 | | S2 | +------+
  135. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  136. +---+----+ +---+----+
  137. |0x7 |0x7
  138.  
  139.  
  140. Figure 2 Addressing in Multiple Switch Environment
  141.  
  142. 4 NSP(Node-Switch Protocol)
  143.  
  144. This section describes the NSP protocol used for automatic node
  145. address assignment.
  146.  
  147. 4.1 NSP protocol
  148.  
  149. NSP is introduced to provide an automatic node address assignment
  150. function in MAPOS version 1. It reduces the administrative overhead
  151. of node address configuration for each node and prevents troubles
  152. such as address inconsistency and collision. When a node is connected
  153. to a switch and receives SONET signal correctly, the node sends an
  154. address request packet to the control processor in the local switch.
  155. The destination address of this packet is 00000001(0x01). When the
  156. control processor receives the packet, it replies with an address
  157. assignment packet. The destination is the assigned node address. If
  158. the node does not receive the address assignment packet within 5
  159. seconds, it retransmits the address request packet. The
  160. retransmission continues until the node successfully receives the
  161. address assignment packet.
  162.  
  163. Whenever a node detects a transmission error such as carrier loss or
  164. out-of-synchronization, it SHOULD send an address request packet to
  165. the control processor and verify its current address. In addition, a
  166. node MUST verify its address by sending address request packets every
  167.  
  168.  
  169.  
  170. Murakami & Maruyama Informational [Page 3]
  172. RFC 2173 MAPOS June 1997
  173.  
  174.  
  175. 30 seconds. The switch regards them as keep-alive packets and
  176. utilizes them to detect the node's status. If it has not received a
  177. request packet for more than 90 seconds, it assumes that the node
  178. went down. In addition, it also assumes the node went down when a
  179. switch detects a SONET signal failure.
  180.  
  181. 4.2 Packet Format
  182.  
  183. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  184. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  185. information field contains the NSP packet as shown in Figure 3.
  186.  
  187.  
  188. +-----------+------------+
  189. I command I address I
  190. +-----------+------------+
  191. I<- 32bit ->I<- 32 bit ->I
  192.  
  193. Figure 3 NSP packet format
  194.  
  195. The command field is 32 bits long and has the following values (in
  196. decimal);
  197.  
  198. 1 address request
  199. 2 address assignment
  200. 3 reject(error)
  201.  
  202. The length of the address field is 32bits. In address request
  203. packets, the NSP address field SHOULD be filled with zeroes, although
  204. the switch ignores it. In address assignment packets, the assigned
  205. address is placed in the least significant byte of the field. The
  206. rest of the field is padded with zeroes. When the switch can not
  207. assign the address for some reason, the switch replies with a reject
  208. command (the values is 3). The value of the address field is
  209. undefined.
  210.  
  211. 4.3 Consideration for special cases
  212.  
  213. There are two special cases to consider. One is a point-to-point
  214. connection without a switch. The other is loop-back, that is, direct
  215. connection between the input and the output of the same port.
  216.  
  217. 4.3.1 point-to-point
  218.  
  219. In the case of a point-to-point connection shown in Figure 4, a node
  220. sends an address request packet to the other node. The destination
  221. address is 00000001(0x01), that is usually a control processor in a
  222. switch. When a node receives the address request, it detects the
  223.  
  224.  
  225.  
  226. Murakami & Maruyama Informational [Page 4]
  228. RFC 2173 MAPOS June 1997
  229.  
  230.  
  231. point-to-point connection by examining both the destination address
  232. and the command contained. Then, it MUST reply with an address
  233. assignment packet. The assigned address MUST be 00000011(0x03). Since
  234. both nodes send an address request to each other, both of them get
  235. address 00000011(0x03). Since any address can be used in point-to-
  236. point environment, there is no problem even if both of the nodes have
  237. the same address.
  238.  
  239. ---- address request ----> 0x01
  240. 0x03 <---- address assignment ----
  241. +------+ +------+
  242. | node +--------------------------------+ node |
  243. +------+ +------+
  244. 0x01 <---- address request ----
  245. ---- address assignment ----> 0x03
  246.  
  247. Figure 4 Point-to-point connection
  248.  
  249. 4.3.2 loop-back
  250.  
  251. Another special case is loop-back where the output port of a node is
  252. simply connected to its input port as shown in Figure 5. In this
  253. case, the same mechanism as that for point-to-point can be applied
  254. without modification. A node sends an address request packet
  255. destined to 00000001(0x01). The node then receives the same packet.
  256. Since the destination is 00000001(0x01), it replies with an address
  257. assignment packet, containing the assigned address 00000011(0x03), to
  258. the address 0000 0011(0x03). Thus, the node obtains the address
  259. 00000011(0x03).
  260.  
  261. ---- address request ----> 0x01
  262. +------+ --- address assignment --> 0x03
  263. | +-------------->-----------------+
  264. | node + |
  265. | +--------------<-----------------+
  266. +------+
  267.  
  268. Figure 5 Loop-back Configuration
  269.  
  270.  
  271.  
  272.  
  273.  
  274.  
  275.  
  276.  
  277.  
  278.  
  279.  
  280.  
  281.  
  282. Murakami & Maruyama Informational [Page 5]
  284. RFC 2173 MAPOS June 1997
  285.  
  286.  
  287. 5. Security Considerations
  288.  
  289. Security issues are not discussed in this memo.
  290.  
  291. References
  292.  
  293. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  294. over SONET/SDH, Version 1," RFC-2171, June 1997.
  295.  
  296. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  297. Rates (1990).
  298.  
  299. [3] CCITT Recommendation G.708: Network Node Interface for
  300. Synchronous Digital Hierarchy (1990).
  301.  
  302. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  303. (1990).
  304.  
  305. [5] American National Standard for Telecommunications - Digital
  306. Hierarchy - Optical Interface Rates and Formats Specification,
  307. ANSI T1.105-1991.
  308.  
  309. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  310. Numbers," RFC-2172, June, 1997.
  311.  
  312. Acknowledgements
  313.  
  314. The authors would like to acknowledge the contributions and
  315. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  316. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  317.  
  318. Authors' Address
  319.  
  320. Ken Murakami
  321. NTT Software Laboratories
  322. 3-9-11, Midori-cho
  323. Musashino-shi
  324. Tokyo 180, Japan
  325. E-mail: murakami@ntt-20.ecl.net
  326.  
  327. Mitsuru Maruyama
  328. NTT Software Laboratories
  329. 3-9-11, Midori-cho
  330. Musashino-shi
  331. Tokyo 180, Japan
  332. E-mail: mitsuru@ntt-20.ecl.net
  333.  
  334.  
  335.  
  336.  
  337.  
  338. Murakami & Maruyama Informational [Page 6]
  339.  
  340.  
  341.  
  342.  
  343.  
  344.  
  345.  
  346. Network Working Group K. Murakami
  347. Request for Comments: 2173 M. Maruyama
  348. Category: Informational NTT Laboratories
  349. June 1997
  350.  
  351.  
  352. A MAPOS version 1 Extension - Node Switch Protocol
  353.  
  354. Status of this Memo
  355.  
  356. This memo provides information for the Internet community. This memo
  357. does not specify an Internet standard of any kind. Distribution of
  358. this memo is unlimited.
  359.  
  360. Abstract
  361.  
  362. This document describes a MAPOS extension, Node Switch Protocol, for
  363. automatic node address assignment. MAPOS is a multiple access
  364. protocol for transmission of network-protocol datagrams, encapsulated
  365. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  366. automates the HDLC address configuration of each node. Using NSP, a
  367. node retrieves its HDLC address from the switch to which it is
  368. connected.
  369.  
  370. 1. Introduction
  371.  
  372. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  373. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  374. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  375. switch provides multiple access capability to each node. In MAPOS,
  376. each node has a unique HDLC address within a switch. The address is
  377. equivalent to the port number of the switch to which the node is
  378. connected. This document describes an extension to MAPOS, Node
  379. Switch Protocol, which enable automatic HDLC address assignment.
  380. First, it explains the addressing of MAPOS. Then, it describes the
  381. NSP protocol for automatic HDLC node address assignment.
  382.  
  383. 2. Node Address Format
  384.  
  385. This section describes MAPOS Version 1 address format in single and
  386. multiple switch environment.
  387.  
  388.  
  389.  
  390.  
  391.  
  392.  
  393.  
  394.  
  395.  
  396.  
  397. Murakami & Maruyama Informational [Page 1]
  399. RFC 2173 MAPOS June 1997
  400.  
  401.  
  402. 2.1 Address Format
  403.  
  404. In MAPOS network, each end node has a unique HDLC address. As shown
  405. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  406. indicates the end of the field. When a SONET switch receives an HDLC
  407. frame, it forwards the frame based on the address in the frame
  408. header.
  409.  
  410. In unicast, MSB is 0 and the rest of the bits are the port number to
  411. which a node is connected. Since the LSB is always 1, the minimum and
  412. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  413. reserved and is assigned to the control processor in a SONET switch.
  414.  
  415. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  416. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  417. indicate the group address.
  418.  
  419. +-------------+-+
  420. | | | | | | | | |
  421. | |port number|1|
  422. +-+-----------+-+
  423. ^ ^
  424. | |
  425. | +------- EA bit (always 1)
  426. |
  427. 1 : broadcast, multicast
  428. 0 : unicast
  429.  
  430. Figure 1 Address format
  431.  
  432. 2.2 Address in multi-switch environment
  433.  
  434. In a multi-switch environment, variable-length subnet addressing is
  435. used. Each switch has a switch number that is unique within the
  436. system. Subnetted node addresses consist of the switch number and the
  437. port number to which a node is connected. The address format is "0
  438. <switch number> <node number> 1" for a unicast address, "all 1" for
  439. the broadcast address, and "1 <group address> 1" for a multicast
  440. address.
  441.  
  442. The address 0x01 is reserved and is assigned to the control processor
  443. in the "local" switch. That is, it indicates the switch itself to
  444. which the node is connected. The addresses of the form "0 <switch
  445. number> <all 0> 1" are reserved, and indicates the control processor
  446. of the switch designated by the switch number.
  447.  
  448. In Figure 2, the switch numbers are two bits long. Node N1 is
  449. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  450.  
  451.  
  452.  
  453. Murakami & Maruyama Informational [Page 2]
  455. RFC 2173 MAPOS June 1997
  456.  
  457.  
  458. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  459. has an address 01001001(0x49), since the switch number of S2 is 0x2
  460. (10 in binary) and the port number is 0x09. Note that all the port
  461. numbers are odd because the LSBs are always 1.
  462.  
  463. +------+
  464. | node |
  465. | N1 |
  466. +------+
  467. | 00100011(0x23)
  468. |
  469. |0x3 |0x3
  470. +------+ +---+----+ +---+----+ +------+
  471. | node +----+ SONET +-------+ SONET +-----+ node |
  472. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  473. +------+ | S1 | | S2 | +------+
  474. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  475. +---+----+ +---+----+
  476. |0x7 |0x7
  477.  
  478.  
  479. Figure 2 Addressing in Multiple Switch Environment
  480.  
  481. 4 NSP(Node-Switch Protocol)
  482.  
  483. This section describes the NSP protocol used for automatic node
  484. address assignment.
  485.  
  486. 4.1 NSP protocol
  487.  
  488. NSP is introduced to provide an automatic node address assignment
  489. function in MAPOS version 1. It reduces the administrative overhead
  490. of node address configuration for each node and prevents troubles
  491. such as address inconsistency and collision. When a node is connected
  492. to a switch and receives SONET signal correctly, the node sends an
  493. address request packet to the control processor in the local switch.
  494. The destination address of this packet is 00000001(0x01). When the
  495. control processor receives the packet, it replies with an address
  496. assignment packet. The destination is the assigned node address. If
  497. the node does not receive the address assignment packet within 5
  498. seconds, it retransmits the address request packet. The
  499. retransmission continues until the node successfully receives the
  500. address assignment packet.
  501.  
  502. Whenever a node detects a transmission error such as carrier loss or
  503. out-of-synchronization, it SHOULD send an address request packet to
  504. the control processor and verify its current address. In addition, a
  505. node MUST verify its address by sending address request packets every
  506.  
  507.  
  508.  
  509. Murakami & Maruyama Informational [Page 3]
  511. RFC 2173 MAPOS June 1997
  512.  
  513.  
  514. 30 seconds. The switch regards them as keep-alive packets and
  515. utilizes them to detect the node's status. If it has not received a
  516. request packet for more than 90 seconds, it assumes that the node
  517. went down. In addition, it also assumes the node went down when a
  518. switch detects a SONET signal failure.
  519.  
  520. 4.2 Packet Format
  521.  
  522. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  523. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  524. information field contains the NSP packet as shown in Figure 3.
  525.  
  526.  
  527. +-----------+------------+
  528. I command I address I
  529. +-----------+------------+
  530. I<- 32bit ->I<- 32 bit ->I
  531.  
  532. Figure 3 NSP packet format
  533.  
  534. The command field is 32 bits long and has the following values (in
  535. decimal);
  536.  
  537. 1 address request
  538. 2 address assignment
  539. 3 reject(error)
  540.  
  541. The length of the address field is 32bits. In address request
  542. packets, the NSP address field SHOULD be filled with zeroes, although
  543. the switch ignores it. In address assignment packets, the assigned
  544. address is placed in the least significant byte of the field. The
  545. rest of the field is padded with zeroes. When the switch can not
  546. assign the address for some reason, the switch replies with a reject
  547. command (the values is 3). The value of the address field is
  548. undefined.
  549.  
  550. 4.3 Consideration for special cases
  551.  
  552. There are two special cases to consider. One is a point-to-point
  553. connection without a switch. The other is loop-back, that is, direct
  554. connection between the input and the output of the same port.
  555.  
  556. 4.3.1 point-to-point
  557.  
  558. In the case of a point-to-point connection shown in Figure 4, a node
  559. sends an address request packet to the other node. The destination
  560. address is 00000001(0x01), that is usually a control processor in a
  561. switch. When a node receives the address request, it detects the
  562.  
  563.  
  564.  
  565. Murakami & Maruyama Informational [Page 4]
  567. RFC 2173 MAPOS June 1997
  568.  
  569.  
  570. point-to-point connection by examining both the destination address
  571. and the command contained. Then, it MUST reply with an address
  572. assignment packet. The assigned address MUST be 00000011(0x03). Since
  573. both nodes send an address request to each other, both of them get
  574. address 00000011(0x03). Since any address can be used in point-to-
  575. point environment, there is no problem even if both of the nodes have
  576. the same address.
  577.  
  578. ---- address request ----> 0x01
  579. 0x03 <---- address assignment ----
  580. +------+ +------+
  581. | node +--------------------------------+ node |
  582. +------+ +------+
  583. 0x01 <---- address request ----
  584. ---- address assignment ----> 0x03
  585.  
  586. Figure 4 Point-to-point connection
  587.  
  588. 4.3.2 loop-back
  589.  
  590. Another special case is loop-back where the output port of a node is
  591. simply connected to its input port as shown in Figure 5. In this
  592. case, the same mechanism as that for point-to-point can be applied
  593. without modification. A node sends an address request packet
  594. destined to 00000001(0x01). The node then receives the same packet.
  595. Since the destination is 00000001(0x01), it replies with an address
  596. assignment packet, containing the assigned address 00000011(0x03), to
  597. the address 0000 0011(0x03). Thus, the node obtains the address
  598. 00000011(0x03).
  599.  
  600. ---- address request ----> 0x01
  601. +------+ --- address assignment --> 0x03
  602. | +-------------->-----------------+
  603. | node + |
  604. | +--------------<-----------------+
  605. +------+
  606.  
  607. Figure 5 Loop-back Configuration
  608.  
  609.  
  610.  
  611.  
  612.  
  613.  
  614.  
  615.  
  616.  
  617.  
  618.  
  619.  
  620.  
  621. Murakami & Maruyama Informational [Page 5]
  623. RFC 2173 MAPOS June 1997
  624.  
  625.  
  626. 5. Security Considerations
  627.  
  628. Security issues are not discussed in this memo.
  629.  
  630. References
  631.  
  632. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  633. over SONET/SDH, Version 1," RFC-2171, June 1997.
  634.  
  635. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  636. Rates (1990).
  637.  
  638. [3] CCITT Recommendation G.708: Network Node Interface for
  639. Synchronous Digital Hierarchy (1990).
  640.  
  641. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  642. (1990).
  643.  
  644. [5] American National Standard for Telecommunications - Digital
  645. Hierarchy - Optical Interface Rates and Formats Specification,
  646. ANSI T1.105-1991.
  647.  
  648. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  649. Numbers," RFC-2172, June, 1997.
  650.  
  651. Acknowledgements
  652.  
  653. The authors would like to acknowledge the contributions and
  654. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  655. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  656.  
  657. Authors' Address
  658.  
  659. Ken Murakami
  660. NTT Software Laboratories
  661. 3-9-11, Midori-cho
  662. Musashino-shi
  663. Tokyo 180, Japan
  664. E-mail: murakami@ntt-20.ecl.net
  665.  
  666. Mitsuru Maruyama
  667. NTT Software Laboratories
  668. 3-9-11, Midori-cho
  669. Musashino-shi
  670. Tokyo 180, Japan
  671. E-mail: mitsuru@ntt-20.ecl.net
  672.  
  673.  
  674.  
  675.  
  676.  
  677. Murakami & Maruyama Informational [Page 6]
  679.  
  680.  
  681.  
  682.  
  683.  
  684.  
  685.  
  686. Network Working Group K. Murakami
  687. Request for Comments: 2173 M. Maruyama
  688. Category: Informational NTT Laboratories
  689. June 1997
  690.  
  691.  
  692. A MAPOS version 1 Extension - Node Switch Protocol
  693.  
  694. Status of this Memo
  695.  
  696. This memo provides information for the Internet community. This memo
  697. does not specify an Internet standard of any kind. Distribution of
  698. this memo is unlimited.
  699.  
  700. Abstract
  701.  
  702. This document describes a MAPOS extension, Node Switch Protocol, for
  703. automatic node address assignment. MAPOS is a multiple access
  704. protocol for transmission of network-protocol datagrams, encapsulated
  705. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  706. automates the HDLC address configuration of each node. Using NSP, a
  707. node retrieves its HDLC address from the switch to which it is
  708. connected.
  709.  
  710. 1. Introduction
  711.  
  712. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  713. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  714. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  715. switch provides multiple access capability to each node. In MAPOS,
  716. each node has a unique HDLC address within a switch. The address is
  717. equivalent to the port number of the switch to which the node is
  718. connected. This document describes an extension to MAPOS, Node
  719. Switch Protocol, which enable automatic HDLC address assignment.
  720. First, it explains the addressing of MAPOS. Then, it describes the
  721. NSP protocol for automatic HDLC node address assignment.
  722.  
  723. 2. Node Address Format
  724.  
  725. This section describes MAPOS Version 1 address format in single and
  726. multiple switch environment.
  727.  
  728.  
  729.  
  730.  
  731.  
  732.  
  733.  
  734.  
  735.  
  736.  
  737. Murakami & Maruyama Informational [Page 1]
  739. RFC 2173 MAPOS June 1997
  740.  
  741.  
  742. 2.1 Address Format
  743.  
  744. In MAPOS network, each end node has a unique HDLC address. As shown
  745. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  746. indicates the end of the field. When a SONET switch receives an HDLC
  747. frame, it forwards the frame based on the address in the frame
  748. header.
  749.  
  750. In unicast, MSB is 0 and the rest of the bits are the port number to
  751. which a node is connected. Since the LSB is always 1, the minimum and
  752. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  753. reserved and is assigned to the control processor in a SONET switch.
  754.  
  755. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  756. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  757. indicate the group address.
  758.  
  759. +-------------+-+
  760. | | | | | | | | |
  761. | |port number|1|
  762. +-+-----------+-+
  763. ^ ^
  764. | |
  765. | +------- EA bit (always 1)
  766. |
  767. 1 : broadcast, multicast
  768. 0 : unicast
  769.  
  770. Figure 1 Address format
  771.  
  772. 2.2 Address in multi-switch environment
  773.  
  774. In a multi-switch environment, variable-length subnet addressing is
  775. used. Each switch has a switch number that is unique within the
  776. system. Subnetted node addresses consist of the switch number and the
  777. port number to which a node is connected. The address format is "0
  778. <switch number> <node number> 1" for a unicast address, "all 1" for
  779. the broadcast address, and "1 <group address> 1" for a multicast
  780. address.
  781.  
  782. The address 0x01 is reserved and is assigned to the control processor
  783. in the "local" switch. That is, it indicates the switch itself to
  784. which the node is connected. The addresses of the form "0 <switch
  785. number> <all 0> 1" are reserved, and indicates the control processor
  786. of the switch designated by the switch number.
  787.  
  788. In Figure 2, the switch numbers are two bits long. Node N1 is
  789. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  790.  
  791.  
  792.  
  793. Murakami & Maruyama Informational [Page 2]
  795. RFC 2173 MAPOS June 1997
  796.  
  797.  
  798. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  799. has an address 01001001(0x49), since the switch number of S2 is 0x2
  800. (10 in binary) and the port number is 0x09. Note that all the port
  801. numbers are odd because the LSBs are always 1.
  802.  
  803. +------+
  804. | node |
  805. | N1 |
  806. +------+
  807. | 00100011(0x23)
  808. |
  809. |0x3 |0x3
  810. +------+ +---+----+ +---+----+ +------+
  811. | node +----+ SONET +-------+ SONET +-----+ node |
  812. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  813. +------+ | S1 | | S2 | +------+
  814. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  815. +---+----+ +---+----+
  816. |0x7 |0x7
  817.  
  818.  
  819. Figure 2 Addressing in Multiple Switch Environment
  820.  
  821. 4 NSP(Node-Switch Protocol)
  822.  
  823. This section describes the NSP protocol used for automatic node
  824. address assignment.
  825.  
  826. 4.1 NSP protocol
  827.  
  828. NSP is introduced to provide an automatic node address assignment
  829. function in MAPOS version 1. It reduces the administrative overhead
  830. of node address configuration for each node and prevents troubles
  831. such as address inconsistency and collision. When a node is connected
  832. to a switch and receives SONET signal correctly, the node sends an
  833. address request packet to the control processor in the local switch.
  834. The destination address of this packet is 00000001(0x01). When the
  835. control processor receives the packet, it replies with an address
  836. assignment packet. The destination is the assigned node address. If
  837. the node does not receive the address assignment packet within 5
  838. seconds, it retransmits the address request packet. The
  839. retransmission continues until the node successfully receives the
  840. address assignment packet.
  841.  
  842. Whenever a node detects a transmission error such as carrier loss or
  843. out-of-synchronization, it SHOULD send an address request packet to
  844. the control processor and verify its current address. In addition, a
  845. node MUST verify its address by sending address request packets every
  846.  
  847.  
  848.  
  849. Murakami & Maruyama Informational [Page 3]
  851. RFC 2173 MAPOS June 1997
  852.  
  853.  
  854. 30 seconds. The switch regards them as keep-alive packets and
  855. utilizes them to detect the node's status. If it has not received a
  856. request packet for more than 90 seconds, it assumes that the node
  857. went down. In addition, it also assumes the node went down when a
  858. switch detects a SONET signal failure.
  859.  
  860. 4.2 Packet Format
  861.  
  862. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  863. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  864. information field contains the NSP packet as shown in Figure 3.
  865.  
  866.  
  867. +-----------+------------+
  868. I command I address I
  869. +-----------+------------+
  870. I<- 32bit ->I<- 32 bit ->I
  871.  
  872. Figure 3 NSP packet format
  873.  
  874. The command field is 32 bits long and has the following values (in
  875. decimal);
  876.  
  877. 1 address request
  878. 2 address assignment
  879. 3 reject(error)
  880.  
  881. The length of the address field is 32bits. In address request
  882. packets, the NSP address field SHOULD be filled with zeroes, although
  883. the switch ignores it. In address assignment packets, the assigned
  884. address is placed in the least significant byte of the field. The
  885. rest of the field is padded with zeroes. When the switch can not
  886. assign the address for some reason, the switch replies with a reject
  887. command (the values is 3). The value of the address field is
  888. undefined.
  889.  
  890. 4.3 Consideration for special cases
  891.  
  892. There are two special cases to consider. One is a point-to-point
  893. connection without a switch. The other is loop-back, that is, direct
  894. connection between the input and the output of the same port.
  895.  
  896. 4.3.1 point-to-point
  897.  
  898. In the case of a point-to-point connection shown in Figure 4, a node
  899. sends an address request packet to the other node. The destination
  900. address is 00000001(0x01), that is usually a control processor in a
  901. switch. When a node receives the address request, it detects the
  902.  
  903.  
  904.  
  905. Murakami & Maruyama Informational [Page 4]
  907. RFC 2173 MAPOS June 1997
  908.  
  909.  
  910. point-to-point connection by examining both the destination address
  911. and the command contained. Then, it MUST reply with an address
  912. assignment packet. The assigned address MUST be 00000011(0x03). Since
  913. both nodes send an address request to each other, both of them get
  914. address 00000011(0x03). Since any address can be used in point-to-
  915. point environment, there is no problem even if both of the nodes have
  916. the same address.
  917.  
  918. ---- address request ----> 0x01
  919. 0x03 <---- address assignment ----
  920. +------+ +------+
  921. | node +--------------------------------+ node |
  922. +------+ +------+
  923. 0x01 <---- address request ----
  924. ---- address assignment ----> 0x03
  925.  
  926. Figure 4 Point-to-point connection
  927.  
  928. 4.3.2 loop-back
  929.  
  930. Another special case is loop-back where the output port of a node is
  931. simply connected to its input port as shown in Figure 5. In this
  932. case, the same mechanism as that for point-to-point can be applied
  933. without modification. A node sends an address request packet
  934. destined to 00000001(0x01). The node then receives the same packet.
  935. Since the destination is 00000001(0x01), it replies with an address
  936. assignment packet, containing the assigned address 00000011(0x03), to
  937. the address 0000 0011(0x03). Thus, the node obtains the address
  938. 00000011(0x03).
  939.  
  940. ---- address request ----> 0x01
  941. +------+ --- address assignment --> 0x03
  942. | +-------------->-----------------+
  943. | node + |
  944. | +--------------<-----------------+
  945. +------+
  946.  
  947. Figure 5 Loop-back Configuration
  948.  
  949.  
  950.  
  951.  
  952.  
  953.  
  954.  
  955.  
  956.  
  957.  
  958.  
  959.  
  960.  
  961. Murakami & Maruyama Informational [Page 5]
  963. RFC 2173 MAPOS June 1997
  964.  
  965.  
  966. 5. Security Considerations
  967.  
  968. Security issues are not discussed in this memo.
  969.  
  970. References
  971.  
  972. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  973. over SONET/SDH, Version 1," RFC-2171, June 1997.
  974.  
  975. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  976. Rates (1990).
  977.  
  978. [3] CCITT Recommendation G.708: Network Node Interface for
  979. Synchronous Digital Hierarchy (1990).
  980.  
  981. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  982. (1990).
  983.  
  984. [5] American National Standard for Telecommunications - Digital
  985. Hierarchy - Optical Interface Rates and Formats Specification,
  986. ANSI T1.105-1991.
  987.  
  988. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  989. Numbers," RFC-2172, June, 1997.
  990.  
  991. Acknowledgements
  992.  
  993. The authors would like to acknowledge the contributions and
  994. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  995. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  996.  
  997. Authors' Address
  998.  
  999. Ken Murakami
  1000. NTT Software Laboratories
  1001. 3-9-11, Midori-cho
  1002. Musashino-shi
  1003. Tokyo 180, Japan
  1004. E-mail: murakami@ntt-20.ecl.net
  1005.  
  1006. Mitsuru Maruyama
  1007. NTT Software Laboratories
  1008. 3-9-11, Midori-cho
  1009. Musashino-shi
  1010. Tokyo 180, Japan
  1011. E-mail: mitsuru@ntt-20.ecl.net
  1012.  
  1013.  
  1014.  
  1015.  
  1016.  
  1017. Murakami & Maruyama Informational [Page 6]
  1019.  
  1020.  
  1021.  
  1022.  
  1023.  
  1024.  
  1025.  
  1026. Network Working Group K. Murakami
  1027. Request for Comments: 2173 M. Maruyama
  1028. Category: Informational NTT Laboratories
  1029. June 1997
  1030.  
  1031.  
  1032. A MAPOS version 1 Extension - Node Switch Protocol
  1033.  
  1034. Status of this Memo
  1035.  
  1036. This memo provides information for the Internet community. This memo
  1037. does not specify an Internet standard of any kind. Distribution of
  1038. this memo is unlimited.
  1039.  
  1040. Abstract
  1041.  
  1042. This document describes a MAPOS extension, Node Switch Protocol, for
  1043. automatic node address assignment. MAPOS is a multiple access
  1044. protocol for transmission of network-protocol datagrams, encapsulated
  1045. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  1046. automates the HDLC address configuration of each node. Using NSP, a
  1047. node retrieves its HDLC address from the switch to which it is
  1048. connected.
  1049.  
  1050. 1. Introduction
  1051.  
  1052. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  1053. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  1054. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  1055. switch provides multiple access capability to each node. In MAPOS,
  1056. each node has a unique HDLC address within a switch. The address is
  1057. equivalent to the port number of the switch to which the node is
  1058. connected. This document describes an extension to MAPOS, Node
  1059. Switch Protocol, which enable automatic HDLC address assignment.
  1060. First, it explains the addressing of MAPOS. Then, it describes the
  1061. NSP protocol for automatic HDLC node address assignment.
  1062.  
  1063. 2. Node Address Format
  1064.  
  1065. This section describes MAPOS Version 1 address format in single and
  1066. multiple switch environment.
  1067.  
  1068.  
  1069.  
  1070.  
  1071.  
  1072.  
  1073.  
  1074.  
  1075.  
  1076.  
  1077. Murakami & Maruyama Informational [Page 1]
  1079. RFC 2173 MAPOS June 1997
  1080.  
  1081.  
  1082. 2.1 Address Format
  1083.  
  1084. In MAPOS network, each end node has a unique HDLC address. As shown
  1085. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  1086. indicates the end of the field. When a SONET switch receives an HDLC
  1087. frame, it forwards the frame based on the address in the frame
  1088. header.
  1089.  
  1090. In unicast, MSB is 0 and the rest of the bits are the port number to
  1091. which a node is connected. Since the LSB is always 1, the minimum and
  1092. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  1093. reserved and is assigned to the control processor in a SONET switch.
  1094.  
  1095. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  1096. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  1097. indicate the group address.
  1098.  
  1099. +-------------+-+
  1100. | | | | | | | | |
  1101. | |port number|1|
  1102. +-+-----------+-+
  1103. ^ ^
  1104. | |
  1105. | +------- EA bit (always 1)
  1106. |
  1107. 1 : broadcast, multicast
  1108. 0 : unicast
  1109.  
  1110. Figure 1 Address format
  1111.  
  1112. 2.2 Address in multi-switch environment
  1113.  
  1114. In a multi-switch environment, variable-length subnet addressing is
  1115. used. Each switch has a switch number that is unique within the
  1116. system. Subnetted node addresses consist of the switch number and the
  1117. port number to which a node is connected. The address format is "0
  1118. <switch number> <node number> 1" for a unicast address, "all 1" for
  1119. the broadcast address, and "1 <group address> 1" for a multicast
  1120. address.
  1121.  
  1122. The address 0x01 is reserved and is assigned to the control processor
  1123. in the "local" switch. That is, it indicates the switch itself to
  1124. which the node is connected. The addresses of the form "0 <switch
  1125. number> <all 0> 1" are reserved, and indicates the control processor
  1126. of the switch designated by the switch number.
  1127.  
  1128. In Figure 2, the switch numbers are two bits long. Node N1 is
  1129. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  1130.  
  1131.  
  1132.  
  1133. Murakami & Maruyama Informational [Page 2]
  1135. RFC 2173 MAPOS June 1997
  1136.  
  1137.  
  1138. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  1139. has an address 01001001(0x49), since the switch number of S2 is 0x2
  1140. (10 in binary) and the port number is 0x09. Note that all the port
  1141. numbers are odd because the LSBs are always 1.
  1142.  
  1143. +------+
  1144. | node |
  1145. | N1 |
  1146. +------+
  1147. | 00100011(0x23)
  1148. |
  1149. |0x3 |0x3
  1150. +------+ +---+----+ +---+----+ +------+
  1151. | node +----+ SONET +-------+ SONET +-----+ node |
  1152. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  1153. +------+ | S1 | | S2 | +------+
  1154. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  1155. +---+----+ +---+----+
  1156. |0x7 |0x7
  1157.  
  1158.  
  1159. Figure 2 Addressing in Multiple Switch Environment
  1160.  
  1161. 4 NSP(Node-Switch Protocol)
  1162.  
  1163. This section describes the NSP protocol used for automatic node
  1164. address assignment.
  1165.  
  1166. 4.1 NSP protocol
  1167.  
  1168. NSP is introduced to provide an automatic node address assignment
  1169. function in MAPOS version 1. It reduces the administrative overhead
  1170. of node address configuration for each node and prevents troubles
  1171. such as address inconsistency and collision. When a node is connected
  1172. to a switch and receives SONET signal correctly, the node sends an
  1173. address request packet to the control processor in the local switch.
  1174. The destination address of this packet is 00000001(0x01). When the
  1175. control processor receives the packet, it replies with an address
  1176. assignment packet. The destination is the assigned node address. If
  1177. the node does not receive the address assignment packet within 5
  1178. seconds, it retransmits the address request packet. The
  1179. retransmission continues until the node successfully receives the
  1180. address assignment packet.
  1181.  
  1182. Whenever a node detects a transmission error such as carrier loss or
  1183. out-of-synchronization, it SHOULD send an address request packet to
  1184. the control processor and verify its current address. In addition, a
  1185. node MUST verify its address by sending address request packets every
  1186.  
  1187.  
  1188.  
  1189. Murakami & Maruyama Informational [Page 3]
  1191. RFC 2173 MAPOS June 1997
  1192.  
  1193.  
  1194. 30 seconds. The switch regards them as keep-alive packets and
  1195. utilizes them to detect the node's status. If it has not received a
  1196. request packet for more than 90 seconds, it assumes that the node
  1197. went down. In addition, it also assumes the node went down when a
  1198. switch detects a SONET signal failure.
  1199.  
  1200. 4.2 Packet Format
  1201.  
  1202. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  1203. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  1204. information field contains the NSP packet as shown in Figure 3.
  1205.  
  1206.  
  1207. +-----------+------------+
  1208. I command I address I
  1209. +-----------+------------+
  1210. I<- 32bit ->I<- 32 bit ->I
  1211.  
  1212. Figure 3 NSP packet format
  1213.  
  1214. The command field is 32 bits long and has the following values (in
  1215. decimal);
  1216.  
  1217. 1 address request
  1218. 2 address assignment
  1219. 3 reject(error)
  1220.  
  1221. The length of the address field is 32bits. In address request
  1222. packets, the NSP address field SHOULD be filled with zeroes, although
  1223. the switch ignores it. In address assignment packets, the assigned
  1224. address is placed in the least significant byte of the field. The
  1225. rest of the field is padded with zeroes. When the switch can not
  1226. assign the address for some reason, the switch replies with a reject
  1227. command (the values is 3). The value of the address field is
  1228. undefined.
  1229.  
  1230. 4.3 Consideration for special cases
  1231.  
  1232. There are two special cases to consider. One is a point-to-point
  1233. connection without a switch. The other is loop-back, that is, direct
  1234. connection between the input and the output of the same port.
  1235.  
  1236. 4.3.1 point-to-point
  1237.  
  1238. In the case of a point-to-point connection shown in Figure 4, a node
  1239. sends an address request packet to the other node. The destination
  1240. address is 00000001(0x01), that is usually a control processor in a
  1241. switch. When a node receives the address request, it detects the
  1242.  
  1243.  
  1244.  
  1245. Murakami & Maruyama Informational [Page 4]
  1247. RFC 2173 MAPOS June 1997
  1248.  
  1249.  
  1250. point-to-point connection by examining both the destination address
  1251. and the command contained. Then, it MUST reply with an address
  1252. assignment packet. The assigned address MUST be 00000011(0x03). Since
  1253. both nodes send an address request to each other, both of them get
  1254. address 00000011(0x03). Since any address can be used in point-to-
  1255. point environment, there is no problem even if both of the nodes have
  1256. the same address.
  1257.  
  1258. ---- address request ----> 0x01
  1259. 0x03 <---- address assignment ----
  1260. +------+ +------+
  1261. | node +--------------------------------+ node |
  1262. +------+ +------+
  1263. 0x01 <---- address request ----
  1264. ---- address assignment ----> 0x03
  1265.  
  1266. Figure 4 Point-to-point connection
  1267.  
  1268. 4.3.2 loop-back
  1269.  
  1270. Another special case is loop-back where the output port of a node is
  1271. simply connected to its input port as shown in Figure 5. In this
  1272. case, the same mechanism as that for point-to-point can be applied
  1273. without modification. A node sends an address request packet
  1274. destined to 00000001(0x01). The node then receives the same packet.
  1275. Since the destination is 00000001(0x01), it replies with an address
  1276. assignment packet, containing the assigned address 00000011(0x03), to
  1277. the address 0000 0011(0x03). Thus, the node obtains the address
  1278. 00000011(0x03).
  1279.  
  1280. ---- address request ----> 0x01
  1281. +------+ --- address assignment --> 0x03
  1282. | +-------------->-----------------+
  1283. | node + |
  1284. | +--------------<-----------------+
  1285. +------+
  1286.  
  1287. Figure 5 Loop-back Configuration
  1288.  
  1289.  
  1290.  
  1291.  
  1292.  
  1293.  
  1294.  
  1295.  
  1296.  
  1297.  
  1298.  
  1299.  
  1300.  
  1301. Murakami & Maruyama Informational [Page 5]
  1303. RFC 2173 MAPOS June 1997
  1304.  
  1305.  
  1306. 5. Security Considerations
  1307.  
  1308. Security issues are not discussed in this memo.
  1309.  
  1310. References
  1311.  
  1312. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  1313. over SONET/SDH, Version 1," RFC-2171, June 1997.
  1314.  
  1315. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  1316. Rates (1990).
  1317.  
  1318. [3] CCITT Recommendation G.708: Network Node Interface for
  1319. Synchronous Digital Hierarchy (1990).
  1320.  
  1321. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  1322. (1990).
  1323.  
  1324. [5] American National Standard for Telecommunications - Digital
  1325. Hierarchy - Optical Interface Rates and Formats Specification,
  1326. ANSI T1.105-1991.
  1327.  
  1328. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  1329. Numbers," RFC-2172, June, 1997.
  1330.  
  1331. Acknowledgements
  1332.  
  1333. The authors would like to acknowledge the contributions and
  1334. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  1335. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  1336.  
  1337. Authors' Address
  1338.  
  1339. Ken Murakami
  1340. NTT Software Laboratories
  1341. 3-9-11, Midori-cho
  1342. Musashino-shi
  1343. Tokyo 180, Japan
  1344. E-mail: murakami@ntt-20.ecl.net
  1345.  
  1346. Mitsuru Maruyama
  1347. NTT Software Laboratories
  1348. 3-9-11, Midori-cho
  1349. Musashino-shi
  1350. Tokyo 180, Japan
  1351. E-mail: mitsuru@ntt-20.ecl.net
  1352.  
  1353.  
  1354.  
  1355.  
  1356.  
  1357. Murakami & Maruyama Informational [Page 6]
  1359.  
  1360.  
  1361.  
  1362.  
  1363.  
  1364.  
  1365.  
  1366. Network Working Group K. Murakami
  1367. Request for Comments: 2173 M. Maruyama
  1368. Category: Informational NTT Laboratories
  1369. June 1997
  1370.  
  1371.  
  1372. A MAPOS version 1 Extension - Node Switch Protocol
  1373.  
  1374. Status of this Memo
  1375.  
  1376. This memo provides information for the Internet community. This memo
  1377. does not specify an Internet standard of any kind. Distribution of
  1378. this memo is unlimited.
  1379.  
  1380. Abstract
  1381.  
  1382. This document describes a MAPOS extension, Node Switch Protocol, for
  1383. automatic node address assignment. MAPOS is a multiple access
  1384. protocol for transmission of network-protocol datagrams, encapsulated
  1385. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  1386. automates the HDLC address configuration of each node. Using NSP, a
  1387. node retrieves its HDLC address from the switch to which it is
  1388. connected.
  1389.  
  1390. 1. Introduction
  1391.  
  1392. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  1393. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  1394. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  1395. switch provides multiple access capability to each node. In MAPOS,
  1396. each node has a unique HDLC address within a switch. The address is
  1397. equivalent to the port number of the switch to which the node is
  1398. connected. This document describes an extension to MAPOS, Node
  1399. Switch Protocol, which enable automatic HDLC address assignment.
  1400. First, it explains the addressing of MAPOS. Then, it describes the
  1401. NSP protocol for automatic HDLC node address assignment.
  1402.  
  1403. 2. Node Address Format
  1404.  
  1405. This section describes MAPOS Version 1 address format in single and
  1406. multiple switch environment.
  1407.  
  1408.  
  1409.  
  1410.  
  1411.  
  1412.  
  1413.  
  1414.  
  1415.  
  1416.  
  1417. Murakami & Maruyama Informational [Page 1]
  1419. RFC 2173 MAPOS June 1997
  1420.  
  1421.  
  1422. 2.1 Address Format
  1423.  
  1424. In MAPOS network, each end node has a unique HDLC address. As shown
  1425. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  1426. indicates the end of the field. When a SONET switch receives an HDLC
  1427. frame, it forwards the frame based on the address in the frame
  1428. header.
  1429.  
  1430. In unicast, MSB is 0 and the rest of the bits are the port number to
  1431. which a node is connected. Since the LSB is always 1, the minimum and
  1432. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  1433. reserved and is assigned to the control processor in a SONET switch.
  1434.  
  1435. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  1436. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  1437. indicate the group address.
  1438.  
  1439. +-------------+-+
  1440. | | | | | | | | |
  1441. | |port number|1|
  1442. +-+-----------+-+
  1443. ^ ^
  1444. | |
  1445. | +------- EA bit (always 1)
  1446. |
  1447. 1 : broadcast, multicast
  1448. 0 : unicast
  1449.  
  1450. Figure 1 Address format
  1451.  
  1452. 2.2 Address in multi-switch environment
  1453.  
  1454. In a multi-switch environment, variable-length subnet addressing is
  1455. used. Each switch has a switch number that is unique within the
  1456. system. Subnetted node addresses consist of the switch number and the
  1457. port number to which a node is connected. The address format is "0
  1458. <switch number> <node number> 1" for a unicast address, "all 1" for
  1459. the broadcast address, and "1 <group address> 1" for a multicast
  1460. address.
  1461.  
  1462. The address 0x01 is reserved and is assigned to the control processor
  1463. in the "local" switch. That is, it indicates the switch itself to
  1464. which the node is connected. The addresses of the form "0 <switch
  1465. number> <all 0> 1" are reserved, and indicates the control processor
  1466. of the switch designated by the switch number.
  1467.  
  1468. In Figure 2, the switch numbers are two bits long. Node N1 is
  1469. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  1470.  
  1471.  
  1472.  
  1473. Murakami & Maruyama Informational [Page 2]
  1475. RFC 2173 MAPOS June 1997
  1476.  
  1477.  
  1478. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  1479. has an address 01001001(0x49), since the switch number of S2 is 0x2
  1480. (10 in binary) and the port number is 0x09. Note that all the port
  1481. numbers are odd because the LSBs are always 1.
  1482.  
  1483. +------+
  1484. | node |
  1485. | N1 |
  1486. +------+
  1487. | 00100011(0x23)
  1488. |
  1489. |0x3 |0x3
  1490. +------+ +---+----+ +---+----+ +------+
  1491. | node +----+ SONET +-------+ SONET +-----+ node |
  1492. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  1493. +------+ | S1 | | S2 | +------+
  1494. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  1495. +---+----+ +---+----+
  1496. |0x7 |0x7
  1497.  
  1498.  
  1499. Figure 2 Addressing in Multiple Switch Environment
  1500.  
  1501. 4 NSP(Node-Switch Protocol)
  1502.  
  1503. This section describes the NSP protocol used for automatic node
  1504. address assignment.
  1505.  
  1506. 4.1 NSP protocol
  1507.  
  1508. NSP is introduced to provide an automatic node address assignment
  1509. function in MAPOS version 1. It reduces the administrative overhead
  1510. of node address configuration for each node and prevents troubles
  1511. such as address inconsistency and collision. When a node is connected
  1512. to a switch and receives SONET signal correctly, the node sends an
  1513. address request packet to the control processor in the local switch.
  1514. The destination address of this packet is 00000001(0x01). When the
  1515. control processor receives the packet, it replies with an address
  1516. assignment packet. The destination is the assigned node address. If
  1517. the node does not receive the address assignment packet within 5
  1518. seconds, it retransmits the address request packet. The
  1519. retransmission continues until the node successfully receives the
  1520. address assignment packet.
  1521.  
  1522. Whenever a node detects a transmission error such as carrier loss or
  1523. out-of-synchronization, it SHOULD send an address request packet to
  1524. the control processor and verify its current address. In addition, a
  1525. node MUST verify its address by sending address request packets every
  1526.  
  1527.  
  1528.  
  1529. Murakami & Maruyama Informational [Page 3]
  1531. RFC 2173 MAPOS June 1997
  1532.  
  1533.  
  1534. 30 seconds. The switch regards them as keep-alive packets and
  1535. utilizes them to detect the node's status. If it has not received a
  1536. request packet for more than 90 seconds, it assumes that the node
  1537. went down. In addition, it also assumes the node went down when a
  1538. switch detects a SONET signal failure.
  1539.  
  1540. 4.2 Packet Format
  1541.  
  1542. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  1543. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  1544. information field contains the NSP packet as shown in Figure 3.
  1545.  
  1546.  
  1547. +-----------+------------+
  1548. I command I address I
  1549. +-----------+------------+
  1550. I<- 32bit ->I<- 32 bit ->I
  1551.  
  1552. Figure 3 NSP packet format
  1553.  
  1554. The command field is 32 bits long and has the following values (in
  1555. decimal);
  1556.  
  1557. 1 address request
  1558. 2 address assignment
  1559. 3 reject(error)
  1560.  
  1561. The length of the address field is 32bits. In address request
  1562. packets, the NSP address field SHOULD be filled with zeroes, although
  1563. the switch ignores it. In address assignment packets, the assigned
  1564. address is placed in the least significant byte of the field. The
  1565. rest of the field is padded with zeroes. When the switch can not
  1566. assign the address for some reason, the switch replies with a reject
  1567. command (the values is 3). The value of the address field is
  1568. undefined.
  1569.  
  1570. 4.3 Consideration for special cases
  1571.  
  1572. There are two special cases to consider. One is a point-to-point
  1573. connection without a switch. The other is loop-back, that is, direct
  1574. connection between the input and the output of the same port.
  1575.  
  1576. 4.3.1 point-to-point
  1577.  
  1578. In the case of a point-to-point connection shown in Figure 4, a node
  1579. sends an address request packet to the other node. The destination
  1580. address is 00000001(0x01), that is usually a control processor in a
  1581. switch. When a node receives the address request, it detects the
  1582.  
  1583.  
  1584.  
  1585. Murakami & Maruyama Informational [Page 4]
  1587. RFC 2173 MAPOS June 1997
  1588.  
  1589.  
  1590. point-to-point connection by examining both the destination address
  1591. and the command contained. Then, it MUST reply with an address
  1592. assignment packet. The assigned address MUST be 00000011(0x03). Since
  1593. both nodes send an address request to each other, both of them get
  1594. address 00000011(0x03). Since any address can be used in point-to-
  1595. point environment, there is no problem even if both of the nodes have
  1596. the same address.
  1597.  
  1598. ---- address request ----> 0x01
  1599. 0x03 <---- address assignment ----
  1600. +------+ +------+
  1601. | node +--------------------------------+ node |
  1602. +------+ +------+
  1603. 0x01 <---- address request ----
  1604. ---- address assignment ----> 0x03
  1605.  
  1606. Figure 4 Point-to-point connection
  1607.  
  1608. 4.3.2 loop-back
  1609.  
  1610. Another special case is loop-back where the output port of a node is
  1611. simply connected to its input port as shown in Figure 5. In this
  1612. case, the same mechanism as that for point-to-point can be applied
  1613. without modification. A node sends an address request packet
  1614. destined to 00000001(0x01). The node then receives the same packet.
  1615. Since the destination is 00000001(0x01), it replies with an address
  1616. assignment packet, containing the assigned address 00000011(0x03), to
  1617. the address 0000 0011(0x03). Thus, the node obtains the address
  1618. 00000011(0x03).
  1619.  
  1620. ---- address request ----> 0x01
  1621. +------+ --- address assignment --> 0x03
  1622. | +-------------->-----------------+
  1623. | node + |
  1624. | +--------------<-----------------+
  1625. +------+
  1626.  
  1627. Figure 5 Loop-back Configuration
  1628.  
  1629.  
  1630.  
  1631.  
  1632.  
  1633.  
  1634.  
  1635.  
  1636.  
  1637.  
  1638.  
  1639.  
  1640.  
  1641. Murakami & Maruyama Informational [Page 5]
  1643. RFC 2173 MAPOS June 1997
  1644.  
  1645.  
  1646. 5. Security Considerations
  1647.  
  1648. Security issues are not discussed in this memo.
  1649.  
  1650. References
  1651.  
  1652. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  1653. over SONET/SDH, Version 1," RFC-2171, June 1997.
  1654.  
  1655. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  1656. Rates (1990).
  1657.  
  1658. [3] CCITT Recommendation G.708: Network Node Interface for
  1659. Synchronous Digital Hierarchy (1990).
  1660.  
  1661. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  1662. (1990).
  1663.  
  1664. [5] American National Standard for Telecommunications - Digital
  1665. Hierarchy - Optical Interface Rates and Formats Specification,
  1666. ANSI T1.105-1991.
  1667.  
  1668. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  1669. Numbers," RFC-2172, June, 1997.
  1670.  
  1671. Acknowledgements
  1672.  
  1673. The authors would like to acknowledge the contributions and
  1674. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  1675. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  1676.  
  1677. Authors' Address
  1678.  
  1679. Ken Murakami
  1680. NTT Software Laboratories
  1681. 3-9-11, Midori-cho
  1682. Musashino-shi
  1683. Tokyo 180, Japan
  1684. E-mail: murakami@ntt-20.ecl.net
  1685.  
  1686. Mitsuru Maruyama
  1687. NTT Software Laboratories
  1688. 3-9-11, Midori-cho
  1689. Musashino-shi
  1690. Tokyo 180, Japan
  1691. E-mail: mitsuru@ntt-20.ecl.net
  1692.  
  1693.  
  1694.  
  1695.  
  1696.  
  1697. Murakami & Maruyama Informational [Page 6]
  1699.  
  1700.  
  1701.  
  1702.  
  1703.  
  1704.  
  1705.  
  1706. Network Working Group K. Murakami
  1707. Request for Comments: 2173 M. Maruyama
  1708. Category: Informational NTT Laboratories
  1709. June 1997
  1710.  
  1711.  
  1712. A MAPOS version 1 Extension - Node Switch Protocol
  1713.  
  1714. Status of this Memo
  1715.  
  1716. This memo provides information for the Internet community. This memo
  1717. does not specify an Internet standard of any kind. Distribution of
  1718. this memo is unlimited.
  1719.  
  1720. Abstract
  1721.  
  1722. This document describes a MAPOS extension, Node Switch Protocol, for
  1723. automatic node address assignment. MAPOS is a multiple access
  1724. protocol for transmission of network-protocol datagrams, encapsulated
  1725. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  1726. automates the HDLC address configuration of each node. Using NSP, a
  1727. node retrieves its HDLC address from the switch to which it is
  1728. connected.
  1729.  
  1730. 1. Introduction
  1731.  
  1732. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  1733. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  1734. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  1735. switch provides multiple access capability to each node. In MAPOS,
  1736. each node has a unique HDLC address within a switch. The address is
  1737. equivalent to the port number of the switch to which the node is
  1738. connected. This document describes an extension to MAPOS, Node
  1739. Switch Protocol, which enable automatic HDLC address assignment.
  1740. First, it explains the addressing of MAPOS. Then, it describes the
  1741. NSP protocol for automatic HDLC node address assignment.
  1742.  
  1743. 2. Node Address Format
  1744.  
  1745. This section describes MAPOS Version 1 address format in single and
  1746. multiple switch environment.
  1747.  
  1748.  
  1749.  
  1750.  
  1751.  
  1752.  
  1753.  
  1754.  
  1755.  
  1756.  
  1757. Murakami & Maruyama Informational [Page 1]
  1759. RFC 2173 MAPOS June 1997
  1760.  
  1761.  
  1762. 2.1 Address Format
  1763.  
  1764. In MAPOS network, each end node has a unique HDLC address. As shown
  1765. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  1766. indicates the end of the field. When a SONET switch receives an HDLC
  1767. frame, it forwards the frame based on the address in the frame
  1768. header.
  1769.  
  1770. In unicast, MSB is 0 and the rest of the bits are the port number to
  1771. which a node is connected. Since the LSB is always 1, the minimum and
  1772. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  1773. reserved and is assigned to the control processor in a SONET switch.
  1774.  
  1775. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  1776. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  1777. indicate the group address.
  1778.  
  1779. +-------------+-+
  1780. | | | | | | | | |
  1781. | |port number|1|
  1782. +-+-----------+-+
  1783. ^ ^
  1784. | |
  1785. | +------- EA bit (always 1)
  1786. |
  1787. 1 : broadcast, multicast
  1788. 0 : unicast
  1789.  
  1790. Figure 1 Address format
  1791.  
  1792. 2.2 Address in multi-switch environment
  1793.  
  1794. In a multi-switch environment, variable-length subnet addressing is
  1795. used. Each switch has a switch number that is unique within the
  1796. system. Subnetted node addresses consist of the switch number and the
  1797. port number to which a node is connected. The address format is "0
  1798. <switch number> <node number> 1" for a unicast address, "all 1" for
  1799. the broadcast address, and "1 <group address> 1" for a multicast
  1800. address.
  1801.  
  1802. The address 0x01 is reserved and is assigned to the control processor
  1803. in the "local" switch. That is, it indicates the switch itself to
  1804. which the node is connected. The addresses of the form "0 <switch
  1805. number> <all 0> 1" are reserved, and indicates the control processor
  1806. of the switch designated by the switch number.
  1807.  
  1808. In Figure 2, the switch numbers are two bits long. Node N1 is
  1809. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  1810.  
  1811.  
  1812.  
  1813. Murakami & Maruyama Informational [Page 2]
  1815. RFC 2173 MAPOS June 1997
  1816.  
  1817.  
  1818. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  1819. has an address 01001001(0x49), since the switch number of S2 is 0x2
  1820. (10 in binary) and the port number is 0x09. Note that all the port
  1821. numbers are odd because the LSBs are always 1.
  1822.  
  1823. +------+
  1824. | node |
  1825. | N1 |
  1826. +------+
  1827. | 00100011(0x23)
  1828. |
  1829. |0x3 |0x3
  1830. +------+ +---+----+ +---+----+ +------+
  1831. | node +----+ SONET +-------+ SONET +-----+ node |
  1832. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  1833. +------+ | S1 | | S2 | +------+
  1834. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  1835. +---+----+ +---+----+
  1836. |0x7 |0x7
  1837.  
  1838.  
  1839. Figure 2 Addressing in Multiple Switch Environment
  1840.  
  1841. 4 NSP(Node-Switch Protocol)
  1842.  
  1843. This section describes the NSP protocol used for automatic node
  1844. address assignment.
  1845.  
  1846. 4.1 NSP protocol
  1847.  
  1848. NSP is introduced to provide an automatic node address assignment
  1849. function in MAPOS version 1. It reduces the administrative overhead
  1850. of node address configuration for each node and prevents troubles
  1851. such as address inconsistency and collision. When a node is connected
  1852. to a switch and receives SONET signal correctly, the node sends an
  1853. address request packet to the control processor in the local switch.
  1854. The destination address of this packet is 00000001(0x01). When the
  1855. control processor receives the packet, it replies with an address
  1856. assignment packet. The destination is the assigned node address. If
  1857. the node does not receive the address assignment packet within 5
  1858. seconds, it retransmits the address request packet. The
  1859. retransmission continues until the node successfully receives the
  1860. address assignment packet.
  1861.  
  1862. Whenever a node detects a transmission error such as carrier loss or
  1863. out-of-synchronization, it SHOULD send an address request packet to
  1864. the control processor and verify its current address. In addition, a
  1865. node MUST verify its address by sending address request packets every
  1866.  
  1867.  
  1868.  
  1869. Murakami & Maruyama Informational [Page 3]
  1871. RFC 2173 MAPOS June 1997
  1872.  
  1873.  
  1874. 30 seconds. The switch regards them as keep-alive packets and
  1875. utilizes them to detect the node's status. If it has not received a
  1876. request packet for more than 90 seconds, it assumes that the node
  1877. went down. In addition, it also assumes the node went down when a
  1878. switch detects a SONET signal failure.
  1879.  
  1880. 4.2 Packet Format
  1881.  
  1882. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  1883. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  1884. information field contains the NSP packet as shown in Figure 3.
  1885.  
  1886.  
  1887. +-----------+------------+
  1888. I command I address I
  1889. +-----------+------------+
  1890. I<- 32bit ->I<- 32 bit ->I
  1891.  
  1892. Figure 3 NSP packet format
  1893.  
  1894. The command field is 32 bits long and has the following values (in
  1895. decimal);
  1896.  
  1897. 1 address request
  1898. 2 address assignment
  1899. 3 reject(error)
  1900.  
  1901. The length of the address field is 32bits. In address request
  1902. packets, the NSP address field SHOULD be filled with zeroes, although
  1903. the switch ignores it. In address assignment packets, the assigned
  1904. address is placed in the least significant byte of the field. The
  1905. rest of the field is padded with zeroes. When the switch can not
  1906. assign the address for some reason, the switch replies with a reject
  1907. command (the values is 3). The value of the address field is
  1908. undefined.
  1909.  
  1910. 4.3 Consideration for special cases
  1911.  
  1912. There are two special cases to consider. One is a point-to-point
  1913. connection without a switch. The other is loop-back, that is, direct
  1914. connection between the input and the output of the same port.
  1915.  
  1916. 4.3.1 point-to-point
  1917.  
  1918. In the case of a point-to-point connection shown in Figure 4, a node
  1919. sends an address request packet to the other node. The destination
  1920. address is 00000001(0x01), that is usually a control processor in a
  1921. switch. When a node receives the address request, it detects the
  1922.  
  1923.  
  1924.  
  1925. Murakami & Maruyama Informational [Page 4]
  1927. RFC 2173 MAPOS June 1997
  1928.  
  1929.  
  1930. point-to-point connection by examining both the destination address
  1931. and the command contained. Then, it MUST reply with an address
  1932. assignment packet. The assigned address MUST be 00000011(0x03). Since
  1933. both nodes send an address request to each other, both of them get
  1934. address 00000011(0x03). Since any address can be used in point-to-
  1935. point environment, there is no problem even if both of the nodes have
  1936. the same address.
  1937.  
  1938. ---- address request ----> 0x01
  1939. 0x03 <---- address assignment ----
  1940. +------+ +------+
  1941. | node +--------------------------------+ node |
  1942. +------+ +------+
  1943. 0x01 <---- address request ----
  1944. ---- address assignment ----> 0x03
  1945.  
  1946. Figure 4 Point-to-point connection
  1947.  
  1948. 4.3.2 loop-back
  1949.  
  1950. Another special case is loop-back where the output port of a node is
  1951. simply connected to its input port as shown in Figure 5. In this
  1952. case, the same mechanism as that for point-to-point can be applied
  1953. without modification. A node sends an address request packet
  1954. destined to 00000001(0x01). The node then receives the same packet.
  1955. Since the destination is 00000001(0x01), it replies with an address
  1956. assignment packet, containing the assigned address 00000011(0x03), to
  1957. the address 0000 0011(0x03). Thus, the node obtains the address
  1958. 00000011(0x03).
  1959.  
  1960. ---- address request ----> 0x01
  1961. +------+ --- address assignment --> 0x03
  1962. | +-------------->-----------------+
  1963. | node + |
  1964. | +--------------<-----------------+
  1965. +------+
  1966.  
  1967. Figure 5 Loop-back Configuration
  1968.  
  1969.  
  1970.  
  1971.  
  1972.  
  1973.  
  1974.  
  1975.  
  1976.  
  1977.  
  1978.  
  1979.  
  1980.  
  1981. Murakami & Maruyama Informational [Page 5]
  1983. RFC 2173 MAPOS June 1997
  1984.  
  1985.  
  1986. 5. Security Considerations
  1987.  
  1988. Security issues are not discussed in this memo.
  1989.  
  1990. References
  1991.  
  1992. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  1993. over SONET/SDH, Version 1," RFC-2171, June 1997.
  1994.  
  1995. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  1996. Rates (1990).
  1997.  
  1998. [3] CCITT Recommendation G.708: Network Node Interface for
  1999. Synchronous Digital Hierarchy (1990).
  2000.  
  2001. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  2002. (1990).
  2003.  
  2004. [5] American National Standard for Telecommunications - Digital
  2005. Hierarchy - Optical Interface Rates and Formats Specification,
  2006. ANSI T1.105-1991.
  2007.  
  2008. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  2009. Numbers," RFC-2172, June, 1997.
  2010.  
  2011. Acknowledgements
  2012.  
  2013. The authors would like to acknowledge the contributions and
  2014. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  2015. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  2016.  
  2017. Authors' Address
  2018.  
  2019. Ken Murakami
  2020. NTT Software Laboratories
  2021. 3-9-11, Midori-cho
  2022. Musashino-shi
  2023. Tokyo 180, Japan
  2024. E-mail: murakami@ntt-20.ecl.net
  2025.  
  2026. Mitsuru Maruyama
  2027. NTT Software Laboratories
  2028. 3-9-11, Midori-cho
  2029. Musashino-shi
  2030. Tokyo 180, Japan
  2031. E-mail: mitsuru@ntt-20.ecl.net
  2032.  
  2033.  
  2034.  
  2035.  
  2036.  
  2037. Murakami & Maruyama Informational [Page 6]
  2039.  
  2040.  
  2041.  
  2042.  
  2043.  
  2044.  
  2045.  
  2046. Network Working Group K. Murakami
  2047. Request for Comments: 2173 M. Maruyama
  2048. Category: Informational NTT Laboratories
  2049. June 1997
  2050.  
  2051.  
  2052. A MAPOS version 1 Extension - Node Switch Protocol
  2053.  
  2054. Status of this Memo
  2055.  
  2056. This memo provides information for the Internet community. This memo
  2057. does not specify an Internet standard of any kind. Distribution of
  2058. this memo is unlimited.
  2059.  
  2060. Abstract
  2061.  
  2062. This document describes a MAPOS extension, Node Switch Protocol, for
  2063. automatic node address assignment. MAPOS is a multiple access
  2064. protocol for transmission of network-protocol datagrams, encapsulated
  2065. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  2066. automates the HDLC address configuration of each node. Using NSP, a
  2067. node retrieves its HDLC address from the switch to which it is
  2068. connected.
  2069.  
  2070. 1. Introduction
  2071.  
  2072. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  2073. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  2074. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  2075. switch provides multiple access capability to each node. In MAPOS,
  2076. each node has a unique HDLC address within a switch. The address is
  2077. equivalent to the port number of the switch to which the node is
  2078. connected. This document describes an extension to MAPOS, Node
  2079. Switch Protocol, which enable automatic HDLC address assignment.
  2080. First, it explains the addressing of MAPOS. Then, it describes the
  2081. NSP protocol for automatic HDLC node address assignment.
  2082.  
  2083. 2. Node Address Format
  2084.  
  2085. This section describes MAPOS Version 1 address format in single and
  2086. multiple switch environment.
  2087.  
  2088.  
  2089.  
  2090.  
  2091.  
  2092.  
  2093.  
  2094.  
  2095.  
  2096.  
  2097. Murakami & Maruyama Informational [Page 1]
  2099. RFC 2173 MAPOS June 1997
  2100.  
  2101.  
  2102. 2.1 Address Format
  2103.  
  2104. In MAPOS network, each end node has a unique HDLC address. As shown
  2105. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  2106. indicates the end of the field. When a SONET switch receives an HDLC
  2107. frame, it forwards the frame based on the address in the frame
  2108. header.
  2109.  
  2110. In unicast, MSB is 0 and the rest of the bits are the port number to
  2111. which a node is connected. Since the LSB is always 1, the minimum and
  2112. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  2113. reserved and is assigned to the control processor in a SONET switch.
  2114.  
  2115. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  2116. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  2117. indicate the group address.
  2118.  
  2119. +-------------+-+
  2120. | | | | | | | | |
  2121. | |port number|1|
  2122. +-+-----------+-+
  2123. ^ ^
  2124. | |
  2125. | +------- EA bit (always 1)
  2126. |
  2127. 1 : broadcast, multicast
  2128. 0 : unicast
  2129.  
  2130. Figure 1 Address format
  2131.  
  2132. 2.2 Address in multi-switch environment
  2133.  
  2134. In a multi-switch environment, variable-length subnet addressing is
  2135. used. Each switch has a switch number that is unique within the
  2136. system. Subnetted node addresses consist of the switch number and the
  2137. port number to which a node is connected. The address format is "0
  2138. <switch number> <node number> 1" for a unicast address, "all 1" for
  2139. the broadcast address, and "1 <group address> 1" for a multicast
  2140. address.
  2141.  
  2142. The address 0x01 is reserved and is assigned to the control processor
  2143. in the "local" switch. That is, it indicates the switch itself to
  2144. which the node is connected. The addresses of the form "0 <switch
  2145. number> <all 0> 1" are reserved, and indicates the control processor
  2146. of the switch designated by the switch number.
  2147.  
  2148. In Figure 2, the switch numbers are two bits long. Node N1 is
  2149. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  2150.  
  2151.  
  2152.  
  2153. Murakami & Maruyama Informational [Page 2]
  2155. RFC 2173 MAPOS June 1997
  2156.  
  2157.  
  2158. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  2159. has an address 01001001(0x49), since the switch number of S2 is 0x2
  2160. (10 in binary) and the port number is 0x09. Note that all the port
  2161. numbers are odd because the LSBs are always 1.
  2162.  
  2163. +------+
  2164. | node |
  2165. | N1 |
  2166. +------+
  2167. | 00100011(0x23)
  2168. |
  2169. |0x3 |0x3
  2170. +------+ +---+----+ +---+----+ +------+
  2171. | node +----+ SONET +-------+ SONET +-----+ node |
  2172. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  2173. +------+ | S1 | | S2 | +------+
  2174. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  2175. +---+----+ +---+----+
  2176. |0x7 |0x7
  2177.  
  2178.  
  2179. Figure 2 Addressing in Multiple Switch Environment
  2180.  
  2181. 4 NSP(Node-Switch Protocol)
  2182.  
  2183. This section describes the NSP protocol used for automatic node
  2184. address assignment.
  2185.  
  2186. 4.1 NSP protocol
  2187.  
  2188. NSP is introduced to provide an automatic node address assignment
  2189. function in MAPOS version 1. It reduces the administrative overhead
  2190. of node address configuration for each node and prevents troubles
  2191. such as address inconsistency and collision. When a node is connected
  2192. to a switch and receives SONET signal correctly, the node sends an
  2193. address request packet to the control processor in the local switch.
  2194. The destination address of this packet is 00000001(0x01). When the
  2195. control processor receives the packet, it replies with an address
  2196. assignment packet. The destination is the assigned node address. If
  2197. the node does not receive the address assignment packet within 5
  2198. seconds, it retransmits the address request packet. The
  2199. retransmission continues until the node successfully receives the
  2200. address assignment packet.
  2201.  
  2202. Whenever a node detects a transmission error such as carrier loss or
  2203. out-of-synchronization, it SHOULD send an address request packet to
  2204. the control processor and verify its current address. In addition, a
  2205. node MUST verify its address by sending address request packets every
  2206.  
  2207.  
  2208.  
  2209. Murakami & Maruyama Informational [Page 3]
  2211. RFC 2173 MAPOS June 1997
  2212.  
  2213.  
  2214. 30 seconds. The switch regards them as keep-alive packets and
  2215. utilizes them to detect the node's status. If it has not received a
  2216. request packet for more than 90 seconds, it assumes that the node
  2217. went down. In addition, it also assumes the node went down when a
  2218. switch detects a SONET signal failure.
  2219.  
  2220. 4.2 Packet Format
  2221.  
  2222. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  2223. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  2224. information field contains the NSP packet as shown in Figure 3.
  2225.  
  2226.  
  2227. +-----------+------------+
  2228. I command I address I
  2229. +-----------+------------+
  2230. I<- 32bit ->I<- 32 bit ->I
  2231.  
  2232. Figure 3 NSP packet format
  2233.  
  2234. The command field is 32 bits long and has the following values (in
  2235. decimal);
  2236.  
  2237. 1 address request
  2238. 2 address assignment
  2239. 3 reject(error)
  2240.  
  2241. The length of the address field is 32bits. In address request
  2242. packets, the NSP address field SHOULD be filled with zeroes, although
  2243. the switch ignores it. In address assignment packets, the assigned
  2244. address is placed in the least significant byte of the field. The
  2245. rest of the field is padded with zeroes. When the switch can not
  2246. assign the address for some reason, the switch replies with a reject
  2247. command (the values is 3). The value of the address field is
  2248. undefined.
  2249.  
  2250. 4.3 Consideration for special cases
  2251.  
  2252. There are two special cases to consider. One is a point-to-point
  2253. connection without a switch. The other is loop-back, that is, direct
  2254. connection between the input and the output of the same port.
  2255.  
  2256. 4.3.1 point-to-point
  2257.  
  2258. In the case of a point-to-point connection shown in Figure 4, a node
  2259. sends an address request packet to the other node. The destination
  2260. address is 00000001(0x01), that is usually a control processor in a
  2261. switch. When a node receives the address request, it detects the
  2262.  
  2263.  
  2264.  
  2265. Murakami & Maruyama Informational [Page 4]
  2267. RFC 2173 MAPOS June 1997
  2268.  
  2269.  
  2270. point-to-point connection by examining both the destination address
  2271. and the command contained. Then, it MUST reply with an address
  2272. assignment packet. The assigned address MUST be 00000011(0x03). Since
  2273. both nodes send an address request to each other, both of them get
  2274. address 00000011(0x03). Since any address can be used in point-to-
  2275. point environment, there is no problem even if both of the nodes have
  2276. the same address.
  2277.  
  2278. ---- address request ----> 0x01
  2279. 0x03 <---- address assignment ----
  2280. +------+ +------+
  2281. | node +--------------------------------+ node |
  2282. +------+ +------+
  2283. 0x01 <---- address request ----
  2284. ---- address assignment ----> 0x03
  2285.  
  2286. Figure 4 Point-to-point connection
  2287.  
  2288. 4.3.2 loop-back
  2289.  
  2290. Another special case is loop-back where the output port of a node is
  2291. simply connected to its input port as shown in Figure 5. In this
  2292. case, the same mechanism as that for point-to-point can be applied
  2293. without modification. A node sends an address request packet
  2294. destined to 00000001(0x01). The node then receives the same packet.
  2295. Since the destination is 00000001(0x01), it replies with an address
  2296. assignment packet, containing the assigned address 00000011(0x03), to
  2297. the address 0000 0011(0x03). Thus, the node obtains the address
  2298. 00000011(0x03).
  2299.  
  2300. ---- address request ----> 0x01
  2301. +------+ --- address assignment --> 0x03
  2302. | +-------------->-----------------+
  2303. | node + |
  2304. | +--------------<-----------------+
  2305. +------+
  2306.  
  2307. Figure 5 Loop-back Configuration
  2308.  
  2309.  
  2310.  
  2311.  
  2312.  
  2313.  
  2314.  
  2315.  
  2316.  
  2317.  
  2318.  
  2319.  
  2320.  
  2321. Murakami & Maruyama Informational [Page 5]
  2323. RFC 2173 MAPOS June 1997
  2324.  
  2325.  
  2326. 5. Security Considerations
  2327.  
  2328. Security issues are not discussed in this memo.
  2329.  
  2330. References
  2331.  
  2332. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  2333. over SONET/SDH, Version 1," RFC-2171, June 1997.
  2334.  
  2335. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  2336. Rates (1990).
  2337.  
  2338. [3] CCITT Recommendation G.708: Network Node Interface for
  2339. Synchronous Digital Hierarchy (1990).
  2340.  
  2341. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  2342. (1990).
  2343.  
  2344. [5] American National Standard for Telecommunications - Digital
  2345. Hierarchy - Optical Interface Rates and Formats Specification,
  2346. ANSI T1.105-1991.
  2347.  
  2348. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  2349. Numbers," RFC-2172, June, 1997.
  2350.  
  2351. Acknowledgements
  2352.  
  2353. The authors would like to acknowledge the contributions and
  2354. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  2355. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  2356.  
  2357. Authors' Address
  2358.  
  2359. Ken Murakami
  2360. NTT Software Laboratories
  2361. 3-9-11, Midori-cho
  2362. Musashino-shi
  2363. Tokyo 180, Japan
  2364. E-mail: murakami@ntt-20.ecl.net
  2365.  
  2366. Mitsuru Maruyama
  2367. NTT Software Laboratories
  2368. 3-9-11, Midori-cho
  2369. Musashino-shi
  2370. Tokyo 180, Japan
  2371. E-mail: mitsuru@ntt-20.ecl.net
  2372.  
  2373.  
  2374.  
  2375.  
  2376.  
  2377. Murakami & Maruyama Informational [Page 6]
  2379.  
  2380.  
  2381.  
  2382.  
  2383.  
  2384.  
  2385.  
  2386. Network Working Group K. Murakami
  2387. Request for Comments: 2173 M. Maruyama
  2388. Category: Informational NTT Laboratories
  2389. June 1997
  2390.  
  2391.  
  2392. A MAPOS version 1 Extension - Node Switch Protocol
  2393.  
  2394. Status of this Memo
  2395.  
  2396. This memo provides information for the Internet community. This memo
  2397. does not specify an Internet standard of any kind. Distribution of
  2398. this memo is unlimited.
  2399.  
  2400. Abstract
  2401.  
  2402. This document describes a MAPOS extension, Node Switch Protocol, for
  2403. automatic node address assignment. MAPOS is a multiple access
  2404. protocol for transmission of network-protocol datagrams, encapsulated
  2405. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  2406. automates the HDLC address configuration of each node. Using NSP, a
  2407. node retrieves its HDLC address from the switch to which it is
  2408. connected.
  2409.  
  2410. 1. Introduction
  2411.  
  2412. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  2413. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  2414. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  2415. switch provides multiple access capability to each node. In MAPOS,
  2416. each node has a unique HDLC address within a switch. The address is
  2417. equivalent to the port number of the switch to which the node is
  2418. connected. This document describes an extension to MAPOS, Node
  2419. Switch Protocol, which enable automatic HDLC address assignment.
  2420. First, it explains the addressing of MAPOS. Then, it describes the
  2421. NSP protocol for automatic HDLC node address assignment.
  2422.  
  2423. 2. Node Address Format
  2424.  
  2425. This section describes MAPOS Version 1 address format in single and
  2426. multiple switch environment.
  2427.  
  2428.  
  2429.  
  2430.  
  2431.  
  2432.  
  2433.  
  2434.  
  2435.  
  2436.  
  2437. Murakami & Maruyama Informational [Page 1]
  2439. RFC 2173 MAPOS June 1997
  2440.  
  2441.  
  2442. 2.1 Address Format
  2443.  
  2444. In MAPOS network, each end node has a unique HDLC address. As shown
  2445. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  2446. indicates the end of the field. When a SONET switch receives an HDLC
  2447. frame, it forwards the frame based on the address in the frame
  2448. header.
  2449.  
  2450. In unicast, MSB is 0 and the rest of the bits are the port number to
  2451. which a node is connected. Since the LSB is always 1, the minimum and
  2452. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  2453. reserved and is assigned to the control processor in a SONET switch.
  2454.  
  2455. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  2456. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  2457. indicate the group address.
  2458.  
  2459. +-------------+-+
  2460. | | | | | | | | |
  2461. | |port number|1|
  2462. +-+-----------+-+
  2463. ^ ^
  2464. | |
  2465. | +------- EA bit (always 1)
  2466. |
  2467. 1 : broadcast, multicast
  2468. 0 : unicast
  2469.  
  2470. Figure 1 Address format
  2471.  
  2472. 2.2 Address in multi-switch environment
  2473.  
  2474. In a multi-switch environment, variable-length subnet addressing is
  2475. used. Each switch has a switch number that is unique within the
  2476. system. Subnetted node addresses consist of the switch number and the
  2477. port number to which a node is connected. The address format is "0
  2478. <switch number> <node number> 1" for a unicast address, "all 1" for
  2479. the broadcast address, and "1 <group address> 1" for a multicast
  2480. address.
  2481.  
  2482. The address 0x01 is reserved and is assigned to the control processor
  2483. in the "local" switch. That is, it indicates the switch itself to
  2484. which the node is connected. The addresses of the form "0 <switch
  2485. number> <all 0> 1" are reserved, and indicates the control processor
  2486. of the switch designated by the switch number.
  2487.  
  2488. In Figure 2, the switch numbers are two bits long. Node N1 is
  2489. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  2490.  
  2491.  
  2492.  
  2493. Murakami & Maruyama Informational [Page 2]
  2495. RFC 2173 MAPOS June 1997
  2496.  
  2497.  
  2498. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  2499. has an address 01001001(0x49), since the switch number of S2 is 0x2
  2500. (10 in binary) and the port number is 0x09. Note that all the port
  2501. numbers are odd because the LSBs are always 1.
  2502.  
  2503. +------+
  2504. | node |
  2505. | N1 |
  2506. +------+
  2507. | 00100011(0x23)
  2508. |
  2509. |0x3 |0x3
  2510. +------+ +---+----+ +---+----+ +------+
  2511. | node +----+ SONET +-------+ SONET +-----+ node |
  2512. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  2513. +------+ | S1 | | S2 | +------+
  2514. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  2515. +---+----+ +---+----+
  2516. |0x7 |0x7
  2517.  
  2518.  
  2519. Figure 2 Addressing in Multiple Switch Environment
  2520.  
  2521. 4 NSP(Node-Switch Protocol)
  2522.  
  2523. This section describes the NSP protocol used for automatic node
  2524. address assignment.
  2525.  
  2526. 4.1 NSP protocol
  2527.  
  2528. NSP is introduced to provide an automatic node address assignment
  2529. function in MAPOS version 1. It reduces the administrative overhead
  2530. of node address configuration for each node and prevents troubles
  2531. such as address inconsistency and collision. When a node is connected
  2532. to a switch and receives SONET signal correctly, the node sends an
  2533. address request packet to the control processor in the local switch.
  2534. The destination address of this packet is 00000001(0x01). When the
  2535. control processor receives the packet, it replies with an address
  2536. assignment packet. The destination is the assigned node address. If
  2537. the node does not receive the address assignment packet within 5
  2538. seconds, it retransmits the address request packet. The
  2539. retransmission continues until the node successfully receives the
  2540. address assignment packet.
  2541.  
  2542. Whenever a node detects a transmission error such as carrier loss or
  2543. out-of-synchronization, it SHOULD send an address request packet to
  2544. the control processor and verify its current address. In addition, a
  2545. node MUST verify its address by sending address request packets every
  2546.  
  2547.  
  2548.  
  2549. Murakami & Maruyama Informational [Page 3]
  2551. RFC 2173 MAPOS June 1997
  2552.  
  2553.  
  2554. 30 seconds. The switch regards them as keep-alive packets and
  2555. utilizes them to detect the node's status. If it has not received a
  2556. request packet for more than 90 seconds, it assumes that the node
  2557. went down. In addition, it also assumes the node went down when a
  2558. switch detects a SONET signal failure.
  2559.  
  2560. 4.2 Packet Format
  2561.  
  2562. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  2563. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  2564. information field contains the NSP packet as shown in Figure 3.
  2565.  
  2566.  
  2567. +-----------+------------+
  2568. I command I address I
  2569. +-----------+------------+
  2570. I<- 32bit ->I<- 32 bit ->I
  2571.  
  2572. Figure 3 NSP packet format
  2573.  
  2574. The command field is 32 bits long and has the following values (in
  2575. decimal);
  2576.  
  2577. 1 address request
  2578. 2 address assignment
  2579. 3 reject(error)
  2580.  
  2581. The length of the address field is 32bits. In address request
  2582. packets, the NSP address field SHOULD be filled with zeroes, although
  2583. the switch ignores it. In address assignment packets, the assigned
  2584. address is placed in the least significant byte of the field. The
  2585. rest of the field is padded with zeroes. When the switch can not
  2586. assign the address for some reason, the switch replies with a reject
  2587. command (the values is 3). The value of the address field is
  2588. undefined.
  2589.  
  2590. 4.3 Consideration for special cases
  2591.  
  2592. There are two special cases to consider. One is a point-to-point
  2593. connection without a switch. The other is loop-back, that is, direct
  2594. connection between the input and the output of the same port.
  2595.  
  2596. 4.3.1 point-to-point
  2597.  
  2598. In the case of a point-to-point connection shown in Figure 4, a node
  2599. sends an address request packet to the other node. The destination
  2600. address is 00000001(0x01), that is usually a control processor in a
  2601. switch. When a node receives the address request, it detects the
  2602.  
  2603.  
  2604.  
  2605. Murakami & Maruyama Informational [Page 4]
  2607. RFC 2173 MAPOS June 1997
  2608.  
  2609.  
  2610. point-to-point connection by examining both the destination address
  2611. and the command contained. Then, it MUST reply with an address
  2612. assignment packet. The assigned address MUST be 00000011(0x03). Since
  2613. both nodes send an address request to each other, both of them get
  2614. address 00000011(0x03). Since any address can be used in point-to-
  2615. point environment, there is no problem even if both of the nodes have
  2616. the same address.
  2617.  
  2618. ---- address request ----> 0x01
  2619. 0x03 <---- address assignment ----
  2620. +------+ +------+
  2621. | node +--------------------------------+ node |
  2622. +------+ +------+
  2623. 0x01 <---- address request ----
  2624. ---- address assignment ----> 0x03
  2625.  
  2626. Figure 4 Point-to-point connection
  2627.  
  2628. 4.3.2 loop-back
  2629.  
  2630. Another special case is loop-back where the output port of a node is
  2631. simply connected to its input port as shown in Figure 5. In this
  2632. case, the same mechanism as that for point-to-point can be applied
  2633. without modification. A node sends an address request packet
  2634. destined to 00000001(0x01). The node then receives the same packet.
  2635. Since the destination is 00000001(0x01), it replies with an address
  2636. assignment packet, containing the assigned address 00000011(0x03), to
  2637. the address 0000 0011(0x03). Thus, the node obtains the address
  2638. 00000011(0x03).
  2639.  
  2640. ---- address request ----> 0x01
  2641. +------+ --- address assignment --> 0x03
  2642. | +-------------->-----------------+
  2643. | node + |
  2644. | +--------------<-----------------+
  2645. +------+
  2646.  
  2647. Figure 5 Loop-back Configuration
  2648.  
  2649.  
  2650.  
  2651.  
  2652.  
  2653.  
  2654.  
  2655.  
  2656.  
  2657.  
  2658.  
  2659.  
  2660.  
  2661. Murakami & Maruyama Informational [Page 5]
  2663. RFC 2173 MAPOS June 1997
  2664.  
  2665.  
  2666. 5. Security Considerations
  2667.  
  2668. Security issues are not discussed in this memo.
  2669.  
  2670. References
  2671.  
  2672. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  2673. over SONET/SDH, Version 1," RFC-2171, June 1997.
  2674.  
  2675. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  2676. Rates (1990).
  2677.  
  2678. [3] CCITT Recommendation G.708: Network Node Interface for
  2679. Synchronous Digital Hierarchy (1990).
  2680.  
  2681. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  2682. (1990).
  2683.  
  2684. [5] American National Standard for Telecommunications - Digital
  2685. Hierarchy - Optical Interface Rates and Formats Specification,
  2686. ANSI T1.105-1991.
  2687.  
  2688. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  2689. Numbers," RFC-2172, June, 1997.
  2690.  
  2691. Acknowledgements
  2692.  
  2693. The authors would like to acknowledge the contributions and
  2694. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  2695. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  2696.  
  2697. Authors' Address
  2698.  
  2699. Ken Murakami
  2700. NTT Software Laboratories
  2701. 3-9-11, Midori-cho
  2702. Musashino-shi
  2703. Tokyo 180, Japan
  2704. E-mail: murakami@ntt-20.ecl.net
  2705.  
  2706. Mitsuru Maruyama
  2707. NTT Software Laboratories
  2708. 3-9-11, Midori-cho
  2709. Musashino-shi
  2710. Tokyo 180, Japan
  2711. E-mail: mitsuru@ntt-20.ecl.net
  2712.  
  2713.  
  2714.  
  2715.  
  2716.  
  2717. Murakami & Maruyama Informational [Page 6]
  2719.  
  2720.  
  2721.  
  2722.  
  2723.  
  2724.  
  2725.  
  2726. Network Working Group K. Murakami
  2727. Request for Comments: 2173 M. Maruyama
  2728. Category: Informational NTT Laboratories
  2729. June 1997
  2730.  
  2731.  
  2732. A MAPOS version 1 Extension - Node Switch Protocol
  2733.  
  2734. Status of this Memo
  2735.  
  2736. This memo provides information for the Internet community. This memo
  2737. does not specify an Internet standard of any kind. Distribution of
  2738. this memo is unlimited.
  2739.  
  2740. Abstract
  2741.  
  2742. This document describes a MAPOS extension, Node Switch Protocol, for
  2743. automatic node address assignment. MAPOS is a multiple access
  2744. protocol for transmission of network-protocol datagrams, encapsulated
  2745. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  2746. automates the HDLC address configuration of each node. Using NSP, a
  2747. node retrieves its HDLC address from the switch to which it is
  2748. connected.
  2749.  
  2750. 1. Introduction
  2751.  
  2752. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  2753. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  2754. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  2755. switch provides multiple access capability to each node. In MAPOS,
  2756. each node has a unique HDLC address within a switch. The address is
  2757. equivalent to the port number of the switch to which the node is
  2758. connected. This document describes an extension to MAPOS, Node
  2759. Switch Protocol, which enable automatic HDLC address assignment.
  2760. First, it explains the addressing of MAPOS. Then, it describes the
  2761. NSP protocol for automatic HDLC node address assignment.
  2762.  
  2763. 2. Node Address Format
  2764.  
  2765. This section describes MAPOS Version 1 address format in single and
  2766. multiple switch environment.
  2767.  
  2768.  
  2769.  
  2770.  
  2771.  
  2772.  
  2773.  
  2774.  
  2775.  
  2776.  
  2777. Murakami & Maruyama Informational [Page 1]
  2779. RFC 2173 MAPOS June 1997
  2780.  
  2781.  
  2782. 2.1 Address Format
  2783.  
  2784. In MAPOS network, each end node has a unique HDLC address. As shown
  2785. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  2786. indicates the end of the field. When a SONET switch receives an HDLC
  2787. frame, it forwards the frame based on the address in the frame
  2788. header.
  2789.  
  2790. In unicast, MSB is 0 and the rest of the bits are the port number to
  2791. which a node is connected. Since the LSB is always 1, the minimum and
  2792. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  2793. reserved and is assigned to the control processor in a SONET switch.
  2794.  
  2795. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  2796. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  2797. indicate the group address.
  2798.  
  2799. +-------------+-+
  2800. | | | | | | | | |
  2801. | |port number|1|
  2802. +-+-----------+-+
  2803. ^ ^
  2804. | |
  2805. | +------- EA bit (always 1)
  2806. |
  2807. 1 : broadcast, multicast
  2808. 0 : unicast
  2809.  
  2810. Figure 1 Address format
  2811.  
  2812. 2.2 Address in multi-switch environment
  2813.  
  2814. In a multi-switch environment, variable-length subnet addressing is
  2815. used. Each switch has a switch number that is unique within the
  2816. system. Subnetted node addresses consist of the switch number and the
  2817. port number to which a node is connected. The address format is "0
  2818. <switch number> <node number> 1" for a unicast address, "all 1" for
  2819. the broadcast address, and "1 <group address> 1" for a multicast
  2820. address.
  2821.  
  2822. The address 0x01 is reserved and is assigned to the control processor
  2823. in the "local" switch. That is, it indicates the switch itself to
  2824. which the node is connected. The addresses of the form "0 <switch
  2825. number> <all 0> 1" are reserved, and indicates the control processor
  2826. of the switch designated by the switch number.
  2827.  
  2828. In Figure 2, the switch numbers are two bits long. Node N1 is
  2829. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  2830.  
  2831.  
  2832.  
  2833. Murakami & Maruyama Informational [Page 2]
  2835. RFC 2173 MAPOS June 1997
  2836.  
  2837.  
  2838. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  2839. has an address 01001001(0x49), since the switch number of S2 is 0x2
  2840. (10 in binary) and the port number is 0x09. Note that all the port
  2841. numbers are odd because the LSBs are always 1.
  2842.  
  2843. +------+
  2844. | node |
  2845. | N1 |
  2846. +------+
  2847. | 00100011(0x23)
  2848. |
  2849. |0x3 |0x3
  2850. +------+ +---+----+ +---+----+ +------+
  2851. | node +----+ SONET +-------+ SONET +-----+ node |
  2852. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  2853. +------+ | S1 | | S2 | +------+
  2854. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  2855. +---+----+ +---+----+
  2856. |0x7 |0x7
  2857.  
  2858.  
  2859. Figure 2 Addressing in Multiple Switch Environment
  2860.  
  2861. 4 NSP(Node-Switch Protocol)
  2862.  
  2863. This section describes the NSP protocol used for automatic node
  2864. address assignment.
  2865.  
  2866. 4.1 NSP protocol
  2867.  
  2868. NSP is introduced to provide an automatic node address assignment
  2869. function in MAPOS version 1. It reduces the administrative overhead
  2870. of node address configuration for each node and prevents troubles
  2871. such as address inconsistency and collision. When a node is connected
  2872. to a switch and receives SONET signal correctly, the node sends an
  2873. address request packet to the control processor in the local switch.
  2874. The destination address of this packet is 00000001(0x01). When the
  2875. control processor receives the packet, it replies with an address
  2876. assignment packet. The destination is the assigned node address. If
  2877. the node does not receive the address assignment packet within 5
  2878. seconds, it retransmits the address request packet. The
  2879. retransmission continues until the node successfully receives the
  2880. address assignment packet.
  2881.  
  2882. Whenever a node detects a transmission error such as carrier loss or
  2883. out-of-synchronization, it SHOULD send an address request packet to
  2884. the control processor and verify its current address. In addition, a
  2885. node MUST verify its address by sending address request packets every
  2886.  
  2887.  
  2888.  
  2889. Murakami & Maruyama Informational [Page 3]
  2891. RFC 2173 MAPOS June 1997
  2892.  
  2893.  
  2894. 30 seconds. The switch regards them as keep-alive packets and
  2895. utilizes them to detect the node's status. If it has not received a
  2896. request packet for more than 90 seconds, it assumes that the node
  2897. went down. In addition, it also assumes the node went down when a
  2898. switch detects a SONET signal failure.
  2899.  
  2900. 4.2 Packet Format
  2901.  
  2902. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  2903. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  2904. information field contains the NSP packet as shown in Figure 3.
  2905.  
  2906.  
  2907. +-----------+------------+
  2908. I command I address I
  2909. +-----------+------------+
  2910. I<- 32bit ->I<- 32 bit ->I
  2911.  
  2912. Figure 3 NSP packet format
  2913.  
  2914. The command field is 32 bits long and has the following values (in
  2915. decimal);
  2916.  
  2917. 1 address request
  2918. 2 address assignment
  2919. 3 reject(error)
  2920.  
  2921. The length of the address field is 32bits. In address request
  2922. packets, the NSP address field SHOULD be filled with zeroes, although
  2923. the switch ignores it. In address assignment packets, the assigned
  2924. address is placed in the least significant byte of the field. The
  2925. rest of the field is padded with zeroes. When the switch can not
  2926. assign the address for some reason, the switch replies with a reject
  2927. command (the values is 3). The value of the address field is
  2928. undefined.
  2929.  
  2930. 4.3 Consideration for special cases
  2931.  
  2932. There are two special cases to consider. One is a point-to-point
  2933. connection without a switch. The other is loop-back, that is, direct
  2934. connection between the input and the output of the same port.
  2935.  
  2936. 4.3.1 point-to-point
  2937.  
  2938. In the case of a point-to-point connection shown in Figure 4, a node
  2939. sends an address request packet to the other node. The destination
  2940. address is 00000001(0x01), that is usually a control processor in a
  2941. switch. When a node receives the address request, it detects the
  2942.  
  2943.  
  2944.  
  2945. Murakami & Maruyama Informational [Page 4]
  2947. RFC 2173 MAPOS June 1997
  2948.  
  2949.  
  2950. point-to-point connection by examining both the destination address
  2951. and the command contained. Then, it MUST reply with an address
  2952. assignment packet. The assigned address MUST be 00000011(0x03). Since
  2953. both nodes send an address request to each other, both of them get
  2954. address 00000011(0x03). Since any address can be used in point-to-
  2955. point environment, there is no problem even if both of the nodes have
  2956. the same address.
  2957.  
  2958. ---- address request ----> 0x01
  2959. 0x03 <---- address assignment ----
  2960. +------+ +------+
  2961. | node +--------------------------------+ node |
  2962. +------+ +------+
  2963. 0x01 <---- address request ----
  2964. ---- address assignment ----> 0x03
  2965.  
  2966. Figure 4 Point-to-point connection
  2967.  
  2968. 4.3.2 loop-back
  2969.  
  2970. Another special case is loop-back where the output port of a node is
  2971. simply connected to its input port as shown in Figure 5. In this
  2972. case, the same mechanism as that for point-to-point can be applied
  2973. without modification. A node sends an address request packet
  2974. destined to 00000001(0x01). The node then receives the same packet.
  2975. Since the destination is 00000001(0x01), it replies with an address
  2976. assignment packet, containing the assigned address 00000011(0x03), to
  2977. the address 0000 0011(0x03). Thus, the node obtains the address
  2978. 00000011(0x03).
  2979.  
  2980. ---- address request ----> 0x01
  2981. +------+ --- address assignment --> 0x03
  2982. | +-------------->-----------------+
  2983. | node + |
  2984. | +--------------<-----------------+
  2985. +------+
  2986.  
  2987. Figure 5 Loop-back Configuration
  2988.  
  2989.  
  2990.  
  2991.  
  2992.  
  2993.  
  2994.  
  2995.  
  2996.  
  2997.  
  2998.  
  2999.  
  3000.  
  3001. Murakami & Maruyama Informational [Page 5]
  3003. RFC 2173 MAPOS June 1997
  3004.  
  3005.  
  3006. 5. Security Considerations
  3007.  
  3008. Security issues are not discussed in this memo.
  3009.  
  3010. References
  3011.  
  3012. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  3013. over SONET/SDH, Version 1," RFC-2171, June 1997.
  3014.  
  3015. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  3016. Rates (1990).
  3017.  
  3018. [3] CCITT Recommendation G.708: Network Node Interface for
  3019. Synchronous Digital Hierarchy (1990).
  3020.  
  3021. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  3022. (1990).
  3023.  
  3024. [5] American National Standard for Telecommunications - Digital
  3025. Hierarchy - Optical Interface Rates and Formats Specification,
  3026. ANSI T1.105-1991.
  3027.  
  3028. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  3029. Numbers," RFC-2172, June, 1997.
  3030.  
  3031. Acknowledgements
  3032.  
  3033. The authors would like to acknowledge the contributions and
  3034. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  3035. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  3036.  
  3037. Authors' Address
  3038.  
  3039. Ken Murakami
  3040. NTT Software Laboratories
  3041. 3-9-11, Midori-cho
  3042. Musashino-shi
  3043. Tokyo 180, Japan
  3044. E-mail: murakami@ntt-20.ecl.net
  3045.  
  3046. Mitsuru Maruyama
  3047. NTT Software Laboratories
  3048. 3-9-11, Midori-cho
  3049. Musashino-shi
  3050. Tokyo 180, Japan
  3051. E-mail: mitsuru@ntt-20.ecl.net
  3052.  
  3053.  
  3054.  
  3055.  
  3056.  
  3057. Murakami & Maruyama Informational [Page 6]
  3059.  
  3060.  
  3061.  
  3062.  
  3063.  
  3064.  
  3065.  
  3066. Network Working Group K. Murakami
  3067. Request for Comments: 2173 M. Maruyama
  3068. Category: Informational NTT Laboratories
  3069. June 1997
  3070.  
  3071.  
  3072. A MAPOS version 1 Extension - Node Switch Protocol
  3073.  
  3074. Status of this Memo
  3075.  
  3076. This memo provides information for the Internet community. This memo
  3077. does not specify an Internet standard of any kind. Distribution of
  3078. this memo is unlimited.
  3079.  
  3080. Abstract
  3081.  
  3082. This document describes a MAPOS extension, Node Switch Protocol, for
  3083. automatic node address assignment. MAPOS is a multiple access
  3084. protocol for transmission of network-protocol datagrams, encapsulated
  3085. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  3086. automates the HDLC address configuration of each node. Using NSP, a
  3087. node retrieves its HDLC address from the switch to which it is
  3088. connected.
  3089.  
  3090. 1. Introduction
  3091.  
  3092. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  3093. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  3094. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  3095. switch provides multiple access capability to each node. In MAPOS,
  3096. each node has a unique HDLC address within a switch. The address is
  3097. equivalent to the port number of the switch to which the node is
  3098. connected. This document describes an extension to MAPOS, Node
  3099. Switch Protocol, which enable automatic HDLC address assignment.
  3100. First, it explains the addressing of MAPOS. Then, it describes the
  3101. NSP protocol for automatic HDLC node address assignment.
  3102.  
  3103. 2. Node Address Format
  3104.  
  3105. This section describes MAPOS Version 1 address format in single and
  3106. multiple switch environment.
  3107.  
  3108.  
  3109.  
  3110.  
  3111.  
  3112.  
  3113.  
  3114.  
  3115.  
  3116.  
  3117. Murakami & Maruyama Informational [Page 1]
  3119. RFC 2173 MAPOS June 1997
  3120.  
  3121.  
  3122. 2.1 Address Format
  3123.  
  3124. In MAPOS network, each end node has a unique HDLC address. As shown
  3125. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  3126. indicates the end of the field. When a SONET switch receives an HDLC
  3127. frame, it forwards the frame based on the address in the frame
  3128. header.
  3129.  
  3130. In unicast, MSB is 0 and the rest of the bits are the port number to
  3131. which a node is connected. Since the LSB is always 1, the minimum and
  3132. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  3133. reserved and is assigned to the control processor in a SONET switch.
  3134.  
  3135. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  3136. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  3137. indicate the group address.
  3138.  
  3139. +-------------+-+
  3140. | | | | | | | | |
  3141. | |port number|1|
  3142. +-+-----------+-+
  3143. ^ ^
  3144. | |
  3145. | +------- EA bit (always 1)
  3146. |
  3147. 1 : broadcast, multicast
  3148. 0 : unicast
  3149.  
  3150. Figure 1 Address format
  3151.  
  3152. 2.2 Address in multi-switch environment
  3153.  
  3154. In a multi-switch environment, variable-length subnet addressing is
  3155. used. Each switch has a switch number that is unique within the
  3156. system. Subnetted node addresses consist of the switch number and the
  3157. port number to which a node is connected. The address format is "0
  3158. <switch number> <node number> 1" for a unicast address, "all 1" for
  3159. the broadcast address, and "1 <group address> 1" for a multicast
  3160. address.
  3161.  
  3162. The address 0x01 is reserved and is assigned to the control processor
  3163. in the "local" switch. That is, it indicates the switch itself to
  3164. which the node is connected. The addresses of the form "0 <switch
  3165. number> <all 0> 1" are reserved, and indicates the control processor
  3166. of the switch designated by the switch number.
  3167.  
  3168. In Figure 2, the switch numbers are two bits long. Node N1 is
  3169. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  3170.  
  3171.  
  3172.  
  3173. Murakami & Maruyama Informational [Page 2]
  3175. RFC 2173 MAPOS June 1997
  3176.  
  3177.  
  3178. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  3179. has an address 01001001(0x49), since the switch number of S2 is 0x2
  3180. (10 in binary) and the port number is 0x09. Note that all the port
  3181. numbers are odd because the LSBs are always 1.
  3182.  
  3183. +------+
  3184. | node |
  3185. | N1 |
  3186. +------+
  3187. | 00100011(0x23)
  3188. |
  3189. |0x3 |0x3
  3190. +------+ +---+----+ +---+----+ +------+
  3191. | node +----+ SONET +-------+ SONET +-----+ node |
  3192. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  3193. +------+ | S1 | | S2 | +------+
  3194. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  3195. +---+----+ +---+----+
  3196. |0x7 |0x7
  3197.  
  3198.  
  3199. Figure 2 Addressing in Multiple Switch Environment
  3200.  
  3201. 4 NSP(Node-Switch Protocol)
  3202.  
  3203. This section describes the NSP protocol used for automatic node
  3204. address assignment.
  3205.  
  3206. 4.1 NSP protocol
  3207.  
  3208. NSP is introduced to provide an automatic node address assignment
  3209. function in MAPOS version 1. It reduces the administrative overhead
  3210. of node address configuration for each node and prevents troubles
  3211. such as address inconsistency and collision. When a node is connected
  3212. to a switch and receives SONET signal correctly, the node sends an
  3213. address request packet to the control processor in the local switch.
  3214. The destination address of this packet is 00000001(0x01). When the
  3215. control processor receives the packet, it replies with an address
  3216. assignment packet. The destination is the assigned node address. If
  3217. the node does not receive the address assignment packet within 5
  3218. seconds, it retransmits the address request packet. The
  3219. retransmission continues until the node successfully receives the
  3220. address assignment packet.
  3221.  
  3222. Whenever a node detects a transmission error such as carrier loss or
  3223. out-of-synchronization, it SHOULD send an address request packet to
  3224. the control processor and verify its current address. In addition, a
  3225. node MUST verify its address by sending address request packets every
  3226.  
  3227.  
  3228.  
  3229. Murakami & Maruyama Informational [Page 3]
  3231. RFC 2173 MAPOS June 1997
  3232.  
  3233.  
  3234. 30 seconds. The switch regards them as keep-alive packets and
  3235. utilizes them to detect the node's status. If it has not received a
  3236. request packet for more than 90 seconds, it assumes that the node
  3237. went down. In addition, it also assumes the node went down when a
  3238. switch detects a SONET signal failure.
  3239.  
  3240. 4.2 Packet Format
  3241.  
  3242. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  3243. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  3244. information field contains the NSP packet as shown in Figure 3.
  3245.  
  3246.  
  3247. +-----------+------------+
  3248. I command I address I
  3249. +-----------+------------+
  3250. I<- 32bit ->I<- 32 bit ->I
  3251.  
  3252. Figure 3 NSP packet format
  3253.  
  3254. The command field is 32 bits long and has the following values (in
  3255. decimal);
  3256.  
  3257. 1 address request
  3258. 2 address assignment
  3259. 3 reject(error)
  3260.  
  3261. The length of the address field is 32bits. In address request
  3262. packets, the NSP address field SHOULD be filled with zeroes, although
  3263. the switch ignores it. In address assignment packets, the assigned
  3264. address is placed in the least significant byte of the field. The
  3265. rest of the field is padded with zeroes. When the switch can not
  3266. assign the address for some reason, the switch replies with a reject
  3267. command (the values is 3). The value of the address field is
  3268. undefined.
  3269.  
  3270. 4.3 Consideration for special cases
  3271.  
  3272. There are two special cases to consider. One is a point-to-point
  3273. connection without a switch. The other is loop-back, that is, direct
  3274. connection between the input and the output of the same port.
  3275.  
  3276. 4.3.1 point-to-point
  3277.  
  3278. In the case of a point-to-point connection shown in Figure 4, a node
  3279. sends an address request packet to the other node. The destination
  3280. address is 00000001(0x01), that is usually a control processor in a
  3281. switch. When a node receives the address request, it detects the
  3282.  
  3283.  
  3284.  
  3285. Murakami & Maruyama Informational [Page 4]
  3287. RFC 2173 MAPOS June 1997
  3288.  
  3289.  
  3290. point-to-point connection by examining both the destination address
  3291. and the command contained. Then, it MUST reply with an address
  3292. assignment packet. The assigned address MUST be 00000011(0x03). Since
  3293. both nodes send an address request to each other, both of them get
  3294. address 00000011(0x03). Since any address can be used in point-to-
  3295. point environment, there is no problem even if both of the nodes have
  3296. the same address.
  3297.  
  3298. ---- address request ----> 0x01
  3299. 0x03 <---- address assignment ----
  3300. +------+ +------+
  3301. | node +--------------------------------+ node |
  3302. +------+ +------+
  3303. 0x01 <---- address request ----
  3304. ---- address assignment ----> 0x03
  3305.  
  3306. Figure 4 Point-to-point connection
  3307.  
  3308. 4.3.2 loop-back
  3309.  
  3310. Another special case is loop-back where the output port of a node is
  3311. simply connected to its input port as shown in Figure 5. In this
  3312. case, the same mechanism as that for point-to-point can be applied
  3313. without modification. A node sends an address request packet
  3314. destined to 00000001(0x01). The node then receives the same packet.
  3315. Since the destination is 00000001(0x01), it replies with an address
  3316. assignment packet, containing the assigned address 00000011(0x03), to
  3317. the address 0000 0011(0x03). Thus, the node obtains the address
  3318. 00000011(0x03).
  3319.  
  3320. ---- address request ----> 0x01
  3321. +------+ --- address assignment --> 0x03
  3322. | +-------------->-----------------+
  3323. | node + |
  3324. | +--------------<-----------------+
  3325. +------+
  3326.  
  3327. Figure 5 Loop-back Configuration
  3328.  
  3329.  
  3330.  
  3331.  
  3332.  
  3333.  
  3334.  
  3335.  
  3336.  
  3337.  
  3338.  
  3339.  
  3340.  
  3341. Murakami & Maruyama Informational [Page 5]
  3343. RFC 2173 MAPOS June 1997
  3344.  
  3345.  
  3346. 5. Security Considerations
  3347.  
  3348. Security issues are not discussed in this memo.
  3349.  
  3350. References
  3351.  
  3352. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  3353. over SONET/SDH, Version 1," RFC-2171, June 1997.
  3354.  
  3355. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  3356. Rates (1990).
  3357.  
  3358. [3] CCITT Recommendation G.708: Network Node Interface for
  3359. Synchronous Digital Hierarchy (1990).
  3360.  
  3361. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  3362. (1990).
  3363.  
  3364. [5] American National Standard for Telecommunications - Digital
  3365. Hierarchy - Optical Interface Rates and Formats Specification,
  3366. ANSI T1.105-1991.
  3367.  
  3368. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  3369. Numbers," RFC-2172, June, 1997.
  3370.  
  3371. Acknowledgements
  3372.  
  3373. The authors would like to acknowledge the contributions and
  3374. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  3375. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  3376.  
  3377. Authors' Address
  3378.  
  3379. Ken Murakami
  3380. NTT Software Laboratories
  3381. 3-9-11, Midori-cho
  3382. Musashino-shi
  3383. Tokyo 180, Japan
  3384. E-mail: murakami@ntt-20.ecl.net
  3385.  
  3386. Mitsuru Maruyama
  3387. NTT Software Laboratories
  3388. 3-9-11, Midori-cho
  3389. Musashino-shi
  3390. Tokyo 180, Japan
  3391. E-mail: mitsuru@ntt-20.ecl.net
  3392.  
  3393.  
  3394.  
  3395.  
  3396.  
  3397. Murakami & Maruyama Informational [Page 6]
  3399.  
  3400.  
  3401.  
  3402.  
  3403.  
  3404.  
  3405.  
  3406.  
  3407.  
  3408. Network Working Group K. Murakami
  3409. Request for Comments: 2173 M. Maruyama
  3410. Category: Informational NTT Laboratories
  3411. June 1997
  3412.  
  3413.  
  3414. A MAPOS version 1 Extension - Node Switch Protocol
  3415.  
  3416. Status of this Memo
  3417.  
  3418. This memo provides information for the Internet community. This memo
  3419. does not specify an Internet standard of any kind. Distribution of
  3420. this memo is unlimited.
  3421.  
  3422. Abstract
  3423.  
  3424. This document describes a MAPOS extension, Node Switch Protocol, for
  3425. automatic node address assignment. MAPOS is a multiple access
  3426. protocol for transmission of network-protocol datagrams, encapsulated
  3427. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  3428. automates the HDLC address configuration of each node. Using NSP, a
  3429. node retrieves its HDLC address from the switch to which it is
  3430. connected.
  3431.  
  3432. 1. Introduction
  3433.  
  3434. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  3435. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  3436. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  3437. switch provides multiple access capability to each node. In MAPOS,
  3438. each node has a unique HDLC address within a switch. The address is
  3439. equivalent to the port number of the switch to which the node is
  3440. connected. This document describes an extension to MAPOS, Node
  3441. Switch Protocol, which enable automatic HDLC address assignment.
  3442. First, it explains the addressing of MAPOS. Then, it describes the
  3443. NSP protocol for automatic HDLC node address assignment.
  3444.  
  3445. 2. Node Address Format
  3446.  
  3447. This section describes MAPOS Version 1 address format in single and
  3448. multiple switch environment.
  3449.  
  3450.  
  3451.  
  3452.  
  3453.  
  3454.  
  3455.  
  3456.  
  3457.  
  3458.  
  3459. Murakami & Maruyama Informational [Page 1]
  3461. RFC 2173 MAPOS June 1997
  3462.  
  3463.  
  3464. 2.1 Address Format
  3465.  
  3466. In MAPOS network, each end node has a unique HDLC address. As shown
  3467. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  3468. indicates the end of the field. When a SONET switch receives an HDLC
  3469. frame, it forwards the frame based on the address in the frame
  3470. header.
  3471.  
  3472. In unicast, MSB is 0 and the rest of the bits are the port number to
  3473. which a node is connected. Since the LSB is always 1, the minimum and
  3474. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  3475. reserved and is assigned to the control processor in a SONET switch.
  3476.  
  3477. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  3478. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  3479. indicate the group address.
  3480.  
  3481. +-------------+-+
  3482. | | | | | | | | |
  3483. | |port number|1|
  3484. +-+-----------+-+
  3485. ^ ^
  3486. | |
  3487. | +------- EA bit (always 1)
  3488. |
  3489. 1 : broadcast, multicast
  3490. 0 : unicast
  3491.  
  3492. Figure 1 Address format
  3493.  
  3494. 2.2 Address in multi-switch environment
  3495.  
  3496. In a multi-switch environment, variable-length subnet addressing is
  3497. used. Each switch has a switch number that is unique within the
  3498. system. Subnetted node addresses consist of the switch number and the
  3499. port number to which a node is connected. The address format is "0
  3500. <switch number> <node number> 1" for a unicast address, "all 1" for
  3501. the broadcast address, and "1 <group address> 1" for a multicast
  3502. address.
  3503.  
  3504. The address 0x01 is reserved and is assigned to the control processor
  3505. in the "local" switch. That is, it indicates the switch itself to
  3506. which the node is connected. The addresses of the form "0 <switch
  3507. number> <all 0> 1" are reserved, and indicates the control processor
  3508. of the switch designated by the switch number.
  3509.  
  3510. In Figure 2, the switch numbers are two bits long. Node N1 is
  3511. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  3512.  
  3513.  
  3514.  
  3515. Murakami & Maruyama Informational [Page 2]
  3517. RFC 2173 MAPOS June 1997
  3518.  
  3519.  
  3520. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  3521. has an address 01001001(0x49), since the switch number of S2 is 0x2
  3522. (10 in binary) and the port number is 0x09. Note that all the port
  3523. numbers are odd because the LSBs are always 1.
  3524.  
  3525. +------+
  3526. | node |
  3527. | N1 |
  3528. +------+
  3529. | 00100011(0x23)
  3530. |
  3531. |0x3 |0x3
  3532. +------+ +---+----+ +---+----+ +------+
  3533. | node +----+ SONET +-------+ SONET +-----+ node |
  3534. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  3535. +------+ | S1 | | S2 | +------+
  3536. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  3537. +---+----+ +---+----+
  3538. |0x7 |0x7
  3539.  
  3540.  
  3541. Figure 2 Addressing in Multiple Switch Environment
  3542.  
  3543. 4 NSP(Node-Switch Protocol)
  3544.  
  3545. This section describes the NSP protocol used for automatic node
  3546. address assignment.
  3547.  
  3548. 4.1 NSP protocol
  3549.  
  3550. NSP is introduced to provide an automatic node address assignment
  3551. function in MAPOS version 1. It reduces the administrative overhead
  3552. of node address configuration for each node and prevents troubles
  3553. such as address inconsistency and collision. When a node is connected
  3554. to a switch and receives SONET signal correctly, the node sends an
  3555. address request packet to the control processor in the local switch.
  3556. The destination address of this packet is 00000001(0x01). When the
  3557. control processor receives the packet, it replies with an address
  3558. assignment packet. The destination is the assigned node address. If
  3559. the node does not receive the address assignment packet within 5
  3560. seconds, it retransmits the address request packet. The
  3561. retransmission continues until the node successfully receives the
  3562. address assignment packet.
  3563.  
  3564. Whenever a node detects a transmission error such as carrier loss or
  3565. out-of-synchronization, it SHOULD send an address request packet to
  3566. the control processor and verify its current address. In addition, a
  3567. node MUST verify its address by sending address request packets every
  3568.  
  3569.  
  3570.  
  3571. Murakami & Maruyama Informational [Page 3]
  3573. RFC 2173 MAPOS June 1997
  3574.  
  3575.  
  3576. 30 seconds. The switch regards them as keep-alive packets and
  3577. utilizes them to detect the node's status. If it has not received a
  3578. request packet for more than 90 seconds, it assumes that the node
  3579. went down. In addition, it also assumes the node went down when a
  3580. switch detects a SONET signal failure.
  3581.  
  3582. 4.2 Packet Format
  3583.  
  3584. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  3585. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  3586. information field contains the NSP packet as shown in Figure 3.
  3587.  
  3588.  
  3589. +-----------+------------+
  3590. I command I address I
  3591. +-----------+------------+
  3592. I<- 32bit ->I<- 32 bit ->I
  3593.  
  3594. Figure 3 NSP packet format
  3595.  
  3596. The command field is 32 bits long and has the following values (in
  3597. decimal);
  3598.  
  3599. 1 address request
  3600. 2 address assignment
  3601. 3 reject(error)
  3602.  
  3603. The length of the address field is 32bits. In address request
  3604. packets, the NSP address field SHOULD be filled with zeroes, although
  3605. the switch ignores it. In address assignment packets, the assigned
  3606. address is placed in the least significant byte of the field. The
  3607. rest of the field is padded with zeroes. When the switch can not
  3608. assign the address for some reason, the switch replies with a reject
  3609. command (the values is 3). The value of the address field is
  3610. undefined.
  3611.  
  3612. 4.3 Consideration for special cases
  3613.  
  3614. There are two special cases to consider. One is a point-to-point
  3615. connection without a switch. The other is loop-back, that is, direct
  3616. connection between the input and the output of the same port.
  3617.  
  3618. 4.3.1 point-to-point
  3619.  
  3620. In the case of a point-to-point connection shown in Figure 4, a node
  3621. sends an address request packet to the other node. The destination
  3622. address is 00000001(0x01), that is usually a control processor in a
  3623. switch. When a node receives the address request, it detects the
  3624.  
  3625.  
  3626.  
  3627. Murakami & Maruyama Informational [Page 4]
  3629. RFC 2173 MAPOS June 1997
  3630.  
  3631.  
  3632. point-to-point connection by examining both the destination address
  3633. and the command contained. Then, it MUST reply with an address
  3634. assignment packet. The assigned address MUST be 00000011(0x03). Since
  3635. both nodes send an address request to each other, both of them get
  3636. address 00000011(0x03). Since any address can be used in point-to-
  3637. point environment, there is no problem even if both of the nodes have
  3638. the same address.
  3639.  
  3640. ---- address request ----> 0x01
  3641. 0x03 <---- address assignment ----
  3642. +------+ +------+
  3643. | node +--------------------------------+ node |
  3644. +------+ +------+
  3645. 0x01 <---- address request ----
  3646. ---- address assignment ----> 0x03
  3647.  
  3648. Figure 4 Point-to-point connection
  3649.  
  3650. 4.3.2 loop-back
  3651.  
  3652. Another special case is loop-back where the output port of a node is
  3653. simply connected to its input port as shown in Figure 5. In this
  3654. case, the same mechanism as that for point-to-point can be applied
  3655. without modification. A node sends an address request packet
  3656. destined to 00000001(0x01). The node then receives the same packet.
  3657. Since the destination is 00000001(0x01), it replies with an address
  3658. assignment packet, containing the assigned address 00000011(0x03), to
  3659. the address 0000 0011(0x03). Thus, the node obtains the address
  3660. 00000011(0x03).
  3661.  
  3662. ---- address request ----> 0x01
  3663. +------+ --- address assignment --> 0x03
  3664. | +-------------->-----------------+
  3665. | node + |
  3666. | +--------------<-----------------+
  3667. +------+
  3668.  
  3669. Figure 5 Loop-back Configuration
  3670.  
  3671.  
  3672.  
  3673.  
  3674.  
  3675.  
  3676.  
  3677.  
  3678.  
  3679.  
  3680.  
  3681.  
  3682.  
  3683. Murakami & Maruyama Informational [Page 5]
  3685. RFC 2173 MAPOS June 1997
  3686.  
  3687.  
  3688. 5. Security Considerations
  3689.  
  3690. Security issues are not discussed in this memo.
  3691.  
  3692. References
  3693.  
  3694. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  3695. over SONET/SDH, Version 1," RFC-2171, June 1997.
  3696.  
  3697. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  3698. Rates (1990).
  3699.  
  3700. [3] CCITT Recommendation G.708: Network Node Interface for
  3701. Synchronous Digital Hierarchy (1990).
  3702.  
  3703. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  3704. (1990).
  3705.  
  3706. [5] American National Standard for Telecommunications - Digital
  3707. Hierarchy - Optical Interface Rates and Formats Specification,
  3708. ANSI T1.105-1991.
  3709.  
  3710. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  3711. Numbers," RFC-2172, June, 1997.
  3712.  
  3713. Acknowledgements
  3714.  
  3715. The authors would like to acknowledge the contributions and
  3716. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  3717. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  3718.  
  3719. Authors' Address
  3720.  
  3721. Ken Murakami
  3722. NTT Software Laboratories
  3723. 3-9-11, Midori-cho
  3724. Musashino-shi
  3725. Tokyo 180, Japan
  3726. E-mail: murakami@ntt-20.ecl.net
  3727.  
  3728. Mitsuru Maruyama
  3729. NTT Software Laboratories
  3730. 3-9-11, Midori-cho
  3731. Musashino-shi
  3732. Tokyo 180, Japan
  3733. E-mail: mitsuru@ntt-20.ecl.net
  3734.  
  3735.  
  3736.  
  3737.  
  3738.  
  3739. Murakami & Maruyama Informational [Page 6]
  3740.  
  3741.  
  3742.  
  3743.  
  3744.  
  3745.  
  3746.  
  3747. Network Working Group K. Murakami
  3748. Request for Comments: 2173 M. Maruyama
  3749. Category: Informational NTT Laboratories
  3750. June 1997
  3751.  
  3752.  
  3753. A MAPOS version 1 Extension - Node Switch Protocol
  3754.  
  3755. Status of this Memo
  3756.  
  3757. This memo provides information for the Internet community. This memo
  3758. does not specify an Internet standard of any kind. Distribution of
  3759. this memo is unlimited.
  3760.  
  3761. Abstract
  3762.  
  3763. This document describes a MAPOS extension, Node Switch Protocol, for
  3764. automatic node address assignment. MAPOS is a multiple access
  3765. protocol for transmission of network-protocol datagrams, encapsulated
  3766. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  3767. automates the HDLC address configuration of each node. Using NSP, a
  3768. node retrieves its HDLC address from the switch to which it is
  3769. connected.
  3770.  
  3771. 1. Introduction
  3772.  
  3773. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  3774. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  3775. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  3776. switch provides multiple access capability to each node. In MAPOS,
  3777. each node has a unique HDLC address within a switch. The address is
  3778. equivalent to the port number of the switch to which the node is
  3779. connected. This document describes an extension to MAPOS, Node
  3780. Switch Protocol, which enable automatic HDLC address assignment.
  3781. First, it explains the addressing of MAPOS. Then, it describes the
  3782. NSP protocol for automatic HDLC node address assignment.
  3783.  
  3784. 2. Node Address Format
  3785.  
  3786. This section describes MAPOS Version 1 address format in single and
  3787. multiple switch environment.
  3788.  
  3789.  
  3790.  
  3791.  
  3792.  
  3793.  
  3794.  
  3795.  
  3796.  
  3797.  
  3798. Murakami & Maruyama Informational [Page 1]
  3800. RFC 2173 MAPOS June 1997
  3801.  
  3802.  
  3803. 2.1 Address Format
  3804.  
  3805. In MAPOS network, each end node has a unique HDLC address. As shown
  3806. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  3807. indicates the end of the field. When a SONET switch receives an HDLC
  3808. frame, it forwards the frame based on the address in the frame
  3809. header.
  3810.  
  3811. In unicast, MSB is 0 and the rest of the bits are the port number to
  3812. which a node is connected. Since the LSB is always 1, the minimum and
  3813. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  3814. reserved and is assigned to the control processor in a SONET switch.
  3815.  
  3816. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  3817. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  3818. indicate the group address.
  3819.  
  3820. +-------------+-+
  3821. | | | | | | | | |
  3822. | |port number|1|
  3823. +-+-----------+-+
  3824. ^ ^
  3825. | |
  3826. | +------- EA bit (always 1)
  3827. |
  3828. 1 : broadcast, multicast
  3829. 0 : unicast
  3830.  
  3831. Figure 1 Address format
  3832.  
  3833. 2.2 Address in multi-switch environment
  3834.  
  3835. In a multi-switch environment, variable-length subnet addressing is
  3836. used. Each switch has a switch number that is unique within the
  3837. system. Subnetted node addresses consist of the switch number and the
  3838. port number to which a node is connected. The address format is "0
  3839. <switch number> <node number> 1" for a unicast address, "all 1" for
  3840. the broadcast address, and "1 <group address> 1" for a multicast
  3841. address.
  3842.  
  3843. The address 0x01 is reserved and is assigned to the control processor
  3844. in the "local" switch. That is, it indicates the switch itself to
  3845. which the node is connected. The addresses of the form "0 <switch
  3846. number> <all 0> 1" are reserved, and indicates the control processor
  3847. of the switch designated by the switch number.
  3848.  
  3849. In Figure 2, the switch numbers are two bits long. Node N1 is
  3850. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  3851.  
  3852.  
  3853.  
  3854. Murakami & Maruyama Informational [Page 2]
  3856. RFC 2173 MAPOS June 1997
  3857.  
  3858.  
  3859. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  3860. has an address 01001001(0x49), since the switch number of S2 is 0x2
  3861. (10 in binary) and the port number is 0x09. Note that all the port
  3862. numbers are odd because the LSBs are always 1.
  3863.  
  3864. +------+
  3865. | node |
  3866. | N1 |
  3867. +------+
  3868. | 00100011(0x23)
  3869. |
  3870. |0x3 |0x3
  3871. +------+ +---+----+ +---+----+ +------+
  3872. | node +----+ SONET +-------+ SONET +-----+ node |
  3873. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  3874. +------+ | S1 | | S2 | +------+
  3875. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  3876. +---+----+ +---+----+
  3877. |0x7 |0x7
  3878.  
  3879.  
  3880. Figure 2 Addressing in Multiple Switch Environment
  3881.  
  3882. 4 NSP(Node-Switch Protocol)
  3883.  
  3884. This section describes the NSP protocol used for automatic node
  3885. address assignment.
  3886.  
  3887. 4.1 NSP protocol
  3888.  
  3889. NSP is introduced to provide an automatic node address assignment
  3890. function in MAPOS version 1. It reduces the administrative overhead
  3891. of node address configuration for each node and prevents troubles
  3892. such as address inconsistency and collision. When a node is connected
  3893. to a switch and receives SONET signal correctly, the node sends an
  3894. address request packet to the control processor in the local switch.
  3895. The destination address of this packet is 00000001(0x01). When the
  3896. control processor receives the packet, it replies with an address
  3897. assignment packet. The destination is the assigned node address. If
  3898. the node does not receive the address assignment packet within 5
  3899. seconds, it retransmits the address request packet. The
  3900. retransmission continues until the node successfully receives the
  3901. address assignment packet.
  3902.  
  3903. Whenever a node detects a transmission error such as carrier loss or
  3904. out-of-synchronization, it SHOULD send an address request packet to
  3905. the control processor and verify its current address. In addition, a
  3906. node MUST verify its address by sending address request packets every
  3907.  
  3908.  
  3909.  
  3910. Murakami & Maruyama Informational [Page 3]
  3912. RFC 2173 MAPOS June 1997
  3913.  
  3914.  
  3915. 30 seconds. The switch regards them as keep-alive packets and
  3916. utilizes them to detect the node's status. If it has not received a
  3917. request packet for more than 90 seconds, it assumes that the node
  3918. went down. In addition, it also assumes the node went down when a
  3919. switch detects a SONET signal failure.
  3920.  
  3921. 4.2 Packet Format
  3922.  
  3923. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  3924. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  3925. information field contains the NSP packet as shown in Figure 3.
  3926.  
  3927.  
  3928. +-----------+------------+
  3929. I command I address I
  3930. +-----------+------------+
  3931. I<- 32bit ->I<- 32 bit ->I
  3932.  
  3933. Figure 3 NSP packet format
  3934.  
  3935. The command field is 32 bits long and has the following values (in
  3936. decimal);
  3937.  
  3938. 1 address request
  3939. 2 address assignment
  3940. 3 reject(error)
  3941.  
  3942. The length of the address field is 32bits. In address request
  3943. packets, the NSP address field SHOULD be filled with zeroes, although
  3944. the switch ignores it. In address assignment packets, the assigned
  3945. address is placed in the least significant byte of the field. The
  3946. rest of the field is padded with zeroes. When the switch can not
  3947. assign the address for some reason, the switch replies with a reject
  3948. command (the values is 3). The value of the address field is
  3949. undefined.
  3950.  
  3951. 4.3 Consideration for special cases
  3952.  
  3953. There are two special cases to consider. One is a point-to-point
  3954. connection without a switch. The other is loop-back, that is, direct
  3955. connection between the input and the output of the same port.
  3956.  
  3957. 4.3.1 point-to-point
  3958.  
  3959. In the case of a point-to-point connection shown in Figure 4, a node
  3960. sends an address request packet to the other node. The destination
  3961. address is 00000001(0x01), that is usually a control processor in a
  3962. switch. When a node receives the address request, it detects the
  3963.  
  3964.  
  3965.  
  3966. Murakami & Maruyama Informational [Page 4]
  3968. RFC 2173 MAPOS June 1997
  3969.  
  3970.  
  3971. point-to-point connection by examining both the destination address
  3972. and the command contained. Then, it MUST reply with an address
  3973. assignment packet. The assigned address MUST be 00000011(0x03). Since
  3974. both nodes send an address request to each other, both of them get
  3975. address 00000011(0x03). Since any address can be used in point-to-
  3976. point environment, there is no problem even if both of the nodes have
  3977. the same address.
  3978.  
  3979. ---- address request ----> 0x01
  3980. 0x03 <---- address assignment ----
  3981. +------+ +------+
  3982. | node +--------------------------------+ node |
  3983. +------+ +------+
  3984. 0x01 <---- address request ----
  3985. ---- address assignment ----> 0x03
  3986.  
  3987. Figure 4 Point-to-point connection
  3988.  
  3989. 4.3.2 loop-back
  3990.  
  3991. Another special case is loop-back where the output port of a node is
  3992. simply connected to its input port as shown in Figure 5. In this
  3993. case, the same mechanism as that for point-to-point can be applied
  3994. without modification. A node sends an address request packet
  3995. destined to 00000001(0x01). The node then receives the same packet.
  3996. Since the destination is 00000001(0x01), it replies with an address
  3997. assignment packet, containing the assigned address 00000011(0x03), to
  3998. the address 0000 0011(0x03). Thus, the node obtains the address
  3999. 00000011(0x03).
  4000.  
  4001. ---- address request ----> 0x01
  4002. +------+ --- address assignment --> 0x03
  4003. | +-------------->-----------------+
  4004. | node + |
  4005. | +--------------<-----------------+
  4006. +------+
  4007.  
  4008. Figure 5 Loop-back Configuration
  4009.  
  4010.  
  4011.  
  4012.  
  4013.  
  4014.  
  4015.  
  4016.  
  4017.  
  4018.  
  4019.  
  4020.  
  4021.  
  4022. Murakami & Maruyama Informational [Page 5]
  4024. RFC 2173 MAPOS June 1997
  4025.  
  4026.  
  4027. 5. Security Considerations
  4028.  
  4029. Security issues are not discussed in this memo.
  4030.  
  4031. References
  4032.  
  4033. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  4034. over SONET/SDH, Version 1," RFC-2171, June 1997.
  4035.  
  4036. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  4037. Rates (1990).
  4038.  
  4039. [3] CCITT Recommendation G.708: Network Node Interface for
  4040. Synchronous Digital Hierarchy (1990).
  4041.  
  4042. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  4043. (1990).
  4044.  
  4045. [5] American National Standard for Telecommunications - Digital
  4046. Hierarchy - Optical Interface Rates and Formats Specification,
  4047. ANSI T1.105-1991.
  4048.  
  4049. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  4050. Numbers," RFC-2172, June, 1997.
  4051.  
  4052. Acknowledgements
  4053.  
  4054. The authors would like to acknowledge the contributions and
  4055. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  4056. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  4057.  
  4058. Authors' Address
  4059.  
  4060. Ken Murakami
  4061. NTT Software Laboratories
  4062. 3-9-11, Midori-cho
  4063. Musashino-shi
  4064. Tokyo 180, Japan
  4065. E-mail: murakami@ntt-20.ecl.net
  4066.  
  4067. Mitsuru Maruyama
  4068. NTT Software Laboratories
  4069. 3-9-11, Midori-cho
  4070. Musashino-shi
  4071. Tokyo 180, Japan
  4072. E-mail: mitsuru@ntt-20.ecl.net
  4073.  
  4074.  
  4075.  
  4076.  
  4077.  
  4078. Murakami & Maruyama Informational [Page 6]
  4080.  
  4081.  
  4082.  
  4083.  
  4084.  
  4085.  
  4086.  
  4087. Network Working Group K. Murakami
  4088. Request for Comments: 2173 M. Maruyama
  4089. Category: Informational NTT Laboratories
  4090. June 1997
  4091.  
  4092.  
  4093. A MAPOS version 1 Extension - Node Switch Protocol
  4094.  
  4095. Status of this Memo
  4096.  
  4097. This memo provides information for the Internet community. This memo
  4098. does not specify an Internet standard of any kind. Distribution of
  4099. this memo is unlimited.
  4100.  
  4101. Abstract
  4102.  
  4103. This document describes a MAPOS extension, Node Switch Protocol, for
  4104. automatic node address assignment. MAPOS is a multiple access
  4105. protocol for transmission of network-protocol datagrams, encapsulated
  4106. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  4107. automates the HDLC address configuration of each node. Using NSP, a
  4108. node retrieves its HDLC address from the switch to which it is
  4109. connected.
  4110.  
  4111. 1. Introduction
  4112.  
  4113. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  4114. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  4115. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  4116. switch provides multiple access capability to each node. In MAPOS,
  4117. each node has a unique HDLC address within a switch. The address is
  4118. equivalent to the port number of the switch to which the node is
  4119. connected. This document describes an extension to MAPOS, Node
  4120. Switch Protocol, which enable automatic HDLC address assignment.
  4121. First, it explains the addressing of MAPOS. Then, it describes the
  4122. NSP protocol for automatic HDLC node address assignment.
  4123.  
  4124. 2. Node Address Format
  4125.  
  4126. This section describes MAPOS Version 1 address format in single and
  4127. multiple switch environment.
  4128.  
  4129.  
  4130.  
  4131.  
  4132.  
  4133.  
  4134.  
  4135.  
  4136.  
  4137.  
  4138. Murakami & Maruyama Informational [Page 1]
  4140. RFC 2173 MAPOS June 1997
  4141.  
  4142.  
  4143. 2.1 Address Format
  4144.  
  4145. In MAPOS network, each end node has a unique HDLC address. As shown
  4146. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  4147. indicates the end of the field. When a SONET switch receives an HDLC
  4148. frame, it forwards the frame based on the address in the frame
  4149. header.
  4150.  
  4151. In unicast, MSB is 0 and the rest of the bits are the port number to
  4152. which a node is connected. Since the LSB is always 1, the minimum and
  4153. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  4154. reserved and is assigned to the control processor in a SONET switch.
  4155.  
  4156. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  4157. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  4158. indicate the group address.
  4159.  
  4160. +-------------+-+
  4161. | | | | | | | | |
  4162. | |port number|1|
  4163. +-+-----------+-+
  4164. ^ ^
  4165. | |
  4166. | +------- EA bit (always 1)
  4167. |
  4168. 1 : broadcast, multicast
  4169. 0 : unicast
  4170.  
  4171. Figure 1 Address format
  4172.  
  4173. 2.2 Address in multi-switch environment
  4174.  
  4175. In a multi-switch environment, variable-length subnet addressing is
  4176. used. Each switch has a switch number that is unique within the
  4177. system. Subnetted node addresses consist of the switch number and the
  4178. port number to which a node is connected. The address format is "0
  4179. <switch number> <node number> 1" for a unicast address, "all 1" for
  4180. the broadcast address, and "1 <group address> 1" for a multicast
  4181. address.
  4182.  
  4183. The address 0x01 is reserved and is assigned to the control processor
  4184. in the "local" switch. That is, it indicates the switch itself to
  4185. which the node is connected. The addresses of the form "0 <switch
  4186. number> <all 0> 1" are reserved, and indicates the control processor
  4187. of the switch designated by the switch number.
  4188.  
  4189. In Figure 2, the switch numbers are two bits long. Node N1 is
  4190. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  4191.  
  4192.  
  4193.  
  4194. Murakami & Maruyama Informational [Page 2]
  4196. RFC 2173 MAPOS June 1997
  4197.  
  4198.  
  4199. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  4200. has an address 01001001(0x49), since the switch number of S2 is 0x2
  4201. (10 in binary) and the port number is 0x09. Note that all the port
  4202. numbers are odd because the LSBs are always 1.
  4203.  
  4204. +------+
  4205. | node |
  4206. | N1 |
  4207. +------+
  4208. | 00100011(0x23)
  4209. |
  4210. |0x3 |0x3
  4211. +------+ +---+----+ +---+----+ +------+
  4212. | node +----+ SONET +-------+ SONET +-----+ node |
  4213. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  4214. +------+ | S1 | | S2 | +------+
  4215. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  4216. +---+----+ +---+----+
  4217. |0x7 |0x7
  4218.  
  4219.  
  4220. Figure 2 Addressing in Multiple Switch Environment
  4221.  
  4222. 4 NSP(Node-Switch Protocol)
  4223.  
  4224. This section describes the NSP protocol used for automatic node
  4225. address assignment.
  4226.  
  4227. 4.1 NSP protocol
  4228.  
  4229. NSP is introduced to provide an automatic node address assignment
  4230. function in MAPOS version 1. It reduces the administrative overhead
  4231. of node address configuration for each node and prevents troubles
  4232. such as address inconsistency and collision. When a node is connected
  4233. to a switch and receives SONET signal correctly, the node sends an
  4234. address request packet to the control processor in the local switch.
  4235. The destination address of this packet is 00000001(0x01). When the
  4236. control processor receives the packet, it replies with an address
  4237. assignment packet. The destination is the assigned node address. If
  4238. the node does not receive the address assignment packet within 5
  4239. seconds, it retransmits the address request packet. The
  4240. retransmission continues until the node successfully receives the
  4241. address assignment packet.
  4242.  
  4243. Whenever a node detects a transmission error such as carrier loss or
  4244. out-of-synchronization, it SHOULD send an address request packet to
  4245. the control processor and verify its current address. In addition, a
  4246. node MUST verify its address by sending address request packets every
  4247.  
  4248.  
  4249.  
  4250. Murakami & Maruyama Informational [Page 3]
  4252. RFC 2173 MAPOS June 1997
  4253.  
  4254.  
  4255. 30 seconds. The switch regards them as keep-alive packets and
  4256. utilizes them to detect the node's status. If it has not received a
  4257. request packet for more than 90 seconds, it assumes that the node
  4258. went down. In addition, it also assumes the node went down when a
  4259. switch detects a SONET signal failure.
  4260.  
  4261. 4.2 Packet Format
  4262.  
  4263. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  4264. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  4265. information field contains the NSP packet as shown in Figure 3.
  4266.  
  4267.  
  4268. +-----------+------------+
  4269. I command I address I
  4270. +-----------+------------+
  4271. I<- 32bit ->I<- 32 bit ->I
  4272.  
  4273. Figure 3 NSP packet format
  4274.  
  4275. The command field is 32 bits long and has the following values (in
  4276. decimal);
  4277.  
  4278. 1 address request
  4279. 2 address assignment
  4280. 3 reject(error)
  4281.  
  4282. The length of the address field is 32bits. In address request
  4283. packets, the NSP address field SHOULD be filled with zeroes, although
  4284. the switch ignores it. In address assignment packets, the assigned
  4285. address is placed in the least significant byte of the field. The
  4286. rest of the field is padded with zeroes. When the switch can not
  4287. assign the address for some reason, the switch replies with a reject
  4288. command (the values is 3). The value of the address field is
  4289. undefined.
  4290.  
  4291. 4.3 Consideration for special cases
  4292.  
  4293. There are two special cases to consider. One is a point-to-point
  4294. connection without a switch. The other is loop-back, that is, direct
  4295. connection between the input and the output of the same port.
  4296.  
  4297. 4.3.1 point-to-point
  4298.  
  4299. In the case of a point-to-point connection shown in Figure 4, a node
  4300. sends an address request packet to the other node. The destination
  4301. address is 00000001(0x01), that is usually a control processor in a
  4302. switch. When a node receives the address request, it detects the
  4303.  
  4304.  
  4305.  
  4306. Murakami & Maruyama Informational [Page 4]
  4308. RFC 2173 MAPOS June 1997
  4309.  
  4310.  
  4311. point-to-point connection by examining both the destination address
  4312. and the command contained. Then, it MUST reply with an address
  4313. assignment packet. The assigned address MUST be 00000011(0x03). Since
  4314. both nodes send an address request to each other, both of them get
  4315. address 00000011(0x03). Since any address can be used in point-to-
  4316. point environment, there is no problem even if both of the nodes have
  4317. the same address.
  4318.  
  4319. ---- address request ----> 0x01
  4320. 0x03 <---- address assignment ----
  4321. +------+ +------+
  4322. | node +--------------------------------+ node |
  4323. +------+ +------+
  4324. 0x01 <---- address request ----
  4325. ---- address assignment ----> 0x03
  4326.  
  4327. Figure 4 Point-to-point connection
  4328.  
  4329. 4.3.2 loop-back
  4330.  
  4331. Another special case is loop-back where the output port of a node is
  4332. simply connected to its input port as shown in Figure 5. In this
  4333. case, the same mechanism as that for point-to-point can be applied
  4334. without modification. A node sends an address request packet
  4335. destined to 00000001(0x01). The node then receives the same packet.
  4336. Since the destination is 00000001(0x01), it replies with an address
  4337. assignment packet, containing the assigned address 00000011(0x03), to
  4338. the address 0000 0011(0x03). Thus, the node obtains the address
  4339. 00000011(0x03).
  4340.  
  4341. ---- address request ----> 0x01
  4342. +------+ --- address assignment --> 0x03
  4343. | +-------------->-----------------+
  4344. | node + |
  4345. | +--------------<-----------------+
  4346. +------+
  4347.  
  4348. Figure 5 Loop-back Configuration
  4349.  
  4350.  
  4351.  
  4352.  
  4353.  
  4354.  
  4355.  
  4356.  
  4357.  
  4358.  
  4359.  
  4360.  
  4361.  
  4362. Murakami & Maruyama Informational [Page 5]
  4364. RFC 2173 MAPOS June 1997
  4365.  
  4366.  
  4367. 5. Security Considerations
  4368.  
  4369. Security issues are not discussed in this memo.
  4370.  
  4371. References
  4372.  
  4373. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  4374. over SONET/SDH, Version 1," RFC-2171, June 1997.
  4375.  
  4376. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  4377. Rates (1990).
  4378.  
  4379. [3] CCITT Recommendation G.708: Network Node Interface for
  4380. Synchronous Digital Hierarchy (1990).
  4381.  
  4382. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  4383. (1990).
  4384.  
  4385. [5] American National Standard for Telecommunications - Digital
  4386. Hierarchy - Optical Interface Rates and Formats Specification,
  4387. ANSI T1.105-1991.
  4388.  
  4389. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  4390. Numbers," RFC-2172, June, 1997.
  4391.  
  4392. Acknowledgements
  4393.  
  4394. The authors would like to acknowledge the contributions and
  4395. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  4396. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  4397.  
  4398. Authors' Address
  4399.  
  4400. Ken Murakami
  4401. NTT Software Laboratories
  4402. 3-9-11, Midori-cho
  4403. Musashino-shi
  4404. Tokyo 180, Japan
  4405. E-mail: murakami@ntt-20.ecl.net
  4406.  
  4407. Mitsuru Maruyama
  4408. NTT Software Laboratories
  4409. 3-9-11, Midori-cho
  4410. Musashino-shi
  4411. Tokyo 180, Japan
  4412. E-mail: mitsuru@ntt-20.ecl.net
  4413.  
  4414.  
  4415.  
  4416.  
  4417.  
  4418. Murakami & Maruyama Informational [Page 6]
  4420.  
  4421.  
  4422.  
  4423.  
  4424.  
  4425.  
  4426.  
  4427. Network Working Group K. Murakami
  4428. Request for Comments: 2173 M. Maruyama
  4429. Category: Informational NTT Laboratories
  4430. June 1997
  4431.  
  4432.  
  4433. A MAPOS version 1 Extension - Node Switch Protocol
  4434.  
  4435. Status of this Memo
  4436.  
  4437. This memo provides information for the Internet community. This memo
  4438. does not specify an Internet standard of any kind. Distribution of
  4439. this memo is unlimited.
  4440.  
  4441. Abstract
  4442.  
  4443. This document describes a MAPOS extension, Node Switch Protocol, for
  4444. automatic node address assignment. MAPOS is a multiple access
  4445. protocol for transmission of network-protocol datagrams, encapsulated
  4446. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  4447. automates the HDLC address configuration of each node. Using NSP, a
  4448. node retrieves its HDLC address from the switch to which it is
  4449. connected.
  4450.  
  4451. 1. Introduction
  4452.  
  4453. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  4454. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  4455. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  4456. switch provides multiple access capability to each node. In MAPOS,
  4457. each node has a unique HDLC address within a switch. The address is
  4458. equivalent to the port number of the switch to which the node is
  4459. connected. This document describes an extension to MAPOS, Node
  4460. Switch Protocol, which enable automatic HDLC address assignment.
  4461. First, it explains the addressing of MAPOS. Then, it describes the
  4462. NSP protocol for automatic HDLC node address assignment.
  4463.  
  4464. 2. Node Address Format
  4465.  
  4466. This section describes MAPOS Version 1 address format in single and
  4467. multiple switch environment.
  4468.  
  4469.  
  4470.  
  4471.  
  4472.  
  4473.  
  4474.  
  4475.  
  4476.  
  4477.  
  4478. Murakami & Maruyama Informational [Page 1]
  4480. RFC 2173 MAPOS June 1997
  4481.  
  4482.  
  4483. 2.1 Address Format
  4484.  
  4485. In MAPOS network, each end node has a unique HDLC address. As shown
  4486. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  4487. indicates the end of the field. When a SONET switch receives an HDLC
  4488. frame, it forwards the frame based on the address in the frame
  4489. header.
  4490.  
  4491. In unicast, MSB is 0 and the rest of the bits are the port number to
  4492. which a node is connected. Since the LSB is always 1, the minimum and
  4493. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  4494. reserved and is assigned to the control processor in a SONET switch.
  4495.  
  4496. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  4497. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  4498. indicate the group address.
  4499.  
  4500. +-------------+-+
  4501. | | | | | | | | |
  4502. | |port number|1|
  4503. +-+-----------+-+
  4504. ^ ^
  4505. | |
  4506. | +------- EA bit (always 1)
  4507. |
  4508. 1 : broadcast, multicast
  4509. 0 : unicast
  4510.  
  4511. Figure 1 Address format
  4512.  
  4513. 2.2 Address in multi-switch environment
  4514.  
  4515. In a multi-switch environment, variable-length subnet addressing is
  4516. used. Each switch has a switch number that is unique within the
  4517. system. Subnetted node addresses consist of the switch number and the
  4518. port number to which a node is connected. The address format is "0
  4519. <switch number> <node number> 1" for a unicast address, "all 1" for
  4520. the broadcast address, and "1 <group address> 1" for a multicast
  4521. address.
  4522.  
  4523. The address 0x01 is reserved and is assigned to the control processor
  4524. in the "local" switch. That is, it indicates the switch itself to
  4525. which the node is connected. The addresses of the form "0 <switch
  4526. number> <all 0> 1" are reserved, and indicates the control processor
  4527. of the switch designated by the switch number.
  4528.  
  4529. In Figure 2, the switch numbers are two bits long. Node N1 is
  4530. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  4531.  
  4532.  
  4533.  
  4534. Murakami & Maruyama Informational [Page 2]
  4536. RFC 2173 MAPOS June 1997
  4537.  
  4538.  
  4539. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  4540. has an address 01001001(0x49), since the switch number of S2 is 0x2
  4541. (10 in binary) and the port number is 0x09. Note that all the port
  4542. numbers are odd because the LSBs are always 1.
  4543.  
  4544. +------+
  4545. | node |
  4546. | N1 |
  4547. +------+
  4548. | 00100011(0x23)
  4549. |
  4550. |0x3 |0x3
  4551. +------+ +---+----+ +---+----+ +------+
  4552. | node +----+ SONET +-------+ SONET +-----+ node |
  4553. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  4554. +------+ | S1 | | S2 | +------+
  4555. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  4556. +---+----+ +---+----+
  4557. |0x7 |0x7
  4558.  
  4559.  
  4560. Figure 2 Addressing in Multiple Switch Environment
  4561.  
  4562. 4 NSP(Node-Switch Protocol)
  4563.  
  4564. This section describes the NSP protocol used for automatic node
  4565. address assignment.
  4566.  
  4567. 4.1 NSP protocol
  4568.  
  4569. NSP is introduced to provide an automatic node address assignment
  4570. function in MAPOS version 1. It reduces the administrative overhead
  4571. of node address configuration for each node and prevents troubles
  4572. such as address inconsistency and collision. When a node is connected
  4573. to a switch and receives SONET signal correctly, the node sends an
  4574. address request packet to the control processor in the local switch.
  4575. The destination address of this packet is 00000001(0x01). When the
  4576. control processor receives the packet, it replies with an address
  4577. assignment packet. The destination is the assigned node address. If
  4578. the node does not receive the address assignment packet within 5
  4579. seconds, it retransmits the address request packet. The
  4580. retransmission continues until the node successfully receives the
  4581. address assignment packet.
  4582.  
  4583. Whenever a node detects a transmission error such as carrier loss or
  4584. out-of-synchronization, it SHOULD send an address request packet to
  4585. the control processor and verify its current address. In addition, a
  4586. node MUST verify its address by sending address request packets every
  4587.  
  4588.  
  4589.  
  4590. Murakami & Maruyama Informational [Page 3]
  4592. RFC 2173 MAPOS June 1997
  4593.  
  4594.  
  4595. 30 seconds. The switch regards them as keep-alive packets and
  4596. utilizes them to detect the node's status. If it has not received a
  4597. request packet for more than 90 seconds, it assumes that the node
  4598. went down. In addition, it also assumes the node went down when a
  4599. switch detects a SONET signal failure.
  4600.  
  4601. 4.2 Packet Format
  4602.  
  4603. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  4604. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  4605. information field contains the NSP packet as shown in Figure 3.
  4606.  
  4607.  
  4608. +-----------+------------+
  4609. I command I address I
  4610. +-----------+------------+
  4611. I<- 32bit ->I<- 32 bit ->I
  4612.  
  4613. Figure 3 NSP packet format
  4614.  
  4615. The command field is 32 bits long and has the following values (in
  4616. decimal);
  4617.  
  4618. 1 address request
  4619. 2 address assignment
  4620. 3 reject(error)
  4621.  
  4622. The length of the address field is 32bits. In address request
  4623. packets, the NSP address field SHOULD be filled with zeroes, although
  4624. the switch ignores it. In address assignment packets, the assigned
  4625. address is placed in the least significant byte of the field. The
  4626. rest of the field is padded with zeroes. When the switch can not
  4627. assign the address for some reason, the switch replies with a reject
  4628. command (the values is 3). The value of the address field is
  4629. undefined.
  4630.  
  4631. 4.3 Consideration for special cases
  4632.  
  4633. There are two special cases to consider. One is a point-to-point
  4634. connection without a switch. The other is loop-back, that is, direct
  4635. connection between the input and the output of the same port.
  4636.  
  4637. 4.3.1 point-to-point
  4638.  
  4639. In the case of a point-to-point connection shown in Figure 4, a node
  4640. sends an address request packet to the other node. The destination
  4641. address is 00000001(0x01), that is usually a control processor in a
  4642. switch. When a node receives the address request, it detects the
  4643.  
  4644.  
  4645.  
  4646. Murakami & Maruyama Informational [Page 4]
  4648. RFC 2173 MAPOS June 1997
  4649.  
  4650.  
  4651. point-to-point connection by examining both the destination address
  4652. and the command contained. Then, it MUST reply with an address
  4653. assignment packet. The assigned address MUST be 00000011(0x03). Since
  4654. both nodes send an address request to each other, both of them get
  4655. address 00000011(0x03). Since any address can be used in point-to-
  4656. point environment, there is no problem even if both of the nodes have
  4657. the same address.
  4658.  
  4659. ---- address request ----> 0x01
  4660. 0x03 <---- address assignment ----
  4661. +------+ +------+
  4662. | node +--------------------------------+ node |
  4663. +------+ +------+
  4664. 0x01 <---- address request ----
  4665. ---- address assignment ----> 0x03
  4666.  
  4667. Figure 4 Point-to-point connection
  4668.  
  4669. 4.3.2 loop-back
  4670.  
  4671. Another special case is loop-back where the output port of a node is
  4672. simply connected to its input port as shown in Figure 5. In this
  4673. case, the same mechanism as that for point-to-point can be applied
  4674. without modification. A node sends an address request packet
  4675. destined to 00000001(0x01). The node then receives the same packet.
  4676. Since the destination is 00000001(0x01), it replies with an address
  4677. assignment packet, containing the assigned address 00000011(0x03), to
  4678. the address 0000 0011(0x03). Thus, the node obtains the address
  4679. 00000011(0x03).
  4680.  
  4681. ---- address request ----> 0x01
  4682. +------+ --- address assignment --> 0x03
  4683. | +-------------->-----------------+
  4684. | node + |
  4685. | +--------------<-----------------+
  4686. +------+
  4687.  
  4688. Figure 5 Loop-back Configuration
  4689.  
  4690.  
  4691.  
  4692.  
  4693.  
  4694.  
  4695.  
  4696.  
  4697.  
  4698.  
  4699.  
  4700.  
  4701.  
  4702. Murakami & Maruyama Informational [Page 5]
  4704. RFC 2173 MAPOS June 1997
  4705.  
  4706.  
  4707. 5. Security Considerations
  4708.  
  4709. Security issues are not discussed in this memo.
  4710.  
  4711. References
  4712.  
  4713. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  4714. over SONET/SDH, Version 1," RFC-2171, June 1997.
  4715.  
  4716. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  4717. Rates (1990).
  4718.  
  4719. [3] CCITT Recommendation G.708: Network Node Interface for
  4720. Synchronous Digital Hierarchy (1990).
  4721.  
  4722. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  4723. (1990).
  4724.  
  4725. [5] American National Standard for Telecommunications - Digital
  4726. Hierarchy - Optical Interface Rates and Formats Specification,
  4727. ANSI T1.105-1991.
  4728.  
  4729. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  4730. Numbers," RFC-2172, June, 1997.
  4731.  
  4732. Acknowledgements
  4733.  
  4734. The authors would like to acknowledge the contributions and
  4735. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  4736. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  4737.  
  4738. Authors' Address
  4739.  
  4740. Ken Murakami
  4741. NTT Software Laboratories
  4742. 3-9-11, Midori-cho
  4743. Musashino-shi
  4744. Tokyo 180, Japan
  4745. E-mail: murakami@ntt-20.ecl.net
  4746.  
  4747. Mitsuru Maruyama
  4748. NTT Software Laboratories
  4749. 3-9-11, Midori-cho
  4750. Musashino-shi
  4751. Tokyo 180, Japan
  4752. E-mail: mitsuru@ntt-20.ecl.net
  4753.  
  4754.  
  4755.  
  4756.  
  4757.  
  4758. Murakami & Maruyama Informational [Page 6]
  4760.  
  4761.  
  4762.  
  4763.  
  4764.  
  4765.  
  4766.  
  4767. Network Working Group K. Murakami
  4768. Request for Comments: 2173 M. Maruyama
  4769. Category: Informational NTT Laboratories
  4770. June 1997
  4771.  
  4772.  
  4773. A MAPOS version 1 Extension - Node Switch Protocol
  4774.  
  4775. Status of this Memo
  4776.  
  4777. This memo provides information for the Internet community. This memo
  4778. does not specify an Internet standard of any kind. Distribution of
  4779. this memo is unlimited.
  4780.  
  4781. Abstract
  4782.  
  4783. This document describes a MAPOS extension, Node Switch Protocol, for
  4784. automatic node address assignment. MAPOS is a multiple access
  4785. protocol for transmission of network-protocol datagrams, encapsulated
  4786. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  4787. automates the HDLC address configuration of each node. Using NSP, a
  4788. node retrieves its HDLC address from the switch to which it is
  4789. connected.
  4790.  
  4791. 1. Introduction
  4792.  
  4793. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  4794. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  4795. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  4796. switch provides multiple access capability to each node. In MAPOS,
  4797. each node has a unique HDLC address within a switch. The address is
  4798. equivalent to the port number of the switch to which the node is
  4799. connected. This document describes an extension to MAPOS, Node
  4800. Switch Protocol, which enable automatic HDLC address assignment.
  4801. First, it explains the addressing of MAPOS. Then, it describes the
  4802. NSP protocol for automatic HDLC node address assignment.
  4803.  
  4804. 2. Node Address Format
  4805.  
  4806. This section describes MAPOS Version 1 address format in single and
  4807. multiple switch environment.
  4808.  
  4809.  
  4810.  
  4811.  
  4812.  
  4813.  
  4814.  
  4815.  
  4816.  
  4817.  
  4818. Murakami & Maruyama Informational [Page 1]
  4820. RFC 2173 MAPOS June 1997
  4821.  
  4822.  
  4823. 2.1 Address Format
  4824.  
  4825. In MAPOS network, each end node has a unique HDLC address. As shown
  4826. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  4827. indicates the end of the field. When a SONET switch receives an HDLC
  4828. frame, it forwards the frame based on the address in the frame
  4829. header.
  4830.  
  4831. In unicast, MSB is 0 and the rest of the bits are the port number to
  4832. which a node is connected. Since the LSB is always 1, the minimum and
  4833. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  4834. reserved and is assigned to the control processor in a SONET switch.
  4835.  
  4836. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  4837. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  4838. indicate the group address.
  4839.  
  4840. +-------------+-+
  4841. | | | | | | | | |
  4842. | |port number|1|
  4843. +-+-----------+-+
  4844. ^ ^
  4845. | |
  4846. | +------- EA bit (always 1)
  4847. |
  4848. 1 : broadcast, multicast
  4849. 0 : unicast
  4850.  
  4851. Figure 1 Address format
  4852.  
  4853. 2.2 Address in multi-switch environment
  4854.  
  4855. In a multi-switch environment, variable-length subnet addressing is
  4856. used. Each switch has a switch number that is unique within the
  4857. system. Subnetted node addresses consist of the switch number and the
  4858. port number to which a node is connected. The address format is "0
  4859. <switch number> <node number> 1" for a unicast address, "all 1" for
  4860. the broadcast address, and "1 <group address> 1" for a multicast
  4861. address.
  4862.  
  4863. The address 0x01 is reserved and is assigned to the control processor
  4864. in the "local" switch. That is, it indicates the switch itself to
  4865. which the node is connected. The addresses of the form "0 <switch
  4866. number> <all 0> 1" are reserved, and indicates the control processor
  4867. of the switch designated by the switch number.
  4868.  
  4869. In Figure 2, the switch numbers are two bits long. Node N1 is
  4870. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  4871.  
  4872.  
  4873.  
  4874. Murakami & Maruyama Informational [Page 2]
  4876. RFC 2173 MAPOS June 1997
  4877.  
  4878.  
  4879. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  4880. has an address 01001001(0x49), since the switch number of S2 is 0x2
  4881. (10 in binary) and the port number is 0x09. Note that all the port
  4882. numbers are odd because the LSBs are always 1.
  4883.  
  4884. +------+
  4885. | node |
  4886. | N1 |
  4887. +------+
  4888. | 00100011(0x23)
  4889. |
  4890. |0x3 |0x3
  4891. +------+ +---+----+ +---+----+ +------+
  4892. | node +----+ SONET +-------+ SONET +-----+ node |
  4893. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  4894. +------+ | S1 | | S2 | +------+
  4895. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  4896. +---+----+ +---+----+
  4897. |0x7 |0x7
  4898.  
  4899.  
  4900. Figure 2 Addressing in Multiple Switch Environment
  4901.  
  4902. 4 NSP(Node-Switch Protocol)
  4903.  
  4904. This section describes the NSP protocol used for automatic node
  4905. address assignment.
  4906.  
  4907. 4.1 NSP protocol
  4908.  
  4909. NSP is introduced to provide an automatic node address assignment
  4910. function in MAPOS version 1. It reduces the administrative overhead
  4911. of node address configuration for each node and prevents troubles
  4912. such as address inconsistency and collision. When a node is connected
  4913. to a switch and receives SONET signal correctly, the node sends an
  4914. address request packet to the control processor in the local switch.
  4915. The destination address of this packet is 00000001(0x01). When the
  4916. control processor receives the packet, it replies with an address
  4917. assignment packet. The destination is the assigned node address. If
  4918. the node does not receive the address assignment packet within 5
  4919. seconds, it retransmits the address request packet. The
  4920. retransmission continues until the node successfully receives the
  4921. address assignment packet.
  4922.  
  4923. Whenever a node detects a transmission error such as carrier loss or
  4924. out-of-synchronization, it SHOULD send an address request packet to
  4925. the control processor and verify its current address. In addition, a
  4926. node MUST verify its address by sending address request packets every
  4927.  
  4928.  
  4929.  
  4930. Murakami & Maruyama Informational [Page 3]
  4932. RFC 2173 MAPOS June 1997
  4933.  
  4934.  
  4935. 30 seconds. The switch regards them as keep-alive packets and
  4936. utilizes them to detect the node's status. If it has not received a
  4937. request packet for more than 90 seconds, it assumes that the node
  4938. went down. In addition, it also assumes the node went down when a
  4939. switch detects a SONET signal failure.
  4940.  
  4941. 4.2 Packet Format
  4942.  
  4943. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  4944. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  4945. information field contains the NSP packet as shown in Figure 3.
  4946.  
  4947.  
  4948. +-----------+------------+
  4949. I command I address I
  4950. +-----------+------------+
  4951. I<- 32bit ->I<- 32 bit ->I
  4952.  
  4953. Figure 3 NSP packet format
  4954.  
  4955. The command field is 32 bits long and has the following values (in
  4956. decimal);
  4957.  
  4958. 1 address request
  4959. 2 address assignment
  4960. 3 reject(error)
  4961.  
  4962. The length of the address field is 32bits. In address request
  4963. packets, the NSP address field SHOULD be filled with zeroes, although
  4964. the switch ignores it. In address assignment packets, the assigned
  4965. address is placed in the least significant byte of the field. The
  4966. rest of the field is padded with zeroes. When the switch can not
  4967. assign the address for some reason, the switch replies with a reject
  4968. command (the values is 3). The value of the address field is
  4969. undefined.
  4970.  
  4971. 4.3 Consideration for special cases
  4972.  
  4973. There are two special cases to consider. One is a point-to-point
  4974. connection without a switch. The other is loop-back, that is, direct
  4975. connection between the input and the output of the same port.
  4976.  
  4977. 4.3.1 point-to-point
  4978.  
  4979. In the case of a point-to-point connection shown in Figure 4, a node
  4980. sends an address request packet to the other node. The destination
  4981. address is 00000001(0x01), that is usually a control processor in a
  4982. switch. When a node receives the address request, it detects the
  4983.  
  4984.  
  4985.  
  4986. Murakami & Maruyama Informational [Page 4]
  4988. RFC 2173 MAPOS June 1997
  4989.  
  4990.  
  4991. point-to-point connection by examining both the destination address
  4992. and the command contained. Then, it MUST reply with an address
  4993. assignment packet. The assigned address MUST be 00000011(0x03). Since
  4994. both nodes send an address request to each other, both of them get
  4995. address 00000011(0x03). Since any address can be used in point-to-
  4996. point environment, there is no problem even if both of the nodes have
  4997. the same address.
  4998.  
  4999. ---- address request ----> 0x01
  5000. 0x03 <---- address assignment ----
  5001. +------+ +------+
  5002. | node +--------------------------------+ node |
  5003. +------+ +------+
  5004. 0x01 <---- address request ----
  5005. ---- address assignment ----> 0x03
  5006.  
  5007. Figure 4 Point-to-point connection
  5008.  
  5009. 4.3.2 loop-back
  5010.  
  5011. Another special case is loop-back where the output port of a node is
  5012. simply connected to its input port as shown in Figure 5. In this
  5013. case, the same mechanism as that for point-to-point can be applied
  5014. without modification. A node sends an address request packet
  5015. destined to 00000001(0x01). The node then receives the same packet.
  5016. Since the destination is 00000001(0x01), it replies with an address
  5017. assignment packet, containing the assigned address 00000011(0x03), to
  5018. the address 0000 0011(0x03). Thus, the node obtains the address
  5019. 00000011(0x03).
  5020.  
  5021. ---- address request ----> 0x01
  5022. +------+ --- address assignment --> 0x03
  5023. | +-------------->-----------------+
  5024. | node + |
  5025. | +--------------<-----------------+
  5026. +------+
  5027.  
  5028. Figure 5 Loop-back Configuration
  5029.  
  5030.  
  5031.  
  5032.  
  5033.  
  5034.  
  5035.  
  5036.  
  5037.  
  5038.  
  5039.  
  5040.  
  5041.  
  5042. Murakami & Maruyama Informational [Page 5]
  5044. RFC 2173 MAPOS June 1997
  5045.  
  5046.  
  5047. 5. Security Considerations
  5048.  
  5049. Security issues are not discussed in this memo.
  5050.  
  5051. References
  5052.  
  5053. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  5054. over SONET/SDH, Version 1," RFC-2171, June 1997.
  5055.  
  5056. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  5057. Rates (1990).
  5058.  
  5059. [3] CCITT Recommendation G.708: Network Node Interface for
  5060. Synchronous Digital Hierarchy (1990).
  5061.  
  5062. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  5063. (1990).
  5064.  
  5065. [5] American National Standard for Telecommunications - Digital
  5066. Hierarchy - Optical Interface Rates and Formats Specification,
  5067. ANSI T1.105-1991.
  5068.  
  5069. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  5070. Numbers," RFC-2172, June, 1997.
  5071.  
  5072. Acknowledgements
  5073.  
  5074. The authors would like to acknowledge the contributions and
  5075. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  5076. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  5077.  
  5078. Authors' Address
  5079.  
  5080. Ken Murakami
  5081. NTT Software Laboratories
  5082. 3-9-11, Midori-cho
  5083. Musashino-shi
  5084. Tokyo 180, Japan
  5085. E-mail: murakami@ntt-20.ecl.net
  5086.  
  5087. Mitsuru Maruyama
  5088. NTT Software Laboratories
  5089. 3-9-11, Midori-cho
  5090. Musashino-shi
  5091. Tokyo 180, Japan
  5092. E-mail: mitsuru@ntt-20.ecl.net
  5093.  
  5094.  
  5095.  
  5096.  
  5097.  
  5098. Murakami & Maruyama Informational [Page 6]
  5100.  
  5101.  
  5102.  
  5103.  
  5104.  
  5105.  
  5106.  
  5107. Network Working Group K. Murakami
  5108. Request for Comments: 2173 M. Maruyama
  5109. Category: Informational NTT Laboratories
  5110. June 1997
  5111.  
  5112.  
  5113. A MAPOS version 1 Extension - Node Switch Protocol
  5114.  
  5115. Status of this Memo
  5116.  
  5117. This memo provides information for the Internet community. This memo
  5118. does not specify an Internet standard of any kind. Distribution of
  5119. this memo is unlimited.
  5120.  
  5121. Abstract
  5122.  
  5123. This document describes a MAPOS extension, Node Switch Protocol, for
  5124. automatic node address assignment. MAPOS is a multiple access
  5125. protocol for transmission of network-protocol datagrams, encapsulated
  5126. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  5127. automates the HDLC address configuration of each node. Using NSP, a
  5128. node retrieves its HDLC address from the switch to which it is
  5129. connected.
  5130.  
  5131. 1. Introduction
  5132.  
  5133. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  5134. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  5135. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  5136. switch provides multiple access capability to each node. In MAPOS,
  5137. each node has a unique HDLC address within a switch. The address is
  5138. equivalent to the port number of the switch to which the node is
  5139. connected. This document describes an extension to MAPOS, Node
  5140. Switch Protocol, which enable automatic HDLC address assignment.
  5141. First, it explains the addressing of MAPOS. Then, it describes the
  5142. NSP protocol for automatic HDLC node address assignment.
  5143.  
  5144. 2. Node Address Format
  5145.  
  5146. This section describes MAPOS Version 1 address format in single and
  5147. multiple switch environment.
  5148.  
  5149.  
  5150.  
  5151.  
  5152.  
  5153.  
  5154.  
  5155.  
  5156.  
  5157.  
  5158. Murakami & Maruyama Informational [Page 1]
  5160. RFC 2173 MAPOS June 1997
  5161.  
  5162.  
  5163. 2.1 Address Format
  5164.  
  5165. In MAPOS network, each end node has a unique HDLC address. As shown
  5166. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  5167. indicates the end of the field. When a SONET switch receives an HDLC
  5168. frame, it forwards the frame based on the address in the frame
  5169. header.
  5170.  
  5171. In unicast, MSB is 0 and the rest of the bits are the port number to
  5172. which a node is connected. Since the LSB is always 1, the minimum and
  5173. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  5174. reserved and is assigned to the control processor in a SONET switch.
  5175.  
  5176. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  5177. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  5178. indicate the group address.
  5179.  
  5180. +-------------+-+
  5181. | | | | | | | | |
  5182. | |port number|1|
  5183. +-+-----------+-+
  5184. ^ ^
  5185. | |
  5186. | +------- EA bit (always 1)
  5187. |
  5188. 1 : broadcast, multicast
  5189. 0 : unicast
  5190.  
  5191. Figure 1 Address format
  5192.  
  5193. 2.2 Address in multi-switch environment
  5194.  
  5195. In a multi-switch environment, variable-length subnet addressing is
  5196. used. Each switch has a switch number that is unique within the
  5197. system. Subnetted node addresses consist of the switch number and the
  5198. port number to which a node is connected. The address format is "0
  5199. <switch number> <node number> 1" for a unicast address, "all 1" for
  5200. the broadcast address, and "1 <group address> 1" for a multicast
  5201. address.
  5202.  
  5203. The address 0x01 is reserved and is assigned to the control processor
  5204. in the "local" switch. That is, it indicates the switch itself to
  5205. which the node is connected. The addresses of the form "0 <switch
  5206. number> <all 0> 1" are reserved, and indicates the control processor
  5207. of the switch designated by the switch number.
  5208.  
  5209. In Figure 2, the switch numbers are two bits long. Node N1 is
  5210. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  5211.  
  5212.  
  5213.  
  5214. Murakami & Maruyama Informational [Page 2]
  5216. RFC 2173 MAPOS June 1997
  5217.  
  5218.  
  5219. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  5220. has an address 01001001(0x49), since the switch number of S2 is 0x2
  5221. (10 in binary) and the port number is 0x09. Note that all the port
  5222. numbers are odd because the LSBs are always 1.
  5223.  
  5224. +------+
  5225. | node |
  5226. | N1 |
  5227. +------+
  5228. | 00100011(0x23)
  5229. |
  5230. |0x3 |0x3
  5231. +------+ +---+----+ +---+----+ +------+
  5232. | node +----+ SONET +-------+ SONET +-----+ node |
  5233. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  5234. +------+ | S1 | | S2 | +------+
  5235. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  5236. +---+----+ +---+----+
  5237. |0x7 |0x7
  5238.  
  5239.  
  5240. Figure 2 Addressing in Multiple Switch Environment
  5241.  
  5242. 4 NSP(Node-Switch Protocol)
  5243.  
  5244. This section describes the NSP protocol used for automatic node
  5245. address assignment.
  5246.  
  5247. 4.1 NSP protocol
  5248.  
  5249. NSP is introduced to provide an automatic node address assignment
  5250. function in MAPOS version 1. It reduces the administrative overhead
  5251. of node address configuration for each node and prevents troubles
  5252. such as address inconsistency and collision. When a node is connected
  5253. to a switch and receives SONET signal correctly, the node sends an
  5254. address request packet to the control processor in the local switch.
  5255. The destination address of this packet is 00000001(0x01). When the
  5256. control processor receives the packet, it replies with an address
  5257. assignment packet. The destination is the assigned node address. If
  5258. the node does not receive the address assignment packet within 5
  5259. seconds, it retransmits the address request packet. The
  5260. retransmission continues until the node successfully receives the
  5261. address assignment packet.
  5262.  
  5263. Whenever a node detects a transmission error such as carrier loss or
  5264. out-of-synchronization, it SHOULD send an address request packet to
  5265. the control processor and verify its current address. In addition, a
  5266. node MUST verify its address by sending address request packets every
  5267.  
  5268.  
  5269.  
  5270. Murakami & Maruyama Informational [Page 3]
  5272. RFC 2173 MAPOS June 1997
  5273.  
  5274.  
  5275. 30 seconds. The switch regards them as keep-alive packets and
  5276. utilizes them to detect the node's status. If it has not received a
  5277. request packet for more than 90 seconds, it assumes that the node
  5278. went down. In addition, it also assumes the node went down when a
  5279. switch detects a SONET signal failure.
  5280.  
  5281. 4.2 Packet Format
  5282.  
  5283. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  5284. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  5285. information field contains the NSP packet as shown in Figure 3.
  5286.  
  5287.  
  5288. +-----------+------------+
  5289. I command I address I
  5290. +-----------+------------+
  5291. I<- 32bit ->I<- 32 bit ->I
  5292.  
  5293. Figure 3 NSP packet format
  5294.  
  5295. The command field is 32 bits long and has the following values (in
  5296. decimal);
  5297.  
  5298. 1 address request
  5299. 2 address assignment
  5300. 3 reject(error)
  5301.  
  5302. The length of the address field is 32bits. In address request
  5303. packets, the NSP address field SHOULD be filled with zeroes, although
  5304. the switch ignores it. In address assignment packets, the assigned
  5305. address is placed in the least significant byte of the field. The
  5306. rest of the field is padded with zeroes. When the switch can not
  5307. assign the address for some reason, the switch replies with a reject
  5308. command (the values is 3). The value of the address field is
  5309. undefined.
  5310.  
  5311. 4.3 Consideration for special cases
  5312.  
  5313. There are two special cases to consider. One is a point-to-point
  5314. connection without a switch. The other is loop-back, that is, direct
  5315. connection between the input and the output of the same port.
  5316.  
  5317. 4.3.1 point-to-point
  5318.  
  5319. In the case of a point-to-point connection shown in Figure 4, a node
  5320. sends an address request packet to the other node. The destination
  5321. address is 00000001(0x01), that is usually a control processor in a
  5322. switch. When a node receives the address request, it detects the
  5323.  
  5324.  
  5325.  
  5326. Murakami & Maruyama Informational [Page 4]
  5328. RFC 2173 MAPOS June 1997
  5329.  
  5330.  
  5331. point-to-point connection by examining both the destination address
  5332. and the command contained. Then, it MUST reply with an address
  5333. assignment packet. The assigned address MUST be 00000011(0x03). Since
  5334. both nodes send an address request to each other, both of them get
  5335. address 00000011(0x03). Since any address can be used in point-to-
  5336. point environment, there is no problem even if both of the nodes have
  5337. the same address.
  5338.  
  5339. ---- address request ----> 0x01
  5340. 0x03 <---- address assignment ----
  5341. +------+ +------+
  5342. | node +--------------------------------+ node |
  5343. +------+ +------+
  5344. 0x01 <---- address request ----
  5345. ---- address assignment ----> 0x03
  5346.  
  5347. Figure 4 Point-to-point connection
  5348.  
  5349. 4.3.2 loop-back
  5350.  
  5351. Another special case is loop-back where the output port of a node is
  5352. simply connected to its input port as shown in Figure 5. In this
  5353. case, the same mechanism as that for point-to-point can be applied
  5354. without modification. A node sends an address request packet
  5355. destined to 00000001(0x01). The node then receives the same packet.
  5356. Since the destination is 00000001(0x01), it replies with an address
  5357. assignment packet, containing the assigned address 00000011(0x03), to
  5358. the address 0000 0011(0x03). Thus, the node obtains the address
  5359. 00000011(0x03).
  5360.  
  5361. ---- address request ----> 0x01
  5362. +------+ --- address assignment --> 0x03
  5363. | +-------------->-----------------+
  5364. | node + |
  5365. | +--------------<-----------------+
  5366. +------+
  5367.  
  5368. Figure 5 Loop-back Configuration
  5369.  
  5370.  
  5371.  
  5372.  
  5373.  
  5374.  
  5375.  
  5376.  
  5377.  
  5378.  
  5379.  
  5380.  
  5381.  
  5382. Murakami & Maruyama Informational [Page 5]
  5384. RFC 2173 MAPOS June 1997
  5385.  
  5386.  
  5387. 5. Security Considerations
  5388.  
  5389. Security issues are not discussed in this memo.
  5390.  
  5391. References
  5392.  
  5393. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  5394. over SONET/SDH, Version 1," RFC-2171, June 1997.
  5395.  
  5396. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  5397. Rates (1990).
  5398.  
  5399. [3] CCITT Recommendation G.708: Network Node Interface for
  5400. Synchronous Digital Hierarchy (1990).
  5401.  
  5402. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  5403. (1990).
  5404.  
  5405. [5] American National Standard for Telecommunications - Digital
  5406. Hierarchy - Optical Interface Rates and Formats Specification,
  5407. ANSI T1.105-1991.
  5408.  
  5409. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  5410. Numbers," RFC-2172, June, 1997.
  5411.  
  5412. Acknowledgements
  5413.  
  5414. The authors would like to acknowledge the contributions and
  5415. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  5416. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  5417.  
  5418. Authors' Address
  5419.  
  5420. Ken Murakami
  5421. NTT Software Laboratories
  5422. 3-9-11, Midori-cho
  5423. Musashino-shi
  5424. Tokyo 180, Japan
  5425. E-mail: murakami@ntt-20.ecl.net
  5426.  
  5427. Mitsuru Maruyama
  5428. NTT Software Laboratories
  5429. 3-9-11, Midori-cho
  5430. Musashino-shi
  5431. Tokyo 180, Japan
  5432. E-mail: mitsuru@ntt-20.ecl.net
  5433.  
  5434.  
  5435.  
  5436.  
  5437.  
  5438. Murakami & Maruyama Informational [Page 6]
  5440.  
  5441.  
  5442.  
  5443.  
  5444.  
  5445.  
  5446.  
  5447. Network Working Group K. Murakami
  5448. Request for Comments: 2173 M. Maruyama
  5449. Category: Informational NTT Laboratories
  5450. June 1997
  5451.  
  5452.  
  5453. A MAPOS version 1 Extension - Node Switch Protocol
  5454.  
  5455. Status of this Memo
  5456.  
  5457. This memo provides information for the Internet community. This memo
  5458. does not specify an Internet standard of any kind. Distribution of
  5459. this memo is unlimited.
  5460.  
  5461. Abstract
  5462.  
  5463. This document describes a MAPOS extension, Node Switch Protocol, for
  5464. automatic node address assignment. MAPOS is a multiple access
  5465. protocol for transmission of network-protocol datagrams, encapsulated
  5466. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  5467. automates the HDLC address configuration of each node. Using NSP, a
  5468. node retrieves its HDLC address from the switch to which it is
  5469. connected.
  5470.  
  5471. 1. Introduction
  5472.  
  5473. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  5474. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  5475. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  5476. switch provides multiple access capability to each node. In MAPOS,
  5477. each node has a unique HDLC address within a switch. The address is
  5478. equivalent to the port number of the switch to which the node is
  5479. connected. This document describes an extension to MAPOS, Node
  5480. Switch Protocol, which enable automatic HDLC address assignment.
  5481. First, it explains the addressing of MAPOS. Then, it describes the
  5482. NSP protocol for automatic HDLC node address assignment.
  5483.  
  5484. 2. Node Address Format
  5485.  
  5486. This section describes MAPOS Version 1 address format in single and
  5487. multiple switch environment.
  5488.  
  5489.  
  5490.  
  5491.  
  5492.  
  5493.  
  5494.  
  5495.  
  5496.  
  5497.  
  5498. Murakami & Maruyama Informational [Page 1]
  5500. RFC 2173 MAPOS June 1997
  5501.  
  5502.  
  5503. 2.1 Address Format
  5504.  
  5505. In MAPOS network, each end node has a unique HDLC address. As shown
  5506. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  5507. indicates the end of the field. When a SONET switch receives an HDLC
  5508. frame, it forwards the frame based on the address in the frame
  5509. header.
  5510.  
  5511. In unicast, MSB is 0 and the rest of the bits are the port number to
  5512. which a node is connected. Since the LSB is always 1, the minimum and
  5513. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  5514. reserved and is assigned to the control processor in a SONET switch.
  5515.  
  5516. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  5517. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  5518. indicate the group address.
  5519.  
  5520. +-------------+-+
  5521. | | | | | | | | |
  5522. | |port number|1|
  5523. +-+-----------+-+
  5524. ^ ^
  5525. | |
  5526. | +------- EA bit (always 1)
  5527. |
  5528. 1 : broadcast, multicast
  5529. 0 : unicast
  5530.  
  5531. Figure 1 Address format
  5532.  
  5533. 2.2 Address in multi-switch environment
  5534.  
  5535. In a multi-switch environment, variable-length subnet addressing is
  5536. used. Each switch has a switch number that is unique within the
  5537. system. Subnetted node addresses consist of the switch number and the
  5538. port number to which a node is connected. The address format is "0
  5539. <switch number> <node number> 1" for a unicast address, "all 1" for
  5540. the broadcast address, and "1 <group address> 1" for a multicast
  5541. address.
  5542.  
  5543. The address 0x01 is reserved and is assigned to the control processor
  5544. in the "local" switch. That is, it indicates the switch itself to
  5545. which the node is connected. The addresses of the form "0 <switch
  5546. number> <all 0> 1" are reserved, and indicates the control processor
  5547. of the switch designated by the switch number.
  5548.  
  5549. In Figure 2, the switch numbers are two bits long. Node N1 is
  5550. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  5551.  
  5552.  
  5553.  
  5554. Murakami & Maruyama Informational [Page 2]
  5556. RFC 2173 MAPOS June 1997
  5557.  
  5558.  
  5559. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  5560. has an address 01001001(0x49), since the switch number of S2 is 0x2
  5561. (10 in binary) and the port number is 0x09. Note that all the port
  5562. numbers are odd because the LSBs are always 1.
  5563.  
  5564. +------+
  5565. | node |
  5566. | N1 |
  5567. +------+
  5568. | 00100011(0x23)
  5569. |
  5570. |0x3 |0x3
  5571. +------+ +---+----+ +---+----+ +------+
  5572. | node +----+ SONET +-------+ SONET +-----+ node |
  5573. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  5574. +------+ | S1 | | S2 | +------+
  5575. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  5576. +---+----+ +---+----+
  5577. |0x7 |0x7
  5578.  
  5579.  
  5580. Figure 2 Addressing in Multiple Switch Environment
  5581.  
  5582. 4 NSP(Node-Switch Protocol)
  5583.  
  5584. This section describes the NSP protocol used for automatic node
  5585. address assignment.
  5586.  
  5587. 4.1 NSP protocol
  5588.  
  5589. NSP is introduced to provide an automatic node address assignment
  5590. function in MAPOS version 1. It reduces the administrative overhead
  5591. of node address configuration for each node and prevents troubles
  5592. such as address inconsistency and collision. When a node is connected
  5593. to a switch and receives SONET signal correctly, the node sends an
  5594. address request packet to the control processor in the local switch.
  5595. The destination address of this packet is 00000001(0x01). When the
  5596. control processor receives the packet, it replies with an address
  5597. assignment packet. The destination is the assigned node address. If
  5598. the node does not receive the address assignment packet within 5
  5599. seconds, it retransmits the address request packet. The
  5600. retransmission continues until the node successfully receives the
  5601. address assignment packet.
  5602.  
  5603. Whenever a node detects a transmission error such as carrier loss or
  5604. out-of-synchronization, it SHOULD send an address request packet to
  5605. the control processor and verify its current address. In addition, a
  5606. node MUST verify its address by sending address request packets every
  5607.  
  5608.  
  5609.  
  5610. Murakami & Maruyama Informational [Page 3]
  5612. RFC 2173 MAPOS June 1997
  5613.  
  5614.  
  5615. 30 seconds. The switch regards them as keep-alive packets and
  5616. utilizes them to detect the node's status. If it has not received a
  5617. request packet for more than 90 seconds, it assumes that the node
  5618. went down. In addition, it also assumes the node went down when a
  5619. switch detects a SONET signal failure.
  5620.  
  5621. 4.2 Packet Format
  5622.  
  5623. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  5624. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  5625. information field contains the NSP packet as shown in Figure 3.
  5626.  
  5627.  
  5628. +-----------+------------+
  5629. I command I address I
  5630. +-----------+------------+
  5631. I<- 32bit ->I<- 32 bit ->I
  5632.  
  5633. Figure 3 NSP packet format
  5634.  
  5635. The command field is 32 bits long and has the following values (in
  5636. decimal);
  5637.  
  5638. 1 address request
  5639. 2 address assignment
  5640. 3 reject(error)
  5641.  
  5642. The length of the address field is 32bits. In address request
  5643. packets, the NSP address field SHOULD be filled with zeroes, although
  5644. the switch ignores it. In address assignment packets, the assigned
  5645. address is placed in the least significant byte of the field. The
  5646. rest of the field is padded with zeroes. When the switch can not
  5647. assign the address for some reason, the switch replies with a reject
  5648. command (the values is 3). The value of the address field is
  5649. undefined.
  5650.  
  5651. 4.3 Consideration for special cases
  5652.  
  5653. There are two special cases to consider. One is a point-to-point
  5654. connection without a switch. The other is loop-back, that is, direct
  5655. connection between the input and the output of the same port.
  5656.  
  5657. 4.3.1 point-to-point
  5658.  
  5659. In the case of a point-to-point connection shown in Figure 4, a node
  5660. sends an address request packet to the other node. The destination
  5661. address is 00000001(0x01), that is usually a control processor in a
  5662. switch. When a node receives the address request, it detects the
  5663.  
  5664.  
  5665.  
  5666. Murakami & Maruyama Informational [Page 4]
  5668. RFC 2173 MAPOS June 1997
  5669.  
  5670.  
  5671. point-to-point connection by examining both the destination address
  5672. and the command contained. Then, it MUST reply with an address
  5673. assignment packet. The assigned address MUST be 00000011(0x03). Since
  5674. both nodes send an address request to each other, both of them get
  5675. address 00000011(0x03). Since any address can be used in point-to-
  5676. point environment, there is no problem even if both of the nodes have
  5677. the same address.
  5678.  
  5679. ---- address request ----> 0x01
  5680. 0x03 <---- address assignment ----
  5681. +------+ +------+
  5682. | node +--------------------------------+ node |
  5683. +------+ +------+
  5684. 0x01 <---- address request ----
  5685. ---- address assignment ----> 0x03
  5686.  
  5687. Figure 4 Point-to-point connection
  5688.  
  5689. 4.3.2 loop-back
  5690.  
  5691. Another special case is loop-back where the output port of a node is
  5692. simply connected to its input port as shown in Figure 5. In this
  5693. case, the same mechanism as that for point-to-point can be applied
  5694. without modification. A node sends an address request packet
  5695. destined to 00000001(0x01). The node then receives the same packet.
  5696. Since the destination is 00000001(0x01), it replies with an address
  5697. assignment packet, containing the assigned address 00000011(0x03), to
  5698. the address 0000 0011(0x03). Thus, the node obtains the address
  5699. 00000011(0x03).
  5700.  
  5701. ---- address request ----> 0x01
  5702. +------+ --- address assignment --> 0x03
  5703. | +-------------->-----------------+
  5704. | node + |
  5705. | +--------------<-----------------+
  5706. +------+
  5707.  
  5708. Figure 5 Loop-back Configuration
  5709.  
  5710.  
  5711.  
  5712.  
  5713.  
  5714.  
  5715.  
  5716.  
  5717.  
  5718.  
  5719.  
  5720.  
  5721.  
  5722. Murakami & Maruyama Informational [Page 5]
  5724. RFC 2173 MAPOS June 1997
  5725.  
  5726.  
  5727. 5. Security Considerations
  5728.  
  5729. Security issues are not discussed in this memo.
  5730.  
  5731. References
  5732.  
  5733. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  5734. over SONET/SDH, Version 1," RFC-2171, June 1997.
  5735.  
  5736. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  5737. Rates (1990).
  5738.  
  5739. [3] CCITT Recommendation G.708: Network Node Interface for
  5740. Synchronous Digital Hierarchy (1990).
  5741.  
  5742. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  5743. (1990).
  5744.  
  5745. [5] American National Standard for Telecommunications - Digital
  5746. Hierarchy - Optical Interface Rates and Formats Specification,
  5747. ANSI T1.105-1991.
  5748.  
  5749. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  5750. Numbers," RFC-2172, June, 1997.
  5751.  
  5752. Acknowledgements
  5753.  
  5754. The authors would like to acknowledge the contributions and
  5755. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  5756. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  5757.  
  5758. Authors' Address
  5759.  
  5760. Ken Murakami
  5761. NTT Software Laboratories
  5762. 3-9-11, Midori-cho
  5763. Musashino-shi
  5764. Tokyo 180, Japan
  5765. E-mail: murakami@ntt-20.ecl.net
  5766.  
  5767. Mitsuru Maruyama
  5768. NTT Software Laboratories
  5769. 3-9-11, Midori-cho
  5770. Musashino-shi
  5771. Tokyo 180, Japan
  5772. E-mail: mitsuru@ntt-20.ecl.net
  5773.  
  5774.  
  5775.  
  5776.  
  5777.  
  5778. Murakami & Maruyama Informational [Page 6]
  5780.  
  5781.  
  5782.  
  5783.  
  5784.  
  5785.  
  5786.  
  5787. Network Working Group K. Murakami
  5788. Request for Comments: 2173 M. Maruyama
  5789. Category: Informational NTT Laboratories
  5790. June 1997
  5791.  
  5792.  
  5793. A MAPOS version 1 Extension - Node Switch Protocol
  5794.  
  5795. Status of this Memo
  5796.  
  5797. This memo provides information for the Internet community. This memo
  5798. does not specify an Internet standard of any kind. Distribution of
  5799. this memo is unlimited.
  5800.  
  5801. Abstract
  5802.  
  5803. This document describes a MAPOS extension, Node Switch Protocol, for
  5804. automatic node address assignment. MAPOS is a multiple access
  5805. protocol for transmission of network-protocol datagrams, encapsulated
  5806. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  5807. automates the HDLC address configuration of each node. Using NSP, a
  5808. node retrieves its HDLC address from the switch to which it is
  5809. connected.
  5810.  
  5811. 1. Introduction
  5812.  
  5813. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  5814. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  5815. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  5816. switch provides multiple access capability to each node. In MAPOS,
  5817. each node has a unique HDLC address within a switch. The address is
  5818. equivalent to the port number of the switch to which the node is
  5819. connected. This document describes an extension to MAPOS, Node
  5820. Switch Protocol, which enable automatic HDLC address assignment.
  5821. First, it explains the addressing of MAPOS. Then, it describes the
  5822. NSP protocol for automatic HDLC node address assignment.
  5823.  
  5824. 2. Node Address Format
  5825.  
  5826. This section describes MAPOS Version 1 address format in single and
  5827. multiple switch environment.
  5828.  
  5829.  
  5830.  
  5831.  
  5832.  
  5833.  
  5834.  
  5835.  
  5836.  
  5837.  
  5838. Murakami & Maruyama Informational [Page 1]
  5840. RFC 2173 MAPOS June 1997
  5841.  
  5842.  
  5843. 2.1 Address Format
  5844.  
  5845. In MAPOS network, each end node has a unique HDLC address. As shown
  5846. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  5847. indicates the end of the field. When a SONET switch receives an HDLC
  5848. frame, it forwards the frame based on the address in the frame
  5849. header.
  5850.  
  5851. In unicast, MSB is 0 and the rest of the bits are the port number to
  5852. which a node is connected. Since the LSB is always 1, the minimum and
  5853. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  5854. reserved and is assigned to the control processor in a SONET switch.
  5855.  
  5856. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  5857. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  5858. indicate the group address.
  5859.  
  5860. +-------------+-+
  5861. | | | | | | | | |
  5862. | |port number|1|
  5863. +-+-----------+-+
  5864. ^ ^
  5865. | |
  5866. | +------- EA bit (always 1)
  5867. |
  5868. 1 : broadcast, multicast
  5869. 0 : unicast
  5870.  
  5871. Figure 1 Address format
  5872.  
  5873. 2.2 Address in multi-switch environment
  5874.  
  5875. In a multi-switch environment, variable-length subnet addressing is
  5876. used. Each switch has a switch number that is unique within the
  5877. system. Subnetted node addresses consist of the switch number and the
  5878. port number to which a node is connected. The address format is "0
  5879. <switch number> <node number> 1" for a unicast address, "all 1" for
  5880. the broadcast address, and "1 <group address> 1" for a multicast
  5881. address.
  5882.  
  5883. The address 0x01 is reserved and is assigned to the control processor
  5884. in the "local" switch. That is, it indicates the switch itself to
  5885. which the node is connected. The addresses of the form "0 <switch
  5886. number> <all 0> 1" are reserved, and indicates the control processor
  5887. of the switch designated by the switch number.
  5888.  
  5889. In Figure 2, the switch numbers are two bits long. Node N1 is
  5890. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  5891.  
  5892.  
  5893.  
  5894. Murakami & Maruyama Informational [Page 2]
  5896. RFC 2173 MAPOS June 1997
  5897.  
  5898.  
  5899. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  5900. has an address 01001001(0x49), since the switch number of S2 is 0x2
  5901. (10 in binary) and the port number is 0x09. Note that all the port
  5902. numbers are odd because the LSBs are always 1.
  5903.  
  5904. +------+
  5905. | node |
  5906. | N1 |
  5907. +------+
  5908. | 00100011(0x23)
  5909. |
  5910. |0x3 |0x3
  5911. +------+ +---+----+ +---+----+ +------+
  5912. | node +----+ SONET +-------+ SONET +-----+ node |
  5913. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  5914. +------+ | S1 | | S2 | +------+
  5915. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  5916. +---+----+ +---+----+
  5917. |0x7 |0x7
  5918.  
  5919.  
  5920. Figure 2 Addressing in Multiple Switch Environment
  5921.  
  5922. 4 NSP(Node-Switch Protocol)
  5923.  
  5924. This section describes the NSP protocol used for automatic node
  5925. address assignment.
  5926.  
  5927. 4.1 NSP protocol
  5928.  
  5929. NSP is introduced to provide an automatic node address assignment
  5930. function in MAPOS version 1. It reduces the administrative overhead
  5931. of node address configuration for each node and prevents troubles
  5932. such as address inconsistency and collision. When a node is connected
  5933. to a switch and receives SONET signal correctly, the node sends an
  5934. address request packet to the control processor in the local switch.
  5935. The destination address of this packet is 00000001(0x01). When the
  5936. control processor receives the packet, it replies with an address
  5937. assignment packet. The destination is the assigned node address. If
  5938. the node does not receive the address assignment packet within 5
  5939. seconds, it retransmits the address request packet. The
  5940. retransmission continues until the node successfully receives the
  5941. address assignment packet.
  5942.  
  5943. Whenever a node detects a transmission error such as carrier loss or
  5944. out-of-synchronization, it SHOULD send an address request packet to
  5945. the control processor and verify its current address. In addition, a
  5946. node MUST verify its address by sending address request packets every
  5947.  
  5948.  
  5949.  
  5950. Murakami & Maruyama Informational [Page 3]
  5952. RFC 2173 MAPOS June 1997
  5953.  
  5954.  
  5955. 30 seconds. The switch regards them as keep-alive packets and
  5956. utilizes them to detect the node's status. If it has not received a
  5957. request packet for more than 90 seconds, it assumes that the node
  5958. went down. In addition, it also assumes the node went down when a
  5959. switch detects a SONET signal failure.
  5960.  
  5961. 4.2 Packet Format
  5962.  
  5963. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  5964. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  5965. information field contains the NSP packet as shown in Figure 3.
  5966.  
  5967.  
  5968. +-----------+------------+
  5969. I command I address I
  5970. +-----------+------------+
  5971. I<- 32bit ->I<- 32 bit ->I
  5972.  
  5973. Figure 3 NSP packet format
  5974.  
  5975. The command field is 32 bits long and has the following values (in
  5976. decimal);
  5977.  
  5978. 1 address request
  5979. 2 address assignment
  5980. 3 reject(error)
  5981.  
  5982. The length of the address field is 32bits. In address request
  5983. packets, the NSP address field SHOULD be filled with zeroes, although
  5984. the switch ignores it. In address assignment packets, the assigned
  5985. address is placed in the least significant byte of the field. The
  5986. rest of the field is padded with zeroes. When the switch can not
  5987. assign the address for some reason, the switch replies with a reject
  5988. command (the values is 3). The value of the address field is
  5989. undefined.
  5990.  
  5991. 4.3 Consideration for special cases
  5992.  
  5993. There are two special cases to consider. One is a point-to-point
  5994. connection without a switch. The other is loop-back, that is, direct
  5995. connection between the input and the output of the same port.
  5996.  
  5997. 4.3.1 point-to-point
  5998.  
  5999. In the case of a point-to-point connection shown in Figure 4, a node
  6000. sends an address request packet to the other node. The destination
  6001. address is 00000001(0x01), that is usually a control processor in a
  6002. switch. When a node receives the address request, it detects the
  6003.  
  6004.  
  6005.  
  6006. Murakami & Maruyama Informational [Page 4]
  6008. RFC 2173 MAPOS June 1997
  6009.  
  6010.  
  6011. point-to-point connection by examining both the destination address
  6012. and the command contained. Then, it MUST reply with an address
  6013. assignment packet. The assigned address MUST be 00000011(0x03). Since
  6014. both nodes send an address request to each other, both of them get
  6015. address 00000011(0x03). Since any address can be used in point-to-
  6016. point environment, there is no problem even if both of the nodes have
  6017. the same address.
  6018.  
  6019. ---- address request ----> 0x01
  6020. 0x03 <---- address assignment ----
  6021. +------+ +------+
  6022. | node +--------------------------------+ node |
  6023. +------+ +------+
  6024. 0x01 <---- address request ----
  6025. ---- address assignment ----> 0x03
  6026.  
  6027. Figure 4 Point-to-point connection
  6028.  
  6029. 4.3.2 loop-back
  6030.  
  6031. Another special case is loop-back where the output port of a node is
  6032. simply connected to its input port as shown in Figure 5. In this
  6033. case, the same mechanism as that for point-to-point can be applied
  6034. without modification. A node sends an address request packet
  6035. destined to 00000001(0x01). The node then receives the same packet.
  6036. Since the destination is 00000001(0x01), it replies with an address
  6037. assignment packet, containing the assigned address 00000011(0x03), to
  6038. the address 0000 0011(0x03). Thus, the node obtains the address
  6039. 00000011(0x03).
  6040.  
  6041. ---- address request ----> 0x01
  6042. +------+ --- address assignment --> 0x03
  6043. | +-------------->-----------------+
  6044. | node + |
  6045. | +--------------<-----------------+
  6046. +------+
  6047.  
  6048. Figure 5 Loop-back Configuration
  6049.  
  6050.  
  6051.  
  6052.  
  6053.  
  6054.  
  6055.  
  6056.  
  6057.  
  6058.  
  6059.  
  6060.  
  6061.  
  6062. Murakami & Maruyama Informational [Page 5]
  6064. RFC 2173 MAPOS June 1997
  6065.  
  6066.  
  6067. 5. Security Considerations
  6068.  
  6069. Security issues are not discussed in this memo.
  6070.  
  6071. References
  6072.  
  6073. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  6074. over SONET/SDH, Version 1," RFC-2171, June 1997.
  6075.  
  6076. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  6077. Rates (1990).
  6078.  
  6079. [3] CCITT Recommendation G.708: Network Node Interface for
  6080. Synchronous Digital Hierarchy (1990).
  6081.  
  6082. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  6083. (1990).
  6084.  
  6085. [5] American National Standard for Telecommunications - Digital
  6086. Hierarchy - Optical Interface Rates and Formats Specification,
  6087. ANSI T1.105-1991.
  6088.  
  6089. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  6090. Numbers," RFC-2172, June, 1997.
  6091.  
  6092. Acknowledgements
  6093.  
  6094. The authors would like to acknowledge the contributions and
  6095. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  6096. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  6097.  
  6098. Authors' Address
  6099.  
  6100. Ken Murakami
  6101. NTT Software Laboratories
  6102. 3-9-11, Midori-cho
  6103. Musashino-shi
  6104. Tokyo 180, Japan
  6105. E-mail: murakami@ntt-20.ecl.net
  6106.  
  6107. Mitsuru Maruyama
  6108. NTT Software Laboratories
  6109. 3-9-11, Midori-cho
  6110. Musashino-shi
  6111. Tokyo 180, Japan
  6112. E-mail: mitsuru@ntt-20.ecl.net
  6113.  
  6114.  
  6115.  
  6116.  
  6117.  
  6118. Murakami & Maruyama Informational [Page 6]
  6120.  
  6121.  
  6122.  
  6123.  
  6124.  
  6125.  
  6126.  
  6127. Network Working Group K. Murakami
  6128. Request for Comments: 2173 M. Maruyama
  6129. Category: Informational NTT Laboratories
  6130. June 1997
  6131.  
  6132.  
  6133. A MAPOS version 1 Extension - Node Switch Protocol
  6134.  
  6135. Status of this Memo
  6136.  
  6137. This memo provides information for the Internet community. This memo
  6138. does not specify an Internet standard of any kind. Distribution of
  6139. this memo is unlimited.
  6140.  
  6141. Abstract
  6142.  
  6143. This document describes a MAPOS extension, Node Switch Protocol, for
  6144. automatic node address assignment. MAPOS is a multiple access
  6145. protocol for transmission of network-protocol datagrams, encapsulated
  6146. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  6147. automates the HDLC address configuration of each node. Using NSP, a
  6148. node retrieves its HDLC address from the switch to which it is
  6149. connected.
  6150.  
  6151. 1. Introduction
  6152.  
  6153. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  6154. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  6155. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  6156. switch provides multiple access capability to each node. In MAPOS,
  6157. each node has a unique HDLC address within a switch. The address is
  6158. equivalent to the port number of the switch to which the node is
  6159. connected. This document describes an extension to MAPOS, Node
  6160. Switch Protocol, which enable automatic HDLC address assignment.
  6161. First, it explains the addressing of MAPOS. Then, it describes the
  6162. NSP protocol for automatic HDLC node address assignment.
  6163.  
  6164. 2. Node Address Format
  6165.  
  6166. This section describes MAPOS Version 1 address format in single and
  6167. multiple switch environment.
  6168.  
  6169.  
  6170.  
  6171.  
  6172.  
  6173.  
  6174.  
  6175.  
  6176.  
  6177.  
  6178. Murakami & Maruyama Informational [Page 1]
  6180. RFC 2173 MAPOS June 1997
  6181.  
  6182.  
  6183. 2.1 Address Format
  6184.  
  6185. In MAPOS network, each end node has a unique HDLC address. As shown
  6186. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  6187. indicates the end of the field. When a SONET switch receives an HDLC
  6188. frame, it forwards the frame based on the address in the frame
  6189. header.
  6190.  
  6191. In unicast, MSB is 0 and the rest of the bits are the port number to
  6192. which a node is connected. Since the LSB is always 1, the minimum and
  6193. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  6194. reserved and is assigned to the control processor in a SONET switch.
  6195.  
  6196. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  6197. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  6198. indicate the group address.
  6199.  
  6200. +-------------+-+
  6201. | | | | | | | | |
  6202. | |port number|1|
  6203. +-+-----------+-+
  6204. ^ ^
  6205. | |
  6206. | +------- EA bit (always 1)
  6207. |
  6208. 1 : broadcast, multicast
  6209. 0 : unicast
  6210.  
  6211. Figure 1 Address format
  6212.  
  6213. 2.2 Address in multi-switch environment
  6214.  
  6215. In a multi-switch environment, variable-length subnet addressing is
  6216. used. Each switch has a switch number that is unique within the
  6217. system. Subnetted node addresses consist of the switch number and the
  6218. port number to which a node is connected. The address format is "0
  6219. <switch number> <node number> 1" for a unicast address, "all 1" for
  6220. the broadcast address, and "1 <group address> 1" for a multicast
  6221. address.
  6222.  
  6223. The address 0x01 is reserved and is assigned to the control processor
  6224. in the "local" switch. That is, it indicates the switch itself to
  6225. which the node is connected. The addresses of the form "0 <switch
  6226. number> <all 0> 1" are reserved, and indicates the control processor
  6227. of the switch designated by the switch number.
  6228.  
  6229. In Figure 2, the switch numbers are two bits long. Node N1 is
  6230. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  6231.  
  6232.  
  6233.  
  6234. Murakami & Maruyama Informational [Page 2]
  6236. RFC 2173 MAPOS June 1997
  6237.  
  6238.  
  6239. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  6240. has an address 01001001(0x49), since the switch number of S2 is 0x2
  6241. (10 in binary) and the port number is 0x09. Note that all the port
  6242. numbers are odd because the LSBs are always 1.
  6243.  
  6244. +------+
  6245. | node |
  6246. | N1 |
  6247. +------+
  6248. | 00100011(0x23)
  6249. |
  6250. |0x3 |0x3
  6251. +------+ +---+----+ +---+----+ +------+
  6252. | node +----+ SONET +-------+ SONET +-----+ node |
  6253. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  6254. +------+ | S1 | | S2 | +------+
  6255. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  6256. +---+----+ +---+----+
  6257. |0x7 |0x7
  6258.  
  6259.  
  6260. Figure 2 Addressing in Multiple Switch Environment
  6261.  
  6262. 4 NSP(Node-Switch Protocol)
  6263.  
  6264. This section describes the NSP protocol used for automatic node
  6265. address assignment.
  6266.  
  6267. 4.1 NSP protocol
  6268.  
  6269. NSP is introduced to provide an automatic node address assignment
  6270. function in MAPOS version 1. It reduces the administrative overhead
  6271. of node address configuration for each node and prevents troubles
  6272. such as address inconsistency and collision. When a node is connected
  6273. to a switch and receives SONET signal correctly, the node sends an
  6274. address request packet to the control processor in the local switch.
  6275. The destination address of this packet is 00000001(0x01). When the
  6276. control processor receives the packet, it replies with an address
  6277. assignment packet. The destination is the assigned node address. If
  6278. the node does not receive the address assignment packet within 5
  6279. seconds, it retransmits the address request packet. The
  6280. retransmission continues until the node successfully receives the
  6281. address assignment packet.
  6282.  
  6283. Whenever a node detects a transmission error such as carrier loss or
  6284. out-of-synchronization, it SHOULD send an address request packet to
  6285. the control processor and verify its current address. In addition, a
  6286. node MUST verify its address by sending address request packets every
  6287.  
  6288.  
  6289.  
  6290. Murakami & Maruyama Informational [Page 3]
  6292. RFC 2173 MAPOS June 1997
  6293.  
  6294.  
  6295. 30 seconds. The switch regards them as keep-alive packets and
  6296. utilizes them to detect the node's status. If it has not received a
  6297. request packet for more than 90 seconds, it assumes that the node
  6298. went down. In addition, it also assumes the node went down when a
  6299. switch detects a SONET signal failure.
  6300.  
  6301. 4.2 Packet Format
  6302.  
  6303. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  6304. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  6305. information field contains the NSP packet as shown in Figure 3.
  6306.  
  6307.  
  6308. +-----------+------------+
  6309. I command I address I
  6310. +-----------+------------+
  6311. I<- 32bit ->I<- 32 bit ->I
  6312.  
  6313. Figure 3 NSP packet format
  6314.  
  6315. The command field is 32 bits long and has the following values (in
  6316. decimal);
  6317.  
  6318. 1 address request
  6319. 2 address assignment
  6320. 3 reject(error)
  6321.  
  6322. The length of the address field is 32bits. In address request
  6323. packets, the NSP address field SHOULD be filled with zeroes, although
  6324. the switch ignores it. In address assignment packets, the assigned
  6325. address is placed in the least significant byte of the field. The
  6326. rest of the field is padded with zeroes. When the switch can not
  6327. assign the address for some reason, the switch replies with a reject
  6328. command (the values is 3). The value of the address field is
  6329. undefined.
  6330.  
  6331. 4.3 Consideration for special cases
  6332.  
  6333. There are two special cases to consider. One is a point-to-point
  6334. connection without a switch. The other is loop-back, that is, direct
  6335. connection between the input and the output of the same port.
  6336.  
  6337. 4.3.1 point-to-point
  6338.  
  6339. In the case of a point-to-point connection shown in Figure 4, a node
  6340. sends an address request packet to the other node. The destination
  6341. address is 00000001(0x01), that is usually a control processor in a
  6342. switch. When a node receives the address request, it detects the
  6343.  
  6344.  
  6345.  
  6346. Murakami & Maruyama Informational [Page 4]
  6348. RFC 2173 MAPOS June 1997
  6349.  
  6350.  
  6351. point-to-point connection by examining both the destination address
  6352. and the command contained. Then, it MUST reply with an address
  6353. assignment packet. The assigned address MUST be 00000011(0x03). Since
  6354. both nodes send an address request to each other, both of them get
  6355. address 00000011(0x03). Since any address can be used in point-to-
  6356. point environment, there is no problem even if both of the nodes have
  6357. the same address.
  6358.  
  6359. ---- address request ----> 0x01
  6360. 0x03 <---- address assignment ----
  6361. +------+ +------+
  6362. | node +--------------------------------+ node |
  6363. +------+ +------+
  6364. 0x01 <---- address request ----
  6365. ---- address assignment ----> 0x03
  6366.  
  6367. Figure 4 Point-to-point connection
  6368.  
  6369. 4.3.2 loop-back
  6370.  
  6371. Another special case is loop-back where the output port of a node is
  6372. simply connected to its input port as shown in Figure 5. In this
  6373. case, the same mechanism as that for point-to-point can be applied
  6374. without modification. A node sends an address request packet
  6375. destined to 00000001(0x01). The node then receives the same packet.
  6376. Since the destination is 00000001(0x01), it replies with an address
  6377. assignment packet, containing the assigned address 00000011(0x03), to
  6378. the address 0000 0011(0x03). Thus, the node obtains the address
  6379. 00000011(0x03).
  6380.  
  6381. ---- address request ----> 0x01
  6382. +------+ --- address assignment --> 0x03
  6383. | +-------------->-----------------+
  6384. | node + |
  6385. | +--------------<-----------------+
  6386. +------+
  6387.  
  6388. Figure 5 Loop-back Configuration
  6389.  
  6390.  
  6391.  
  6392.  
  6393.  
  6394.  
  6395.  
  6396.  
  6397.  
  6398.  
  6399.  
  6400.  
  6401.  
  6402. Murakami & Maruyama Informational [Page 5]
  6404. RFC 2173 MAPOS June 1997
  6405.  
  6406.  
  6407. 5. Security Considerations
  6408.  
  6409. Security issues are not discussed in this memo.
  6410.  
  6411. References
  6412.  
  6413. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  6414. over SONET/SDH, Version 1," RFC-2171, June 1997.
  6415.  
  6416. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  6417. Rates (1990).
  6418.  
  6419. [3] CCITT Recommendation G.708: Network Node Interface for
  6420. Synchronous Digital Hierarchy (1990).
  6421.  
  6422. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  6423. (1990).
  6424.  
  6425. [5] American National Standard for Telecommunications - Digital
  6426. Hierarchy - Optical Interface Rates and Formats Specification,
  6427. ANSI T1.105-1991.
  6428.  
  6429. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  6430. Numbers," RFC-2172, June, 1997.
  6431.  
  6432. Acknowledgements
  6433.  
  6434. The authors would like to acknowledge the contributions and
  6435. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  6436. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  6437.  
  6438. Authors' Address
  6439.  
  6440. Ken Murakami
  6441. NTT Software Laboratories
  6442. 3-9-11, Midori-cho
  6443. Musashino-shi
  6444. Tokyo 180, Japan
  6445. E-mail: murakami@ntt-20.ecl.net
  6446.  
  6447. Mitsuru Maruyama
  6448. NTT Software Laboratories
  6449. 3-9-11, Midori-cho
  6450. Musashino-shi
  6451. Tokyo 180, Japan
  6452. E-mail: mitsuru@ntt-20.ecl.net
  6453.  
  6454.  
  6455.  
  6456.  
  6457.  
  6458. Murakami & Maruyama Informational [Page 6]
  6460.  
  6461.  
  6462.  
  6463.  
  6464.  
  6465.  
  6466.  
  6467. Network Working Group K. Murakami
  6468. Request for Comments: 2173 M. Maruyama
  6469. Category: Informational NTT Laboratories
  6470. June 1997
  6471.  
  6472.  
  6473. A MAPOS version 1 Extension - Node Switch Protocol
  6474.  
  6475. Status of this Memo
  6476.  
  6477. This memo provides information for the Internet community. This memo
  6478. does not specify an Internet standard of any kind. Distribution of
  6479. this memo is unlimited.
  6480.  
  6481. Abstract
  6482.  
  6483. This document describes a MAPOS extension, Node Switch Protocol, for
  6484. automatic node address assignment. MAPOS is a multiple access
  6485. protocol for transmission of network-protocol datagrams, encapsulated
  6486. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  6487. automates the HDLC address configuration of each node. Using NSP, a
  6488. node retrieves its HDLC address from the switch to which it is
  6489. connected.
  6490.  
  6491. 1. Introduction
  6492.  
  6493. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  6494. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  6495. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  6496. switch provides multiple access capability to each node. In MAPOS,
  6497. each node has a unique HDLC address within a switch. The address is
  6498. equivalent to the port number of the switch to which the node is
  6499. connected. This document describes an extension to MAPOS, Node
  6500. Switch Protocol, which enable automatic HDLC address assignment.
  6501. First, it explains the addressing of MAPOS. Then, it describes the
  6502. NSP protocol for automatic HDLC node address assignment.
  6503.  
  6504. 2. Node Address Format
  6505.  
  6506. This section describes MAPOS Version 1 address format in single and
  6507. multiple switch environment.
  6508.  
  6509.  
  6510.  
  6511.  
  6512.  
  6513.  
  6514.  
  6515.  
  6516.  
  6517.  
  6518. Murakami & Maruyama Informational [Page 1]
  6520. RFC 2173 MAPOS June 1997
  6521.  
  6522.  
  6523. 2.1 Address Format
  6524.  
  6525. In MAPOS network, each end node has a unique HDLC address. As shown
  6526. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  6527. indicates the end of the field. When a SONET switch receives an HDLC
  6528. frame, it forwards the frame based on the address in the frame
  6529. header.
  6530.  
  6531. In unicast, MSB is 0 and the rest of the bits are the port number to
  6532. which a node is connected. Since the LSB is always 1, the minimum and
  6533. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  6534. reserved and is assigned to the control processor in a SONET switch.
  6535.  
  6536. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  6537. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  6538. indicate the group address.
  6539.  
  6540. +-------------+-+
  6541. | | | | | | | | |
  6542. | |port number|1|
  6543. +-+-----------+-+
  6544. ^ ^
  6545. | |
  6546. | +------- EA bit (always 1)
  6547. |
  6548. 1 : broadcast, multicast
  6549. 0 : unicast
  6550.  
  6551. Figure 1 Address format
  6552.  
  6553. 2.2 Address in multi-switch environment
  6554.  
  6555. In a multi-switch environment, variable-length subnet addressing is
  6556. used. Each switch has a switch number that is unique within the
  6557. system. Subnetted node addresses consist of the switch number and the
  6558. port number to which a node is connected. The address format is "0
  6559. <switch number> <node number> 1" for a unicast address, "all 1" for
  6560. the broadcast address, and "1 <group address> 1" for a multicast
  6561. address.
  6562.  
  6563. The address 0x01 is reserved and is assigned to the control processor
  6564. in the "local" switch. That is, it indicates the switch itself to
  6565. which the node is connected. The addresses of the form "0 <switch
  6566. number> <all 0> 1" are reserved, and indicates the control processor
  6567. of the switch designated by the switch number.
  6568.  
  6569. In Figure 2, the switch numbers are two bits long. Node N1 is
  6570. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  6571.  
  6572.  
  6573.  
  6574. Murakami & Maruyama Informational [Page 2]
  6576. RFC 2173 MAPOS June 1997
  6577.  
  6578.  
  6579. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  6580. has an address 01001001(0x49), since the switch number of S2 is 0x2
  6581. (10 in binary) and the port number is 0x09. Note that all the port
  6582. numbers are odd because the LSBs are always 1.
  6583.  
  6584. +------+
  6585. | node |
  6586. | N1 |
  6587. +------+
  6588. | 00100011(0x23)
  6589. |
  6590. |0x3 |0x3
  6591. +------+ +---+----+ +---+----+ +------+
  6592. | node +----+ SONET +-------+ SONET +-----+ node |
  6593. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  6594. +------+ | S1 | | S2 | +------+
  6595. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  6596. +---+----+ +---+----+
  6597. |0x7 |0x7
  6598.  
  6599.  
  6600. Figure 2 Addressing in Multiple Switch Environment
  6601.  
  6602. 4 NSP(Node-Switch Protocol)
  6603.  
  6604. This section describes the NSP protocol used for automatic node
  6605. address assignment.
  6606.  
  6607. 4.1 NSP protocol
  6608.  
  6609. NSP is introduced to provide an automatic node address assignment
  6610. function in MAPOS version 1. It reduces the administrative overhead
  6611. of node address configuration for each node and prevents troubles
  6612. such as address inconsistency and collision. When a node is connected
  6613. to a switch and receives SONET signal correctly, the node sends an
  6614. address request packet to the control processor in the local switch.
  6615. The destination address of this packet is 00000001(0x01). When the
  6616. control processor receives the packet, it replies with an address
  6617. assignment packet. The destination is the assigned node address. If
  6618. the node does not receive the address assignment packet within 5
  6619. seconds, it retransmits the address request packet. The
  6620. retransmission continues until the node successfully receives the
  6621. address assignment packet.
  6622.  
  6623. Whenever a node detects a transmission error such as carrier loss or
  6624. out-of-synchronization, it SHOULD send an address request packet to
  6625. the control processor and verify its current address. In addition, a
  6626. node MUST verify its address by sending address request packets every
  6627.  
  6628.  
  6629.  
  6630. Murakami & Maruyama Informational [Page 3]
  6632. RFC 2173 MAPOS June 1997
  6633.  
  6634.  
  6635. 30 seconds. The switch regards them as keep-alive packets and
  6636. utilizes them to detect the node's status. If it has not received a
  6637. request packet for more than 90 seconds, it assumes that the node
  6638. went down. In addition, it also assumes the node went down when a
  6639. switch detects a SONET signal failure.
  6640.  
  6641. 4.2 Packet Format
  6642.  
  6643. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  6644. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  6645. information field contains the NSP packet as shown in Figure 3.
  6646.  
  6647.  
  6648. +-----------+------------+
  6649. I command I address I
  6650. +-----------+------------+
  6651. I<- 32bit ->I<- 32 bit ->I
  6652.  
  6653. Figure 3 NSP packet format
  6654.  
  6655. The command field is 32 bits long and has the following values (in
  6656. decimal);
  6657.  
  6658. 1 address request
  6659. 2 address assignment
  6660. 3 reject(error)
  6661.  
  6662. The length of the address field is 32bits. In address request
  6663. packets, the NSP address field SHOULD be filled with zeroes, although
  6664. the switch ignores it. In address assignment packets, the assigned
  6665. address is placed in the least significant byte of the field. The
  6666. rest of the field is padded with zeroes. When the switch can not
  6667. assign the address for some reason, the switch replies with a reject
  6668. command (the values is 3). The value of the address field is
  6669. undefined.
  6670.  
  6671. 4.3 Consideration for special cases
  6672.  
  6673. There are two special cases to consider. One is a point-to-point
  6674. connection without a switch. The other is loop-back, that is, direct
  6675. connection between the input and the output of the same port.
  6676.  
  6677. 4.3.1 point-to-point
  6678.  
  6679. In the case of a point-to-point connection shown in Figure 4, a node
  6680. sends an address request packet to the other node. The destination
  6681. address is 00000001(0x01), that is usually a control processor in a
  6682. switch. When a node receives the address request, it detects the
  6683.  
  6684.  
  6685.  
  6686. Murakami & Maruyama Informational [Page 4]
  6688. RFC 2173 MAPOS June 1997
  6689.  
  6690.  
  6691. point-to-point connection by examining both the destination address
  6692. and the command contained. Then, it MUST reply with an address
  6693. assignment packet. The assigned address MUST be 00000011(0x03). Since
  6694. both nodes send an address request to each other, both of them get
  6695. address 00000011(0x03). Since any address can be used in point-to-
  6696. point environment, there is no problem even if both of the nodes have
  6697. the same address.
  6698.  
  6699. ---- address request ----> 0x01
  6700. 0x03 <---- address assignment ----
  6701. +------+ +------+
  6702. | node +--------------------------------+ node |
  6703. +------+ +------+
  6704. 0x01 <---- address request ----
  6705. ---- address assignment ----> 0x03
  6706.  
  6707. Figure 4 Point-to-point connection
  6708.  
  6709. 4.3.2 loop-back
  6710.  
  6711. Another special case is loop-back where the output port of a node is
  6712. simply connected to its input port as shown in Figure 5. In this
  6713. case, the same mechanism as that for point-to-point can be applied
  6714. without modification. A node sends an address request packet
  6715. destined to 00000001(0x01). The node then receives the same packet.
  6716. Since the destination is 00000001(0x01), it replies with an address
  6717. assignment packet, containing the assigned address 00000011(0x03), to
  6718. the address 0000 0011(0x03). Thus, the node obtains the address
  6719. 00000011(0x03).
  6720.  
  6721. ---- address request ----> 0x01
  6722. +------+ --- address assignment --> 0x03
  6723. | +-------------->-----------------+
  6724. | node + |
  6725. | +--------------<-----------------+
  6726. +------+
  6727.  
  6728. Figure 5 Loop-back Configuration
  6729.  
  6730.  
  6731.  
  6732.  
  6733.  
  6734.  
  6735.  
  6736.  
  6737.  
  6738.  
  6739.  
  6740.  
  6741.  
  6742. Murakami & Maruyama Informational [Page 5]
  6744. RFC 2173 MAPOS June 1997
  6745.  
  6746.  
  6747. 5. Security Considerations
  6748.  
  6749. Security issues are not discussed in this memo.
  6750.  
  6751. References
  6752.  
  6753. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  6754. over SONET/SDH, Version 1," RFC-2171, June 1997.
  6755.  
  6756. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  6757. Rates (1990).
  6758.  
  6759. [3] CCITT Recommendation G.708: Network Node Interface for
  6760. Synchronous Digital Hierarchy (1990).
  6761.  
  6762. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  6763. (1990).
  6764.  
  6765. [5] American National Standard for Telecommunications - Digital
  6766. Hierarchy - Optical Interface Rates and Formats Specification,
  6767. ANSI T1.105-1991.
  6768.  
  6769. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  6770. Numbers," RFC-2172, June, 1997.
  6771.  
  6772. Acknowledgements
  6773.  
  6774. The authors would like to acknowledge the contributions and
  6775. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  6776. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  6777.  
  6778. Authors' Address
  6779.  
  6780. Ken Murakami
  6781. NTT Software Laboratories
  6782. 3-9-11, Midori-cho
  6783. Musashino-shi
  6784. Tokyo 180, Japan
  6785. E-mail: murakami@ntt-20.ecl.net
  6786.  
  6787. Mitsuru Maruyama
  6788. NTT Software Laboratories
  6789. 3-9-11, Midori-cho
  6790. Musashino-shi
  6791. Tokyo 180, Japan
  6792. E-mail: mitsuru@ntt-20.ecl.net
  6793.  
  6794.  
  6795.  
  6796.  
  6797.  
  6798. Murakami & Maruyama Informational [Page 6]
  6800.  
  6801.  
  6802.  
  6803.  
  6804.  
  6805.  
  6806.  
  6807.  
  6808.  
  6809. Network Working Group K. Murakami
  6810. Request for Comments: 2173 M. Maruyama
  6811. Category: Informational NTT Laboratories
  6812. June 1997
  6813.  
  6814.  
  6815. A MAPOS version 1 Extension - Node Switch Protocol
  6816.  
  6817. Status of this Memo
  6818.  
  6819. This memo provides information for the Internet community. This memo
  6820. does not specify an Internet standard of any kind. Distribution of
  6821. this memo is unlimited.
  6822.  
  6823. Abstract
  6824.  
  6825. This document describes a MAPOS extension, Node Switch Protocol, for
  6826. automatic node address assignment. MAPOS is a multiple access
  6827. protocol for transmission of network-protocol datagrams, encapsulated
  6828. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  6829. automates the HDLC address configuration of each node. Using NSP, a
  6830. node retrieves its HDLC address from the switch to which it is
  6831. connected.
  6832.  
  6833. 1. Introduction
  6834.  
  6835. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  6836. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  6837. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  6838. switch provides multiple access capability to each node. In MAPOS,
  6839. each node has a unique HDLC address within a switch. The address is
  6840. equivalent to the port number of the switch to which the node is
  6841. connected. This document describes an extension to MAPOS, Node
  6842. Switch Protocol, which enable automatic HDLC address assignment.
  6843. First, it explains the addressing of MAPOS. Then, it describes the
  6844. NSP protocol for automatic HDLC node address assignment.
  6845.  
  6846. 2. Node Address Format
  6847.  
  6848. This section describes MAPOS Version 1 address format in single and
  6849. multiple switch environment.
  6850.  
  6851.  
  6852.  
  6853.  
  6854.  
  6855.  
  6856.  
  6857.  
  6858.  
  6859.  
  6860. Murakami & Maruyama Informational [Page 1]
  6862. RFC 2173 MAPOS June 1997
  6863.  
  6864.  
  6865. 2.1 Address Format
  6866.  
  6867. In MAPOS network, each end node has a unique HDLC address. As shown
  6868. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  6869. indicates the end of the field. When a SONET switch receives an HDLC
  6870. frame, it forwards the frame based on the address in the frame
  6871. header.
  6872.  
  6873. In unicast, MSB is 0 and the rest of the bits are the port number to
  6874. which a node is connected. Since the LSB is always 1, the minimum and
  6875. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  6876. reserved and is assigned to the control processor in a SONET switch.
  6877.  
  6878. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  6879. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  6880. indicate the group address.
  6881.  
  6882. +-------------+-+
  6883. | | | | | | | | |
  6884. | |port number|1|
  6885. +-+-----------+-+
  6886. ^ ^
  6887. | |
  6888. | +------- EA bit (always 1)
  6889. |
  6890. 1 : broadcast, multicast
  6891. 0 : unicast
  6892.  
  6893. Figure 1 Address format
  6894.  
  6895. 2.2 Address in multi-switch environment
  6896.  
  6897. In a multi-switch environment, variable-length subnet addressing is
  6898. used. Each switch has a switch number that is unique within the
  6899. system. Subnetted node addresses consist of the switch number and the
  6900. port number to which a node is connected. The address format is "0
  6901. <switch number> <node number> 1" for a unicast address, "all 1" for
  6902. the broadcast address, and "1 <group address> 1" for a multicast
  6903. address.
  6904.  
  6905. The address 0x01 is reserved and is assigned to the control processor
  6906. in the "local" switch. That is, it indicates the switch itself to
  6907. which the node is connected. The addresses of the form "0 <switch
  6908. number> <all 0> 1" are reserved, and indicates the control processor
  6909. of the switch designated by the switch number.
  6910.  
  6911. In Figure 2, the switch numbers are two bits long. Node N1 is
  6912. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  6913.  
  6914.  
  6915.  
  6916. Murakami & Maruyama Informational [Page 2]
  6918. RFC 2173 MAPOS June 1997
  6919.  
  6920.  
  6921. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  6922. has an address 01001001(0x49), since the switch number of S2 is 0x2
  6923. (10 in binary) and the port number is 0x09. Note that all the port
  6924. numbers are odd because the LSBs are always 1.
  6925.  
  6926. +------+
  6927. | node |
  6928. | N1 |
  6929. +------+
  6930. | 00100011(0x23)
  6931. |
  6932. |0x3 |0x3
  6933. +------+ +---+----+ +---+----+ +------+
  6934. | node +----+ SONET +-------+ SONET +-----+ node |
  6935. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  6936. +------+ | S1 | | S2 | +------+
  6937. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  6938. +---+----+ +---+----+
  6939. |0x7 |0x7
  6940.  
  6941.  
  6942. Figure 2 Addressing in Multiple Switch Environment
  6943.  
  6944. 4 NSP(Node-Switch Protocol)
  6945.  
  6946. This section describes the NSP protocol used for automatic node
  6947. address assignment.
  6948.  
  6949. 4.1 NSP protocol
  6950.  
  6951. NSP is introduced to provide an automatic node address assignment
  6952. function in MAPOS version 1. It reduces the administrative overhead
  6953. of node address configuration for each node and prevents troubles
  6954. such as address inconsistency and collision. When a node is connected
  6955. to a switch and receives SONET signal correctly, the node sends an
  6956. address request packet to the control processor in the local switch.
  6957. The destination address of this packet is 00000001(0x01). When the
  6958. control processor receives the packet, it replies with an address
  6959. assignment packet. The destination is the assigned node address. If
  6960. the node does not receive the address assignment packet within 5
  6961. seconds, it retransmits the address request packet. The
  6962. retransmission continues until the node successfully receives the
  6963. address assignment packet.
  6964.  
  6965. Whenever a node detects a transmission error such as carrier loss or
  6966. out-of-synchronization, it SHOULD send an address request packet to
  6967. the control processor and verify its current address. In addition, a
  6968. node MUST verify its address by sending address request packets every
  6969.  
  6970.  
  6971.  
  6972. Murakami & Maruyama Informational [Page 3]
  6974. RFC 2173 MAPOS June 1997
  6975.  
  6976.  
  6977. 30 seconds. The switch regards them as keep-alive packets and
  6978. utilizes them to detect the node's status. If it has not received a
  6979. request packet for more than 90 seconds, it assumes that the node
  6980. went down. In addition, it also assumes the node went down when a
  6981. switch detects a SONET signal failure.
  6982.  
  6983. 4.2 Packet Format
  6984.  
  6985. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  6986. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  6987. information field contains the NSP packet as shown in Figure 3.
  6988.  
  6989.  
  6990. +-----------+------------+
  6991. I command I address I
  6992. +-----------+------------+
  6993. I<- 32bit ->I<- 32 bit ->I
  6994.  
  6995. Figure 3 NSP packet format
  6996.  
  6997. The command field is 32 bits long and has the following values (in
  6998. decimal);
  6999.  
  7000. 1 address request
  7001. 2 address assignment
  7002. 3 reject(error)
  7003.  
  7004. The length of the address field is 32bits. In address request
  7005. packets, the NSP address field SHOULD be filled with zeroes, although
  7006. the switch ignores it. In address assignment packets, the assigned
  7007. address is placed in the least significant byte of the field. The
  7008. rest of the field is padded with zeroes. When the switch can not
  7009. assign the address for some reason, the switch replies with a reject
  7010. command (the values is 3). The value of the address field is
  7011. undefined.
  7012.  
  7013. 4.3 Consideration for special cases
  7014.  
  7015. There are two special cases to consider. One is a point-to-point
  7016. connection without a switch. The other is loop-back, that is, direct
  7017. connection between the input and the output of the same port.
  7018.  
  7019. 4.3.1 point-to-point
  7020.  
  7021. In the case of a point-to-point connection shown in Figure 4, a node
  7022. sends an address request packet to the other node. The destination
  7023. address is 00000001(0x01), that is usually a control processor in a
  7024. switch. When a node receives the address request, it detects the
  7025.  
  7026.  
  7027.  
  7028. Murakami & Maruyama Informational [Page 4]
  7030. RFC 2173 MAPOS June 1997
  7031.  
  7032.  
  7033. point-to-point connection by examining both the destination address
  7034. and the command contained. Then, it MUST reply with an address
  7035. assignment packet. The assigned address MUST be 00000011(0x03). Since
  7036. both nodes send an address request to each other, both of them get
  7037. address 00000011(0x03). Since any address can be used in point-to-
  7038. point environment, there is no problem even if both of the nodes have
  7039. the same address.
  7040.  
  7041. ---- address request ----> 0x01
  7042. 0x03 <---- address assignment ----
  7043. +------+ +------+
  7044. | node +--------------------------------+ node |
  7045. +------+ +------+
  7046. 0x01 <---- address request ----
  7047. ---- address assignment ----> 0x03
  7048.  
  7049. Figure 4 Point-to-point connection
  7050.  
  7051. 4.3.2 loop-back
  7052.  
  7053. Another special case is loop-back where the output port of a node is
  7054. simply connected to its input port as shown in Figure 5. In this
  7055. case, the same mechanism as that for point-to-point can be applied
  7056. without modification. A node sends an address request packet
  7057. destined to 00000001(0x01). The node then receives the same packet.
  7058. Since the destination is 00000001(0x01), it replies with an address
  7059. assignment packet, containing the assigned address 00000011(0x03), to
  7060. the address 0000 0011(0x03). Thus, the node obtains the address
  7061. 00000011(0x03).
  7062.  
  7063. ---- address request ----> 0x01
  7064. +------+ --- address assignment --> 0x03
  7065. | +-------------->-----------------+
  7066. | node + |
  7067. | +--------------<-----------------+
  7068. +------+
  7069.  
  7070. Figure 5 Loop-back Configuration
  7071.  
  7072.  
  7073.  
  7074.  
  7075.  
  7076.  
  7077.  
  7078.  
  7079.  
  7080.  
  7081.  
  7082.  
  7083.  
  7084. Murakami & Maruyama Informational [Page 5]
  7086. RFC 2173 MAPOS June 1997
  7087.  
  7088.  
  7089. 5. Security Considerations
  7090.  
  7091. Security issues are not discussed in this memo.
  7092.  
  7093. References
  7094.  
  7095. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  7096. over SONET/SDH, Version 1," RFC-2171, June 1997.
  7097.  
  7098. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  7099. Rates (1990).
  7100.  
  7101. [3] CCITT Recommendation G.708: Network Node Interface for
  7102. Synchronous Digital Hierarchy (1990).
  7103.  
  7104. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  7105. (1990).
  7106.  
  7107. [5] American National Standard for Telecommunications - Digital
  7108. Hierarchy - Optical Interface Rates and Formats Specification,
  7109. ANSI T1.105-1991.
  7110.  
  7111. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  7112. Numbers," RFC-2172, June, 1997.
  7113.  
  7114. Acknowledgements
  7115.  
  7116. The authors would like to acknowledge the contributions and
  7117. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  7118. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  7119.  
  7120. Authors' Address
  7121.  
  7122. Ken Murakami
  7123. NTT Software Laboratories
  7124. 3-9-11, Midori-cho
  7125. Musashino-shi
  7126. Tokyo 180, Japan
  7127. E-mail: murakami@ntt-20.ecl.net
  7128.  
  7129. Mitsuru Maruyama
  7130. NTT Software Laboratories
  7131. 3-9-11, Midori-cho
  7132. Musashino-shi
  7133. Tokyo 180, Japan
  7134. E-mail: mitsuru@ntt-20.ecl.net
  7135.  
  7136.  
  7137.  
  7138.  
  7139.  
  7140. Murakami & Maruyama Informational [Page 6]
  7141.  
  7142.  
  7143.  
  7144.  
  7145.  
  7146.  
  7147.  
  7148. Network Working Group K. Murakami
  7149. Request for Comments: 2173 M. Maruyama
  7150. Category: Informational NTT Laboratories
  7151. June 1997
  7152.  
  7153.  
  7154. A MAPOS version 1 Extension - Node Switch Protocol
  7155.  
  7156. Status of this Memo
  7157.  
  7158. This memo provides information for the Internet community. This memo
  7159. does not specify an Internet standard of any kind. Distribution of
  7160. this memo is unlimited.
  7161.  
  7162. Abstract
  7163.  
  7164. This document describes a MAPOS extension, Node Switch Protocol, for
  7165. automatic node address assignment. MAPOS is a multiple access
  7166. protocol for transmission of network-protocol datagrams, encapsulated
  7167. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  7168. automates the HDLC address configuration of each node. Using NSP, a
  7169. node retrieves its HDLC address from the switch to which it is
  7170. connected.
  7171.  
  7172. 1. Introduction
  7173.  
  7174. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  7175. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  7176. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  7177. switch provides multiple access capability to each node. In MAPOS,
  7178. each node has a unique HDLC address within a switch. The address is
  7179. equivalent to the port number of the switch to which the node is
  7180. connected. This document describes an extension to MAPOS, Node
  7181. Switch Protocol, which enable automatic HDLC address assignment.
  7182. First, it explains the addressing of MAPOS. Then, it describes the
  7183. NSP protocol for automatic HDLC node address assignment.
  7184.  
  7185. 2. Node Address Format
  7186.  
  7187. This section describes MAPOS Version 1 address format in single and
  7188. multiple switch environment.
  7189.  
  7190.  
  7191.  
  7192.  
  7193.  
  7194.  
  7195.  
  7196.  
  7197.  
  7198.  
  7199. Murakami & Maruyama Informational [Page 1]
  7201. RFC 2173 MAPOS June 1997
  7202.  
  7203.  
  7204. 2.1 Address Format
  7205.  
  7206. In MAPOS network, each end node has a unique HDLC address. As shown
  7207. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  7208. indicates the end of the field. When a SONET switch receives an HDLC
  7209. frame, it forwards the frame based on the address in the frame
  7210. header.
  7211.  
  7212. In unicast, MSB is 0 and the rest of the bits are the port number to
  7213. which a node is connected. Since the LSB is always 1, the minimum and
  7214. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  7215. reserved and is assigned to the control processor in a SONET switch.
  7216.  
  7217. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  7218. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  7219. indicate the group address.
  7220.  
  7221. +-------------+-+
  7222. | | | | | | | | |
  7223. | |port number|1|
  7224. +-+-----------+-+
  7225. ^ ^
  7226. | |
  7227. | +------- EA bit (always 1)
  7228. |
  7229. 1 : broadcast, multicast
  7230. 0 : unicast
  7231.  
  7232. Figure 1 Address format
  7233.  
  7234. 2.2 Address in multi-switch environment
  7235.  
  7236. In a multi-switch environment, variable-length subnet addressing is
  7237. used. Each switch has a switch number that is unique within the
  7238. system. Subnetted node addresses consist of the switch number and the
  7239. port number to which a node is connected. The address format is "0
  7240. <switch number> <node number> 1" for a unicast address, "all 1" for
  7241. the broadcast address, and "1 <group address> 1" for a multicast
  7242. address.
  7243.  
  7244. The address 0x01 is reserved and is assigned to the control processor
  7245. in the "local" switch. That is, it indicates the switch itself to
  7246. which the node is connected. The addresses of the form "0 <switch
  7247. number> <all 0> 1" are reserved, and indicates the control processor
  7248. of the switch designated by the switch number.
  7249.  
  7250. In Figure 2, the switch numbers are two bits long. Node N1 is
  7251. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  7252.  
  7253.  
  7254.  
  7255. Murakami & Maruyama Informational [Page 2]
  7257. RFC 2173 MAPOS June 1997
  7258.  
  7259.  
  7260. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  7261. has an address 01001001(0x49), since the switch number of S2 is 0x2
  7262. (10 in binary) and the port number is 0x09. Note that all the port
  7263. numbers are odd because the LSBs are always 1.
  7264.  
  7265. +------+
  7266. | node |
  7267. | N1 |
  7268. +------+
  7269. | 00100011(0x23)
  7270. |
  7271. |0x3 |0x3
  7272. +------+ +---+----+ +---+----+ +------+
  7273. | node +----+ SONET +-------+ SONET +-----+ node |
  7274. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  7275. +------+ | S1 | | S2 | +------+
  7276. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  7277. +---+----+ +---+----+
  7278. |0x7 |0x7
  7279.  
  7280.  
  7281. Figure 2 Addressing in Multiple Switch Environment
  7282.  
  7283. 4 NSP(Node-Switch Protocol)
  7284.  
  7285. This section describes the NSP protocol used for automatic node
  7286. address assignment.
  7287.  
  7288. 4.1 NSP protocol
  7289.  
  7290. NSP is introduced to provide an automatic node address assignment
  7291. function in MAPOS version 1. It reduces the administrative overhead
  7292. of node address configuration for each node and prevents troubles
  7293. such as address inconsistency and collision. When a node is connected
  7294. to a switch and receives SONET signal correctly, the node sends an
  7295. address request packet to the control processor in the local switch.
  7296. The destination address of this packet is 00000001(0x01). When the
  7297. control processor receives the packet, it replies with an address
  7298. assignment packet. The destination is the assigned node address. If
  7299. the node does not receive the address assignment packet within 5
  7300. seconds, it retransmits the address request packet. The
  7301. retransmission continues until the node successfully receives the
  7302. address assignment packet.
  7303.  
  7304. Whenever a node detects a transmission error such as carrier loss or
  7305. out-of-synchronization, it SHOULD send an address request packet to
  7306. the control processor and verify its current address. In addition, a
  7307. node MUST verify its address by sending address request packets every
  7308.  
  7309.  
  7310.  
  7311. Murakami & Maruyama Informational [Page 3]
  7313. RFC 2173 MAPOS June 1997
  7314.  
  7315.  
  7316. 30 seconds. The switch regards them as keep-alive packets and
  7317. utilizes them to detect the node's status. If it has not received a
  7318. request packet for more than 90 seconds, it assumes that the node
  7319. went down. In addition, it also assumes the node went down when a
  7320. switch detects a SONET signal failure.
  7321.  
  7322. 4.2 Packet Format
  7323.  
  7324. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  7325. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  7326. information field contains the NSP packet as shown in Figure 3.
  7327.  
  7328.  
  7329. +-----------+------------+
  7330. I command I address I
  7331. +-----------+------------+
  7332. I<- 32bit ->I<- 32 bit ->I
  7333.  
  7334. Figure 3 NSP packet format
  7335.  
  7336. The command field is 32 bits long and has the following values (in
  7337. decimal);
  7338.  
  7339. 1 address request
  7340. 2 address assignment
  7341. 3 reject(error)
  7342.  
  7343. The length of the address field is 32bits. In address request
  7344. packets, the NSP address field SHOULD be filled with zeroes, although
  7345. the switch ignores it. In address assignment packets, the assigned
  7346. address is placed in the least significant byte of the field. The
  7347. rest of the field is padded with zeroes. When the switch can not
  7348. assign the address for some reason, the switch replies with a reject
  7349. command (the values is 3). The value of the address field is
  7350. undefined.
  7351.  
  7352. 4.3 Consideration for special cases
  7353.  
  7354. There are two special cases to consider. One is a point-to-point
  7355. connection without a switch. The other is loop-back, that is, direct
  7356. connection between the input and the output of the same port.
  7357.  
  7358. 4.3.1 point-to-point
  7359.  
  7360. In the case of a point-to-point connection shown in Figure 4, a node
  7361. sends an address request packet to the other node. The destination
  7362. address is 00000001(0x01), that is usually a control processor in a
  7363. switch. When a node receives the address request, it detects the
  7364.  
  7365.  
  7366.  
  7367. Murakami & Maruyama Informational [Page 4]
  7369. RFC 2173 MAPOS June 1997
  7370.  
  7371.  
  7372. point-to-point connection by examining both the destination address
  7373. and the command contained. Then, it MUST reply with an address
  7374. assignment packet. The assigned address MUST be 00000011(0x03). Since
  7375. both nodes send an address request to each other, both of them get
  7376. address 00000011(0x03). Since any address can be used in point-to-
  7377. point environment, there is no problem even if both of the nodes have
  7378. the same address.
  7379.  
  7380. ---- address request ----> 0x01
  7381. 0x03 <---- address assignment ----
  7382. +------+ +------+
  7383. | node +--------------------------------+ node |
  7384. +------+ +------+
  7385. 0x01 <---- address request ----
  7386. ---- address assignment ----> 0x03
  7387.  
  7388. Figure 4 Point-to-point connection
  7389.  
  7390. 4.3.2 loop-back
  7391.  
  7392. Another special case is loop-back where the output port of a node is
  7393. simply connected to its input port as shown in Figure 5. In this
  7394. case, the same mechanism as that for point-to-point can be applied
  7395. without modification. A node sends an address request packet
  7396. destined to 00000001(0x01). The node then receives the same packet.
  7397. Since the destination is 00000001(0x01), it replies with an address
  7398. assignment packet, containing the assigned address 00000011(0x03), to
  7399. the address 0000 0011(0x03). Thus, the node obtains the address
  7400. 00000011(0x03).
  7401.  
  7402. ---- address request ----> 0x01
  7403. +------+ --- address assignment --> 0x03
  7404. | +-------------->-----------------+
  7405. | node + |
  7406. | +--------------<-----------------+
  7407. +------+
  7408.  
  7409. Figure 5 Loop-back Configuration
  7410.  
  7411.  
  7412.  
  7413.  
  7414.  
  7415.  
  7416.  
  7417.  
  7418.  
  7419.  
  7420.  
  7421.  
  7422.  
  7423. Murakami & Maruyama Informational [Page 5]
  7425. RFC 2173 MAPOS June 1997
  7426.  
  7427.  
  7428. 5. Security Considerations
  7429.  
  7430. Security issues are not discussed in this memo.
  7431.  
  7432. References
  7433.  
  7434. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  7435. over SONET/SDH, Version 1," RFC-2171, June 1997.
  7436.  
  7437. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  7438. Rates (1990).
  7439.  
  7440. [3] CCITT Recommendation G.708: Network Node Interface for
  7441. Synchronous Digital Hierarchy (1990).
  7442.  
  7443. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  7444. (1990).
  7445.  
  7446. [5] American National Standard for Telecommunications - Digital
  7447. Hierarchy - Optical Interface Rates and Formats Specification,
  7448. ANSI T1.105-1991.
  7449.  
  7450. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  7451. Numbers," RFC-2172, June, 1997.
  7452.  
  7453. Acknowledgements
  7454.  
  7455. The authors would like to acknowledge the contributions and
  7456. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  7457. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  7458.  
  7459. Authors' Address
  7460.  
  7461. Ken Murakami
  7462. NTT Software Laboratories
  7463. 3-9-11, Midori-cho
  7464. Musashino-shi
  7465. Tokyo 180, Japan
  7466. E-mail: murakami@ntt-20.ecl.net
  7467.  
  7468. Mitsuru Maruyama
  7469. NTT Software Laboratories
  7470. 3-9-11, Midori-cho
  7471. Musashino-shi
  7472. Tokyo 180, Japan
  7473. E-mail: mitsuru@ntt-20.ecl.net
  7474.  
  7475.  
  7476.  
  7477.  
  7478.  
  7479. Murakami & Maruyama Informational [Page 6]
  7481.  
  7482.  
  7483.  
  7484.  
  7485.  
  7486.  
  7487.  
  7488. Network Working Group K. Murakami
  7489. Request for Comments: 2173 M. Maruyama
  7490. Category: Informational NTT Laboratories
  7491. June 1997
  7492.  
  7493.  
  7494. A MAPOS version 1 Extension - Node Switch Protocol
  7495.  
  7496. Status of this Memo
  7497.  
  7498. This memo provides information for the Internet community. This memo
  7499. does not specify an Internet standard of any kind. Distribution of
  7500. this memo is unlimited.
  7501.  
  7502. Abstract
  7503.  
  7504. This document describes a MAPOS extension, Node Switch Protocol, for
  7505. automatic node address assignment. MAPOS is a multiple access
  7506. protocol for transmission of network-protocol datagrams, encapsulated
  7507. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  7508. automates the HDLC address configuration of each node. Using NSP, a
  7509. node retrieves its HDLC address from the switch to which it is
  7510. connected.
  7511.  
  7512. 1. Introduction
  7513.  
  7514. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  7515. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  7516. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  7517. switch provides multiple access capability to each node. In MAPOS,
  7518. each node has a unique HDLC address within a switch. The address is
  7519. equivalent to the port number of the switch to which the node is
  7520. connected. This document describes an extension to MAPOS, Node
  7521. Switch Protocol, which enable automatic HDLC address assignment.
  7522. First, it explains the addressing of MAPOS. Then, it describes the
  7523. NSP protocol for automatic HDLC node address assignment.
  7524.  
  7525. 2. Node Address Format
  7526.  
  7527. This section describes MAPOS Version 1 address format in single and
  7528. multiple switch environment.
  7529.  
  7530.  
  7531.  
  7532.  
  7533.  
  7534.  
  7535.  
  7536.  
  7537.  
  7538.  
  7539. Murakami & Maruyama Informational [Page 1]
  7541. RFC 2173 MAPOS June 1997
  7542.  
  7543.  
  7544. 2.1 Address Format
  7545.  
  7546. In MAPOS network, each end node has a unique HDLC address. As shown
  7547. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  7548. indicates the end of the field. When a SONET switch receives an HDLC
  7549. frame, it forwards the frame based on the address in the frame
  7550. header.
  7551.  
  7552. In unicast, MSB is 0 and the rest of the bits are the port number to
  7553. which a node is connected. Since the LSB is always 1, the minimum and
  7554. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  7555. reserved and is assigned to the control processor in a SONET switch.
  7556.  
  7557. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  7558. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  7559. indicate the group address.
  7560.  
  7561. +-------------+-+
  7562. | | | | | | | | |
  7563. | |port number|1|
  7564. +-+-----------+-+
  7565. ^ ^
  7566. | |
  7567. | +------- EA bit (always 1)
  7568. |
  7569. 1 : broadcast, multicast
  7570. 0 : unicast
  7571.  
  7572. Figure 1 Address format
  7573.  
  7574. 2.2 Address in multi-switch environment
  7575.  
  7576. In a multi-switch environment, variable-length subnet addressing is
  7577. used. Each switch has a switch number that is unique within the
  7578. system. Subnetted node addresses consist of the switch number and the
  7579. port number to which a node is connected. The address format is "0
  7580. <switch number> <node number> 1" for a unicast address, "all 1" for
  7581. the broadcast address, and "1 <group address> 1" for a multicast
  7582. address.
  7583.  
  7584. The address 0x01 is reserved and is assigned to the control processor
  7585. in the "local" switch. That is, it indicates the switch itself to
  7586. which the node is connected. The addresses of the form "0 <switch
  7587. number> <all 0> 1" are reserved, and indicates the control processor
  7588. of the switch designated by the switch number.
  7589.  
  7590. In Figure 2, the switch numbers are two bits long. Node N1 is
  7591. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  7592.  
  7593.  
  7594.  
  7595. Murakami & Maruyama Informational [Page 2]
  7597. RFC 2173 MAPOS June 1997
  7598.  
  7599.  
  7600. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  7601. has an address 01001001(0x49), since the switch number of S2 is 0x2
  7602. (10 in binary) and the port number is 0x09. Note that all the port
  7603. numbers are odd because the LSBs are always 1.
  7604.  
  7605. +------+
  7606. | node |
  7607. | N1 |
  7608. +------+
  7609. | 00100011(0x23)
  7610. |
  7611. |0x3 |0x3
  7612. +------+ +---+----+ +---+----+ +------+
  7613. | node +----+ SONET +-------+ SONET +-----+ node |
  7614. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  7615. +------+ | S1 | | S2 | +------+
  7616. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  7617. +---+----+ +---+----+
  7618. |0x7 |0x7
  7619.  
  7620.  
  7621. Figure 2 Addressing in Multiple Switch Environment
  7622.  
  7623. 4 NSP(Node-Switch Protocol)
  7624.  
  7625. This section describes the NSP protocol used for automatic node
  7626. address assignment.
  7627.  
  7628. 4.1 NSP protocol
  7629.  
  7630. NSP is introduced to provide an automatic node address assignment
  7631. function in MAPOS version 1. It reduces the administrative overhead
  7632. of node address configuration for each node and prevents troubles
  7633. such as address inconsistency and collision. When a node is connected
  7634. to a switch and receives SONET signal correctly, the node sends an
  7635. address request packet to the control processor in the local switch.
  7636. The destination address of this packet is 00000001(0x01). When the
  7637. control processor receives the packet, it replies with an address
  7638. assignment packet. The destination is the assigned node address. If
  7639. the node does not receive the address assignment packet within 5
  7640. seconds, it retransmits the address request packet. The
  7641. retransmission continues until the node successfully receives the
  7642. address assignment packet.
  7643.  
  7644. Whenever a node detects a transmission error such as carrier loss or
  7645. out-of-synchronization, it SHOULD send an address request packet to
  7646. the control processor and verify its current address. In addition, a
  7647. node MUST verify its address by sending address request packets every
  7648.  
  7649.  
  7650.  
  7651. Murakami & Maruyama Informational [Page 3]
  7653. RFC 2173 MAPOS June 1997
  7654.  
  7655.  
  7656. 30 seconds. The switch regards them as keep-alive packets and
  7657. utilizes them to detect the node's status. If it has not received a
  7658. request packet for more than 90 seconds, it assumes that the node
  7659. went down. In addition, it also assumes the node went down when a
  7660. switch detects a SONET signal failure.
  7661.  
  7662. 4.2 Packet Format
  7663.  
  7664. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  7665. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  7666. information field contains the NSP packet as shown in Figure 3.
  7667.  
  7668.  
  7669. +-----------+------------+
  7670. I command I address I
  7671. +-----------+------------+
  7672. I<- 32bit ->I<- 32 bit ->I
  7673.  
  7674. Figure 3 NSP packet format
  7675.  
  7676. The command field is 32 bits long and has the following values (in
  7677. decimal);
  7678.  
  7679. 1 address request
  7680. 2 address assignment
  7681. 3 reject(error)
  7682.  
  7683. The length of the address field is 32bits. In address request
  7684. packets, the NSP address field SHOULD be filled with zeroes, although
  7685. the switch ignores it. In address assignment packets, the assigned
  7686. address is placed in the least significant byte of the field. The
  7687. rest of the field is padded with zeroes. When the switch can not
  7688. assign the address for some reason, the switch replies with a reject
  7689. command (the values is 3). The value of the address field is
  7690. undefined.
  7691.  
  7692. 4.3 Consideration for special cases
  7693.  
  7694. There are two special cases to consider. One is a point-to-point
  7695. connection without a switch. The other is loop-back, that is, direct
  7696. connection between the input and the output of the same port.
  7697.  
  7698. 4.3.1 point-to-point
  7699.  
  7700. In the case of a point-to-point connection shown in Figure 4, a node
  7701. sends an address request packet to the other node. The destination
  7702. address is 00000001(0x01), that is usually a control processor in a
  7703. switch. When a node receives the address request, it detects the
  7704.  
  7705.  
  7706.  
  7707. Murakami & Maruyama Informational [Page 4]
  7709. RFC 2173 MAPOS June 1997
  7710.  
  7711.  
  7712. point-to-point connection by examining both the destination address
  7713. and the command contained. Then, it MUST reply with an address
  7714. assignment packet. The assigned address MUST be 00000011(0x03). Since
  7715. both nodes send an address request to each other, both of them get
  7716. address 00000011(0x03). Since any address can be used in point-to-
  7717. point environment, there is no problem even if both of the nodes have
  7718. the same address.
  7719.  
  7720. ---- address request ----> 0x01
  7721. 0x03 <---- address assignment ----
  7722. +------+ +------+
  7723. | node +--------------------------------+ node |
  7724. +------+ +------+
  7725. 0x01 <---- address request ----
  7726. ---- address assignment ----> 0x03
  7727.  
  7728. Figure 4 Point-to-point connection
  7729.  
  7730. 4.3.2 loop-back
  7731.  
  7732. Another special case is loop-back where the output port of a node is
  7733. simply connected to its input port as shown in Figure 5. In this
  7734. case, the same mechanism as that for point-to-point can be applied
  7735. without modification. A node sends an address request packet
  7736. destined to 00000001(0x01). The node then receives the same packet.
  7737. Since the destination is 00000001(0x01), it replies with an address
  7738. assignment packet, containing the assigned address 00000011(0x03), to
  7739. the address 0000 0011(0x03). Thus, the node obtains the address
  7740. 00000011(0x03).
  7741.  
  7742. ---- address request ----> 0x01
  7743. +------+ --- address assignment --> 0x03
  7744. | +-------------->-----------------+
  7745. | node + |
  7746. | +--------------<-----------------+
  7747. +------+
  7748.  
  7749. Figure 5 Loop-back Configuration
  7750.  
  7751.  
  7752.  
  7753.  
  7754.  
  7755.  
  7756.  
  7757.  
  7758.  
  7759.  
  7760.  
  7761.  
  7762.  
  7763. Murakami & Maruyama Informational [Page 5]
  7765. RFC 2173 MAPOS June 1997
  7766.  
  7767.  
  7768. 5. Security Considerations
  7769.  
  7770. Security issues are not discussed in this memo.
  7771.  
  7772. References
  7773.  
  7774. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  7775. over SONET/SDH, Version 1," RFC-2171, June 1997.
  7776.  
  7777. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  7778. Rates (1990).
  7779.  
  7780. [3] CCITT Recommendation G.708: Network Node Interface for
  7781. Synchronous Digital Hierarchy (1990).
  7782.  
  7783. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  7784. (1990).
  7785.  
  7786. [5] American National Standard for Telecommunications - Digital
  7787. Hierarchy - Optical Interface Rates and Formats Specification,
  7788. ANSI T1.105-1991.
  7789.  
  7790. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  7791. Numbers," RFC-2172, June, 1997.
  7792.  
  7793. Acknowledgements
  7794.  
  7795. The authors would like to acknowledge the contributions and
  7796. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  7797. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  7798.  
  7799. Authors' Address
  7800.  
  7801. Ken Murakami
  7802. NTT Software Laboratories
  7803. 3-9-11, Midori-cho
  7804. Musashino-shi
  7805. Tokyo 180, Japan
  7806. E-mail: murakami@ntt-20.ecl.net
  7807.  
  7808. Mitsuru Maruyama
  7809. NTT Software Laboratories
  7810. 3-9-11, Midori-cho
  7811. Musashino-shi
  7812. Tokyo 180, Japan
  7813. E-mail: mitsuru@ntt-20.ecl.net
  7814.  
  7815.  
  7816.  
  7817.  
  7818.  
  7819. Murakami & Maruyama Informational [Page 6]
  7821.  
  7822.  
  7823.  
  7824.  
  7825.  
  7826.  
  7827.  
  7828. Network Working Group K. Murakami
  7829. Request for Comments: 2173 M. Maruyama
  7830. Category: Informational NTT Laboratories
  7831. June 1997
  7832.  
  7833.  
  7834. A MAPOS version 1 Extension - Node Switch Protocol
  7835.  
  7836. Status of this Memo
  7837.  
  7838. This memo provides information for the Internet community. This memo
  7839. does not specify an Internet standard of any kind. Distribution of
  7840. this memo is unlimited.
  7841.  
  7842. Abstract
  7843.  
  7844. This document describes a MAPOS extension, Node Switch Protocol, for
  7845. automatic node address assignment. MAPOS is a multiple access
  7846. protocol for transmission of network-protocol datagrams, encapsulated
  7847. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  7848. automates the HDLC address configuration of each node. Using NSP, a
  7849. node retrieves its HDLC address from the switch to which it is
  7850. connected.
  7851.  
  7852. 1. Introduction
  7853.  
  7854. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  7855. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  7856. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  7857. switch provides multiple access capability to each node. In MAPOS,
  7858. each node has a unique HDLC address within a switch. The address is
  7859. equivalent to the port number of the switch to which the node is
  7860. connected. This document describes an extension to MAPOS, Node
  7861. Switch Protocol, which enable automatic HDLC address assignment.
  7862. First, it explains the addressing of MAPOS. Then, it describes the
  7863. NSP protocol for automatic HDLC node address assignment.
  7864.  
  7865. 2. Node Address Format
  7866.  
  7867. This section describes MAPOS Version 1 address format in single and
  7868. multiple switch environment.
  7869.  
  7870.  
  7871.  
  7872.  
  7873.  
  7874.  
  7875.  
  7876.  
  7877.  
  7878.  
  7879. Murakami & Maruyama Informational [Page 1]
  7881. RFC 2173 MAPOS June 1997
  7882.  
  7883.  
  7884. 2.1 Address Format
  7885.  
  7886. In MAPOS network, each end node has a unique HDLC address. As shown
  7887. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  7888. indicates the end of the field. When a SONET switch receives an HDLC
  7889. frame, it forwards the frame based on the address in the frame
  7890. header.
  7891.  
  7892. In unicast, MSB is 0 and the rest of the bits are the port number to
  7893. which a node is connected. Since the LSB is always 1, the minimum and
  7894. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  7895. reserved and is assigned to the control processor in a SONET switch.
  7896.  
  7897. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  7898. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  7899. indicate the group address.
  7900.  
  7901. +-------------+-+
  7902. | | | | | | | | |
  7903. | |port number|1|
  7904. +-+-----------+-+
  7905. ^ ^
  7906. | |
  7907. | +------- EA bit (always 1)
  7908. |
  7909. 1 : broadcast, multicast
  7910. 0 : unicast
  7911.  
  7912. Figure 1 Address format
  7913.  
  7914. 2.2 Address in multi-switch environment
  7915.  
  7916. In a multi-switch environment, variable-length subnet addressing is
  7917. used. Each switch has a switch number that is unique within the
  7918. system. Subnetted node addresses consist of the switch number and the
  7919. port number to which a node is connected. The address format is "0
  7920. <switch number> <node number> 1" for a unicast address, "all 1" for
  7921. the broadcast address, and "1 <group address> 1" for a multicast
  7922. address.
  7923.  
  7924. The address 0x01 is reserved and is assigned to the control processor
  7925. in the "local" switch. That is, it indicates the switch itself to
  7926. which the node is connected. The addresses of the form "0 <switch
  7927. number> <all 0> 1" are reserved, and indicates the control processor
  7928. of the switch designated by the switch number.
  7929.  
  7930. In Figure 2, the switch numbers are two bits long. Node N1 is
  7931. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  7932.  
  7933.  
  7934.  
  7935. Murakami & Maruyama Informational [Page 2]
  7937. RFC 2173 MAPOS June 1997
  7938.  
  7939.  
  7940. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  7941. has an address 01001001(0x49), since the switch number of S2 is 0x2
  7942. (10 in binary) and the port number is 0x09. Note that all the port
  7943. numbers are odd because the LSBs are always 1.
  7944.  
  7945. +------+
  7946. | node |
  7947. | N1 |
  7948. +------+
  7949. | 00100011(0x23)
  7950. |
  7951. |0x3 |0x3
  7952. +------+ +---+----+ +---+----+ +------+
  7953. | node +----+ SONET +-------+ SONET +-----+ node |
  7954. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  7955. +------+ | S1 | | S2 | +------+
  7956. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  7957. +---+----+ +---+----+
  7958. |0x7 |0x7
  7959.  
  7960.  
  7961. Figure 2 Addressing in Multiple Switch Environment
  7962.  
  7963. 4 NSP(Node-Switch Protocol)
  7964.  
  7965. This section describes the NSP protocol used for automatic node
  7966. address assignment.
  7967.  
  7968. 4.1 NSP protocol
  7969.  
  7970. NSP is introduced to provide an automatic node address assignment
  7971. function in MAPOS version 1. It reduces the administrative overhead
  7972. of node address configuration for each node and prevents troubles
  7973. such as address inconsistency and collision. When a node is connected
  7974. to a switch and receives SONET signal correctly, the node sends an
  7975. address request packet to the control processor in the local switch.
  7976. The destination address of this packet is 00000001(0x01). When the
  7977. control processor receives the packet, it replies with an address
  7978. assignment packet. The destination is the assigned node address. If
  7979. the node does not receive the address assignment packet within 5
  7980. seconds, it retransmits the address request packet. The
  7981. retransmission continues until the node successfully receives the
  7982. address assignment packet.
  7983.  
  7984. Whenever a node detects a transmission error such as carrier loss or
  7985. out-of-synchronization, it SHOULD send an address request packet to
  7986. the control processor and verify its current address. In addition, a
  7987. node MUST verify its address by sending address request packets every
  7988.  
  7989.  
  7990.  
  7991. Murakami & Maruyama Informational [Page 3]
  7993. RFC 2173 MAPOS June 1997
  7994.  
  7995.  
  7996. 30 seconds. The switch regards them as keep-alive packets and
  7997. utilizes them to detect the node's status. If it has not received a
  7998. request packet for more than 90 seconds, it assumes that the node
  7999. went down. In addition, it also assumes the node went down when a
  8000. switch detects a SONET signal failure.
  8001.  
  8002. 4.2 Packet Format
  8003.  
  8004. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  8005. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  8006. information field contains the NSP packet as shown in Figure 3.
  8007.  
  8008.  
  8009. +-----------+------------+
  8010. I command I address I
  8011. +-----------+------------+
  8012. I<- 32bit ->I<- 32 bit ->I
  8013.  
  8014. Figure 3 NSP packet format
  8015.  
  8016. The command field is 32 bits long and has the following values (in
  8017. decimal);
  8018.  
  8019. 1 address request
  8020. 2 address assignment
  8021. 3 reject(error)
  8022.  
  8023. The length of the address field is 32bits. In address request
  8024. packets, the NSP address field SHOULD be filled with zeroes, although
  8025. the switch ignores it. In address assignment packets, the assigned
  8026. address is placed in the least significant byte of the field. The
  8027. rest of the field is padded with zeroes. When the switch can not
  8028. assign the address for some reason, the switch replies with a reject
  8029. command (the values is 3). The value of the address field is
  8030. undefined.
  8031.  
  8032. 4.3 Consideration for special cases
  8033.  
  8034. There are two special cases to consider. One is a point-to-point
  8035. connection without a switch. The other is loop-back, that is, direct
  8036. connection between the input and the output of the same port.
  8037.  
  8038. 4.3.1 point-to-point
  8039.  
  8040. In the case of a point-to-point connection shown in Figure 4, a node
  8041. sends an address request packet to the other node. The destination
  8042. address is 00000001(0x01), that is usually a control processor in a
  8043. switch. When a node receives the address request, it detects the
  8044.  
  8045.  
  8046.  
  8047. Murakami & Maruyama Informational [Page 4]
  8049. RFC 2173 MAPOS June 1997
  8050.  
  8051.  
  8052. point-to-point connection by examining both the destination address
  8053. and the command contained. Then, it MUST reply with an address
  8054. assignment packet. The assigned address MUST be 00000011(0x03). Since
  8055. both nodes send an address request to each other, both of them get
  8056. address 00000011(0x03). Since any address can be used in point-to-
  8057. point environment, there is no problem even if both of the nodes have
  8058. the same address.
  8059.  
  8060. ---- address request ----> 0x01
  8061. 0x03 <---- address assignment ----
  8062. +------+ +------+
  8063. | node +--------------------------------+ node |
  8064. +------+ +------+
  8065. 0x01 <---- address request ----
  8066. ---- address assignment ----> 0x03
  8067.  
  8068. Figure 4 Point-to-point connection
  8069.  
  8070. 4.3.2 loop-back
  8071.  
  8072. Another special case is loop-back where the output port of a node is
  8073. simply connected to its input port as shown in Figure 5. In this
  8074. case, the same mechanism as that for point-to-point can be applied
  8075. without modification. A node sends an address request packet
  8076. destined to 00000001(0x01). The node then receives the same packet.
  8077. Since the destination is 00000001(0x01), it replies with an address
  8078. assignment packet, containing the assigned address 00000011(0x03), to
  8079. the address 0000 0011(0x03). Thus, the node obtains the address
  8080. 00000011(0x03).
  8081.  
  8082. ---- address request ----> 0x01
  8083. +------+ --- address assignment --> 0x03
  8084. | +-------------->-----------------+
  8085. | node + |
  8086. | +--------------<-----------------+
  8087. +------+
  8088.  
  8089. Figure 5 Loop-back Configuration
  8090.  
  8091.  
  8092.  
  8093.  
  8094.  
  8095.  
  8096.  
  8097.  
  8098.  
  8099.  
  8100.  
  8101.  
  8102.  
  8103. Murakami & Maruyama Informational [Page 5]
  8105. RFC 2173 MAPOS June 1997
  8106.  
  8107.  
  8108. 5. Security Considerations
  8109.  
  8110. Security issues are not discussed in this memo.
  8111.  
  8112. References
  8113.  
  8114. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  8115. over SONET/SDH, Version 1," RFC-2171, June 1997.
  8116.  
  8117. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  8118. Rates (1990).
  8119.  
  8120. [3] CCITT Recommendation G.708: Network Node Interface for
  8121. Synchronous Digital Hierarchy (1990).
  8122.  
  8123. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  8124. (1990).
  8125.  
  8126. [5] American National Standard for Telecommunications - Digital
  8127. Hierarchy - Optical Interface Rates and Formats Specification,
  8128. ANSI T1.105-1991.
  8129.  
  8130. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  8131. Numbers," RFC-2172, June, 1997.
  8132.  
  8133. Acknowledgements
  8134.  
  8135. The authors would like to acknowledge the contributions and
  8136. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  8137. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  8138.  
  8139. Authors' Address
  8140.  
  8141. Ken Murakami
  8142. NTT Software Laboratories
  8143. 3-9-11, Midori-cho
  8144. Musashino-shi
  8145. Tokyo 180, Japan
  8146. E-mail: murakami@ntt-20.ecl.net
  8147.  
  8148. Mitsuru Maruyama
  8149. NTT Software Laboratories
  8150. 3-9-11, Midori-cho
  8151. Musashino-shi
  8152. Tokyo 180, Japan
  8153. E-mail: mitsuru@ntt-20.ecl.net
  8154.  
  8155.  
  8156.  
  8157.  
  8158.  
  8159. Murakami & Maruyama Informational [Page 6]
  8161.  
  8162.  
  8163.  
  8164.  
  8165.  
  8166.  
  8167.  
  8168. Network Working Group K. Murakami
  8169. Request for Comments: 2173 M. Maruyama
  8170. Category: Informational NTT Laboratories
  8171. June 1997
  8172.  
  8173.  
  8174. A MAPOS version 1 Extension - Node Switch Protocol
  8175.  
  8176. Status of this Memo
  8177.  
  8178. This memo provides information for the Internet community. This memo
  8179. does not specify an Internet standard of any kind. Distribution of
  8180. this memo is unlimited.
  8181.  
  8182. Abstract
  8183.  
  8184. This document describes a MAPOS extension, Node Switch Protocol, for
  8185. automatic node address assignment. MAPOS is a multiple access
  8186. protocol for transmission of network-protocol datagrams, encapsulated
  8187. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  8188. automates the HDLC address configuration of each node. Using NSP, a
  8189. node retrieves its HDLC address from the switch to which it is
  8190. connected.
  8191.  
  8192. 1. Introduction
  8193.  
  8194. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  8195. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  8196. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  8197. switch provides multiple access capability to each node. In MAPOS,
  8198. each node has a unique HDLC address within a switch. The address is
  8199. equivalent to the port number of the switch to which the node is
  8200. connected. This document describes an extension to MAPOS, Node
  8201. Switch Protocol, which enable automatic HDLC address assignment.
  8202. First, it explains the addressing of MAPOS. Then, it describes the
  8203. NSP protocol for automatic HDLC node address assignment.
  8204.  
  8205. 2. Node Address Format
  8206.  
  8207. This section describes MAPOS Version 1 address format in single and
  8208. multiple switch environment.
  8209.  
  8210.  
  8211.  
  8212.  
  8213.  
  8214.  
  8215.  
  8216.  
  8217.  
  8218.  
  8219. Murakami & Maruyama Informational [Page 1]
  8221. RFC 2173 MAPOS June 1997
  8222.  
  8223.  
  8224. 2.1 Address Format
  8225.  
  8226. In MAPOS network, each end node has a unique HDLC address. As shown
  8227. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  8228. indicates the end of the field. When a SONET switch receives an HDLC
  8229. frame, it forwards the frame based on the address in the frame
  8230. header.
  8231.  
  8232. In unicast, MSB is 0 and the rest of the bits are the port number to
  8233. which a node is connected. Since the LSB is always 1, the minimum and
  8234. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  8235. reserved and is assigned to the control processor in a SONET switch.
  8236.  
  8237. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  8238. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  8239. indicate the group address.
  8240.  
  8241. +-------------+-+
  8242. | | | | | | | | |
  8243. | |port number|1|
  8244. +-+-----------+-+
  8245. ^ ^
  8246. | |
  8247. | +------- EA bit (always 1)
  8248. |
  8249. 1 : broadcast, multicast
  8250. 0 : unicast
  8251.  
  8252. Figure 1 Address format
  8253.  
  8254. 2.2 Address in multi-switch environment
  8255.  
  8256. In a multi-switch environment, variable-length subnet addressing is
  8257. used. Each switch has a switch number that is unique within the
  8258. system. Subnetted node addresses consist of the switch number and the
  8259. port number to which a node is connected. The address format is "0
  8260. <switch number> <node number> 1" for a unicast address, "all 1" for
  8261. the broadcast address, and "1 <group address> 1" for a multicast
  8262. address.
  8263.  
  8264. The address 0x01 is reserved and is assigned to the control processor
  8265. in the "local" switch. That is, it indicates the switch itself to
  8266. which the node is connected. The addresses of the form "0 <switch
  8267. number> <all 0> 1" are reserved, and indicates the control processor
  8268. of the switch designated by the switch number.
  8269.  
  8270. In Figure 2, the switch numbers are two bits long. Node N1 is
  8271. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  8272.  
  8273.  
  8274.  
  8275. Murakami & Maruyama Informational [Page 2]
  8277. RFC 2173 MAPOS June 1997
  8278.  
  8279.  
  8280. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  8281. has an address 01001001(0x49), since the switch number of S2 is 0x2
  8282. (10 in binary) and the port number is 0x09. Note that all the port
  8283. numbers are odd because the LSBs are always 1.
  8284.  
  8285. +------+
  8286. | node |
  8287. | N1 |
  8288. +------+
  8289. | 00100011(0x23)
  8290. |
  8291. |0x3 |0x3
  8292. +------+ +---+----+ +---+----+ +------+
  8293. | node +----+ SONET +-------+ SONET +-----+ node |
  8294. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  8295. +------+ | S1 | | S2 | +------+
  8296. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  8297. +---+----+ +---+----+
  8298. |0x7 |0x7
  8299.  
  8300.  
  8301. Figure 2 Addressing in Multiple Switch Environment
  8302.  
  8303. 4 NSP(Node-Switch Protocol)
  8304.  
  8305. This section describes the NSP protocol used for automatic node
  8306. address assignment.
  8307.  
  8308. 4.1 NSP protocol
  8309.  
  8310. NSP is introduced to provide an automatic node address assignment
  8311. function in MAPOS version 1. It reduces the administrative overhead
  8312. of node address configuration for each node and prevents troubles
  8313. such as address inconsistency and collision. When a node is connected
  8314. to a switch and receives SONET signal correctly, the node sends an
  8315. address request packet to the control processor in the local switch.
  8316. The destination address of this packet is 00000001(0x01). When the
  8317. control processor receives the packet, it replies with an address
  8318. assignment packet. The destination is the assigned node address. If
  8319. the node does not receive the address assignment packet within 5
  8320. seconds, it retransmits the address request packet. The
  8321. retransmission continues until the node successfully receives the
  8322. address assignment packet.
  8323.  
  8324. Whenever a node detects a transmission error such as carrier loss or
  8325. out-of-synchronization, it SHOULD send an address request packet to
  8326. the control processor and verify its current address. In addition, a
  8327. node MUST verify its address by sending address request packets every
  8328.  
  8329.  
  8330.  
  8331. Murakami & Maruyama Informational [Page 3]
  8333. RFC 2173 MAPOS June 1997
  8334.  
  8335.  
  8336. 30 seconds. The switch regards them as keep-alive packets and
  8337. utilizes them to detect the node's status. If it has not received a
  8338. request packet for more than 90 seconds, it assumes that the node
  8339. went down. In addition, it also assumes the node went down when a
  8340. switch detects a SONET signal failure.
  8341.  
  8342. 4.2 Packet Format
  8343.  
  8344. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  8345. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  8346. information field contains the NSP packet as shown in Figure 3.
  8347.  
  8348.  
  8349. +-----------+------------+
  8350. I command I address I
  8351. +-----------+------------+
  8352. I<- 32bit ->I<- 32 bit ->I
  8353.  
  8354. Figure 3 NSP packet format
  8355.  
  8356. The command field is 32 bits long and has the following values (in
  8357. decimal);
  8358.  
  8359. 1 address request
  8360. 2 address assignment
  8361. 3 reject(error)
  8362.  
  8363. The length of the address field is 32bits. In address request
  8364. packets, the NSP address field SHOULD be filled with zeroes, although
  8365. the switch ignores it. In address assignment packets, the assigned
  8366. address is placed in the least significant byte of the field. The
  8367. rest of the field is padded with zeroes. When the switch can not
  8368. assign the address for some reason, the switch replies with a reject
  8369. command (the values is 3). The value of the address field is
  8370. undefined.
  8371.  
  8372. 4.3 Consideration for special cases
  8373.  
  8374. There are two special cases to consider. One is a point-to-point
  8375. connection without a switch. The other is loop-back, that is, direct
  8376. connection between the input and the output of the same port.
  8377.  
  8378. 4.3.1 point-to-point
  8379.  
  8380. In the case of a point-to-point connection shown in Figure 4, a node
  8381. sends an address request packet to the other node. The destination
  8382. address is 00000001(0x01), that is usually a control processor in a
  8383. switch. When a node receives the address request, it detects the
  8384.  
  8385.  
  8386.  
  8387. Murakami & Maruyama Informational [Page 4]
  8389. RFC 2173 MAPOS June 1997
  8390.  
  8391.  
  8392. point-to-point connection by examining both the destination address
  8393. and the command contained. Then, it MUST reply with an address
  8394. assignment packet. The assigned address MUST be 00000011(0x03). Since
  8395. both nodes send an address request to each other, both of them get
  8396. address 00000011(0x03). Since any address can be used in point-to-
  8397. point environment, there is no problem even if both of the nodes have
  8398. the same address.
  8399.  
  8400. ---- address request ----> 0x01
  8401. 0x03 <---- address assignment ----
  8402. +------+ +------+
  8403. | node +--------------------------------+ node |
  8404. +------+ +------+
  8405. 0x01 <---- address request ----
  8406. ---- address assignment ----> 0x03
  8407.  
  8408. Figure 4 Point-to-point connection
  8409.  
  8410. 4.3.2 loop-back
  8411.  
  8412. Another special case is loop-back where the output port of a node is
  8413. simply connected to its input port as shown in Figure 5. In this
  8414. case, the same mechanism as that for point-to-point can be applied
  8415. without modification. A node sends an address request packet
  8416. destined to 00000001(0x01). The node then receives the same packet.
  8417. Since the destination is 00000001(0x01), it replies with an address
  8418. assignment packet, containing the assigned address 00000011(0x03), to
  8419. the address 0000 0011(0x03). Thus, the node obtains the address
  8420. 00000011(0x03).
  8421.  
  8422. ---- address request ----> 0x01
  8423. +------+ --- address assignment --> 0x03
  8424. | +-------------->-----------------+
  8425. | node + |
  8426. | +--------------<-----------------+
  8427. +------+
  8428.  
  8429. Figure 5 Loop-back Configuration
  8430.  
  8431.  
  8432.  
  8433.  
  8434.  
  8435.  
  8436.  
  8437.  
  8438.  
  8439.  
  8440.  
  8441.  
  8442.  
  8443. Murakami & Maruyama Informational [Page 5]
  8445. RFC 2173 MAPOS June 1997
  8446.  
  8447.  
  8448. 5. Security Considerations
  8449.  
  8450. Security issues are not discussed in this memo.
  8451.  
  8452. References
  8453.  
  8454. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  8455. over SONET/SDH, Version 1," RFC-2171, June 1997.
  8456.  
  8457. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  8458. Rates (1990).
  8459.  
  8460. [3] CCITT Recommendation G.708: Network Node Interface for
  8461. Synchronous Digital Hierarchy (1990).
  8462.  
  8463. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  8464. (1990).
  8465.  
  8466. [5] American National Standard for Telecommunications - Digital
  8467. Hierarchy - Optical Interface Rates and Formats Specification,
  8468. ANSI T1.105-1991.
  8469.  
  8470. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  8471. Numbers," RFC-2172, June, 1997.
  8472.  
  8473. Acknowledgements
  8474.  
  8475. The authors would like to acknowledge the contributions and
  8476. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  8477. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  8478.  
  8479. Authors' Address
  8480.  
  8481. Ken Murakami
  8482. NTT Software Laboratories
  8483. 3-9-11, Midori-cho
  8484. Musashino-shi
  8485. Tokyo 180, Japan
  8486. E-mail: murakami@ntt-20.ecl.net
  8487.  
  8488. Mitsuru Maruyama
  8489. NTT Software Laboratories
  8490. 3-9-11, Midori-cho
  8491. Musashino-shi
  8492. Tokyo 180, Japan
  8493. E-mail: mitsuru@ntt-20.ecl.net
  8494.  
  8495.  
  8496.  
  8497.  
  8498.  
  8499. Murakami & Maruyama Informational [Page 6]
  8501.  
  8502.  
  8503.  
  8504.  
  8505.  
  8506.  
  8507.  
  8508. Network Working Group K. Murakami
  8509. Request for Comments: 2173 M. Maruyama
  8510. Category: Informational NTT Laboratories
  8511. June 1997
  8512.  
  8513.  
  8514. A MAPOS version 1 Extension - Node Switch Protocol
  8515.  
  8516. Status of this Memo
  8517.  
  8518. This memo provides information for the Internet community. This memo
  8519. does not specify an Internet standard of any kind. Distribution of
  8520. this memo is unlimited.
  8521.  
  8522. Abstract
  8523.  
  8524. This document describes a MAPOS extension, Node Switch Protocol, for
  8525. automatic node address assignment. MAPOS is a multiple access
  8526. protocol for transmission of network-protocol datagrams, encapsulated
  8527. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  8528. automates the HDLC address configuration of each node. Using NSP, a
  8529. node retrieves its HDLC address from the switch to which it is
  8530. connected.
  8531.  
  8532. 1. Introduction
  8533.  
  8534. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  8535. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  8536. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  8537. switch provides multiple access capability to each node. In MAPOS,
  8538. each node has a unique HDLC address within a switch. The address is
  8539. equivalent to the port number of the switch to which the node is
  8540. connected. This document describes an extension to MAPOS, Node
  8541. Switch Protocol, which enable automatic HDLC address assignment.
  8542. First, it explains the addressing of MAPOS. Then, it describes the
  8543. NSP protocol for automatic HDLC node address assignment.
  8544.  
  8545. 2. Node Address Format
  8546.  
  8547. This section describes MAPOS Version 1 address format in single and
  8548. multiple switch environment.
  8549.  
  8550.  
  8551.  
  8552.  
  8553.  
  8554.  
  8555.  
  8556.  
  8557.  
  8558.  
  8559. Murakami & Maruyama Informational [Page 1]
  8561. RFC 2173 MAPOS June 1997
  8562.  
  8563.  
  8564. 2.1 Address Format
  8565.  
  8566. In MAPOS network, each end node has a unique HDLC address. As shown
  8567. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  8568. indicates the end of the field. When a SONET switch receives an HDLC
  8569. frame, it forwards the frame based on the address in the frame
  8570. header.
  8571.  
  8572. In unicast, MSB is 0 and the rest of the bits are the port number to
  8573. which a node is connected. Since the LSB is always 1, the minimum and
  8574. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  8575. reserved and is assigned to the control processor in a SONET switch.
  8576.  
  8577. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  8578. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  8579. indicate the group address.
  8580.  
  8581. +-------------+-+
  8582. | | | | | | | | |
  8583. | |port number|1|
  8584. +-+-----------+-+
  8585. ^ ^
  8586. | |
  8587. | +------- EA bit (always 1)
  8588. |
  8589. 1 : broadcast, multicast
  8590. 0 : unicast
  8591.  
  8592. Figure 1 Address format
  8593.  
  8594. 2.2 Address in multi-switch environment
  8595.  
  8596. In a multi-switch environment, variable-length subnet addressing is
  8597. used. Each switch has a switch number that is unique within the
  8598. system. Subnetted node addresses consist of the switch number and the
  8599. port number to which a node is connected. The address format is "0
  8600. <switch number> <node number> 1" for a unicast address, "all 1" for
  8601. the broadcast address, and "1 <group address> 1" for a multicast
  8602. address.
  8603.  
  8604. The address 0x01 is reserved and is assigned to the control processor
  8605. in the "local" switch. That is, it indicates the switch itself to
  8606. which the node is connected. The addresses of the form "0 <switch
  8607. number> <all 0> 1" are reserved, and indicates the control processor
  8608. of the switch designated by the switch number.
  8609.  
  8610. In Figure 2, the switch numbers are two bits long. Node N1 is
  8611. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  8612.  
  8613.  
  8614.  
  8615. Murakami & Maruyama Informational [Page 2]
  8617. RFC 2173 MAPOS June 1997
  8618.  
  8619.  
  8620. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  8621. has an address 01001001(0x49), since the switch number of S2 is 0x2
  8622. (10 in binary) and the port number is 0x09. Note that all the port
  8623. numbers are odd because the LSBs are always 1.
  8624.  
  8625. +------+
  8626. | node |
  8627. | N1 |
  8628. +------+
  8629. | 00100011(0x23)
  8630. |
  8631. |0x3 |0x3
  8632. +------+ +---+----+ +---+----+ +------+
  8633. | node +----+ SONET +-------+ SONET +-----+ node |
  8634. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  8635. +------+ | S1 | | S2 | +------+
  8636. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  8637. +---+----+ +---+----+
  8638. |0x7 |0x7
  8639.  
  8640.  
  8641. Figure 2 Addressing in Multiple Switch Environment
  8642.  
  8643. 4 NSP(Node-Switch Protocol)
  8644.  
  8645. This section describes the NSP protocol used for automatic node
  8646. address assignment.
  8647.  
  8648. 4.1 NSP protocol
  8649.  
  8650. NSP is introduced to provide an automatic node address assignment
  8651. function in MAPOS version 1. It reduces the administrative overhead
  8652. of node address configuration for each node and prevents troubles
  8653. such as address inconsistency and collision. When a node is connected
  8654. to a switch and receives SONET signal correctly, the node sends an
  8655. address request packet to the control processor in the local switch.
  8656. The destination address of this packet is 00000001(0x01). When the
  8657. control processor receives the packet, it replies with an address
  8658. assignment packet. The destination is the assigned node address. If
  8659. the node does not receive the address assignment packet within 5
  8660. seconds, it retransmits the address request packet. The
  8661. retransmission continues until the node successfully receives the
  8662. address assignment packet.
  8663.  
  8664. Whenever a node detects a transmission error such as carrier loss or
  8665. out-of-synchronization, it SHOULD send an address request packet to
  8666. the control processor and verify its current address. In addition, a
  8667. node MUST verify its address by sending address request packets every
  8668.  
  8669.  
  8670.  
  8671. Murakami & Maruyama Informational [Page 3]
  8673. RFC 2173 MAPOS June 1997
  8674.  
  8675.  
  8676. 30 seconds. The switch regards them as keep-alive packets and
  8677. utilizes them to detect the node's status. If it has not received a
  8678. request packet for more than 90 seconds, it assumes that the node
  8679. went down. In addition, it also assumes the node went down when a
  8680. switch detects a SONET signal failure.
  8681.  
  8682. 4.2 Packet Format
  8683.  
  8684. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  8685. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  8686. information field contains the NSP packet as shown in Figure 3.
  8687.  
  8688.  
  8689. +-----------+------------+
  8690. I command I address I
  8691. +-----------+------------+
  8692. I<- 32bit ->I<- 32 bit ->I
  8693.  
  8694. Figure 3 NSP packet format
  8695.  
  8696. The command field is 32 bits long and has the following values (in
  8697. decimal);
  8698.  
  8699. 1 address request
  8700. 2 address assignment
  8701. 3 reject(error)
  8702.  
  8703. The length of the address field is 32bits. In address request
  8704. packets, the NSP address field SHOULD be filled with zeroes, although
  8705. the switch ignores it. In address assignment packets, the assigned
  8706. address is placed in the least significant byte of the field. The
  8707. rest of the field is padded with zeroes. When the switch can not
  8708. assign the address for some reason, the switch replies with a reject
  8709. command (the values is 3). The value of the address field is
  8710. undefined.
  8711.  
  8712. 4.3 Consideration for special cases
  8713.  
  8714. There are two special cases to consider. One is a point-to-point
  8715. connection without a switch. The other is loop-back, that is, direct
  8716. connection between the input and the output of the same port.
  8717.  
  8718. 4.3.1 point-to-point
  8719.  
  8720. In the case of a point-to-point connection shown in Figure 4, a node
  8721. sends an address request packet to the other node. The destination
  8722. address is 00000001(0x01), that is usually a control processor in a
  8723. switch. When a node receives the address request, it detects the
  8724.  
  8725.  
  8726.  
  8727. Murakami & Maruyama Informational [Page 4]
  8729. RFC 2173 MAPOS June 1997
  8730.  
  8731.  
  8732. point-to-point connection by examining both the destination address
  8733. and the command contained. Then, it MUST reply with an address
  8734. assignment packet. The assigned address MUST be 00000011(0x03). Since
  8735. both nodes send an address request to each other, both of them get
  8736. address 00000011(0x03). Since any address can be used in point-to-
  8737. point environment, there is no problem even if both of the nodes have
  8738. the same address.
  8739.  
  8740. ---- address request ----> 0x01
  8741. 0x03 <---- address assignment ----
  8742. +------+ +------+
  8743. | node +--------------------------------+ node |
  8744. +------+ +------+
  8745. 0x01 <---- address request ----
  8746. ---- address assignment ----> 0x03
  8747.  
  8748. Figure 4 Point-to-point connection
  8749.  
  8750. 4.3.2 loop-back
  8751.  
  8752. Another special case is loop-back where the output port of a node is
  8753. simply connected to its input port as shown in Figure 5. In this
  8754. case, the same mechanism as that for point-to-point can be applied
  8755. without modification. A node sends an address request packet
  8756. destined to 00000001(0x01). The node then receives the same packet.
  8757. Since the destination is 00000001(0x01), it replies with an address
  8758. assignment packet, containing the assigned address 00000011(0x03), to
  8759. the address 0000 0011(0x03). Thus, the node obtains the address
  8760. 00000011(0x03).
  8761.  
  8762. ---- address request ----> 0x01
  8763. +------+ --- address assignment --> 0x03
  8764. | +-------------->-----------------+
  8765. | node + |
  8766. | +--------------<-----------------+
  8767. +------+
  8768.  
  8769. Figure 5 Loop-back Configuration
  8770.  
  8771.  
  8772.  
  8773.  
  8774.  
  8775.  
  8776.  
  8777.  
  8778.  
  8779.  
  8780.  
  8781.  
  8782.  
  8783. Murakami & Maruyama Informational [Page 5]
  8785. RFC 2173 MAPOS June 1997
  8786.  
  8787.  
  8788. 5. Security Considerations
  8789.  
  8790. Security issues are not discussed in this memo.
  8791.  
  8792. References
  8793.  
  8794. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  8795. over SONET/SDH, Version 1," RFC-2171, June 1997.
  8796.  
  8797. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  8798. Rates (1990).
  8799.  
  8800. [3] CCITT Recommendation G.708: Network Node Interface for
  8801. Synchronous Digital Hierarchy (1990).
  8802.  
  8803. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  8804. (1990).
  8805.  
  8806. [5] American National Standard for Telecommunications - Digital
  8807. Hierarchy - Optical Interface Rates and Formats Specification,
  8808. ANSI T1.105-1991.
  8809.  
  8810. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  8811. Numbers," RFC-2172, June, 1997.
  8812.  
  8813. Acknowledgements
  8814.  
  8815. The authors would like to acknowledge the contributions and
  8816. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  8817. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  8818.  
  8819. Authors' Address
  8820.  
  8821. Ken Murakami
  8822. NTT Software Laboratories
  8823. 3-9-11, Midori-cho
  8824. Musashino-shi
  8825. Tokyo 180, Japan
  8826. E-mail: murakami@ntt-20.ecl.net
  8827.  
  8828. Mitsuru Maruyama
  8829. NTT Software Laboratories
  8830. 3-9-11, Midori-cho
  8831. Musashino-shi
  8832. Tokyo 180, Japan
  8833. E-mail: mitsuru@ntt-20.ecl.net
  8834.  
  8835.  
  8836.  
  8837.  
  8838.  
  8839. Murakami & Maruyama Informational [Page 6]
  8841.  
  8842.  
  8843.  
  8844.  
  8845.  
  8846.  
  8847.  
  8848. Network Working Group K. Murakami
  8849. Request for Comments: 2173 M. Maruyama
  8850. Category: Informational NTT Laboratories
  8851. June 1997
  8852.  
  8853.  
  8854. A MAPOS version 1 Extension - Node Switch Protocol
  8855.  
  8856. Status of this Memo
  8857.  
  8858. This memo provides information for the Internet community. This memo
  8859. does not specify an Internet standard of any kind. Distribution of
  8860. this memo is unlimited.
  8861.  
  8862. Abstract
  8863.  
  8864. This document describes a MAPOS extension, Node Switch Protocol, for
  8865. automatic node address assignment. MAPOS is a multiple access
  8866. protocol for transmission of network-protocol datagrams, encapsulated
  8867. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  8868. automates the HDLC address configuration of each node. Using NSP, a
  8869. node retrieves its HDLC address from the switch to which it is
  8870. connected.
  8871.  
  8872. 1. Introduction
  8873.  
  8874. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  8875. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  8876. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  8877. switch provides multiple access capability to each node. In MAPOS,
  8878. each node has a unique HDLC address within a switch. The address is
  8879. equivalent to the port number of the switch to which the node is
  8880. connected. This document describes an extension to MAPOS, Node
  8881. Switch Protocol, which enable automatic HDLC address assignment.
  8882. First, it explains the addressing of MAPOS. Then, it describes the
  8883. NSP protocol for automatic HDLC node address assignment.
  8884.  
  8885. 2. Node Address Format
  8886.  
  8887. This section describes MAPOS Version 1 address format in single and
  8888. multiple switch environment.
  8889.  
  8890.  
  8891.  
  8892.  
  8893.  
  8894.  
  8895.  
  8896.  
  8897.  
  8898.  
  8899. Murakami & Maruyama Informational [Page 1]
  8901. RFC 2173 MAPOS June 1997
  8902.  
  8903.  
  8904. 2.1 Address Format
  8905.  
  8906. In MAPOS network, each end node has a unique HDLC address. As shown
  8907. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  8908. indicates the end of the field. When a SONET switch receives an HDLC
  8909. frame, it forwards the frame based on the address in the frame
  8910. header.
  8911.  
  8912. In unicast, MSB is 0 and the rest of the bits are the port number to
  8913. which a node is connected. Since the LSB is always 1, the minimum and
  8914. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  8915. reserved and is assigned to the control processor in a SONET switch.
  8916.  
  8917. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  8918. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  8919. indicate the group address.
  8920.  
  8921. +-------------+-+
  8922. | | | | | | | | |
  8923. | |port number|1|
  8924. +-+-----------+-+
  8925. ^ ^
  8926. | |
  8927. | +------- EA bit (always 1)
  8928. |
  8929. 1 : broadcast, multicast
  8930. 0 : unicast
  8931.  
  8932. Figure 1 Address format
  8933.  
  8934. 2.2 Address in multi-switch environment
  8935.  
  8936. In a multi-switch environment, variable-length subnet addressing is
  8937. used. Each switch has a switch number that is unique within the
  8938. system. Subnetted node addresses consist of the switch number and the
  8939. port number to which a node is connected. The address format is "0
  8940. <switch number> <node number> 1" for a unicast address, "all 1" for
  8941. the broadcast address, and "1 <group address> 1" for a multicast
  8942. address.
  8943.  
  8944. The address 0x01 is reserved and is assigned to the control processor
  8945. in the "local" switch. That is, it indicates the switch itself to
  8946. which the node is connected. The addresses of the form "0 <switch
  8947. number> <all 0> 1" are reserved, and indicates the control processor
  8948. of the switch designated by the switch number.
  8949.  
  8950. In Figure 2, the switch numbers are two bits long. Node N1 is
  8951. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  8952.  
  8953.  
  8954.  
  8955. Murakami & Maruyama Informational [Page 2]
  8957. RFC 2173 MAPOS June 1997
  8958.  
  8959.  
  8960. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  8961. has an address 01001001(0x49), since the switch number of S2 is 0x2
  8962. (10 in binary) and the port number is 0x09. Note that all the port
  8963. numbers are odd because the LSBs are always 1.
  8964.  
  8965. +------+
  8966. | node |
  8967. | N1 |
  8968. +------+
  8969. | 00100011(0x23)
  8970. |
  8971. |0x3 |0x3
  8972. +------+ +---+----+ +---+----+ +------+
  8973. | node +----+ SONET +-------+ SONET +-----+ node |
  8974. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  8975. +------+ | S1 | | S2 | +------+
  8976. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  8977. +---+----+ +---+----+
  8978. |0x7 |0x7
  8979.  
  8980.  
  8981. Figure 2 Addressing in Multiple Switch Environment
  8982.  
  8983. 4 NSP(Node-Switch Protocol)
  8984.  
  8985. This section describes the NSP protocol used for automatic node
  8986. address assignment.
  8987.  
  8988. 4.1 NSP protocol
  8989.  
  8990. NSP is introduced to provide an automatic node address assignment
  8991. function in MAPOS version 1. It reduces the administrative overhead
  8992. of node address configuration for each node and prevents troubles
  8993. such as address inconsistency and collision. When a node is connected
  8994. to a switch and receives SONET signal correctly, the node sends an
  8995. address request packet to the control processor in the local switch.
  8996. The destination address of this packet is 00000001(0x01). When the
  8997. control processor receives the packet, it replies with an address
  8998. assignment packet. The destination is the assigned node address. If
  8999. the node does not receive the address assignment packet within 5
  9000. seconds, it retransmits the address request packet. The
  9001. retransmission continues until the node successfully receives the
  9002. address assignment packet.
  9003.  
  9004. Whenever a node detects a transmission error such as carrier loss or
  9005. out-of-synchronization, it SHOULD send an address request packet to
  9006. the control processor and verify its current address. In addition, a
  9007. node MUST verify its address by sending address request packets every
  9008.  
  9009.  
  9010.  
  9011. Murakami & Maruyama Informational [Page 3]
  9013. RFC 2173 MAPOS June 1997
  9014.  
  9015.  
  9016. 30 seconds. The switch regards them as keep-alive packets and
  9017. utilizes them to detect the node's status. If it has not received a
  9018. request packet for more than 90 seconds, it assumes that the node
  9019. went down. In addition, it also assumes the node went down when a
  9020. switch detects a SONET signal failure.
  9021.  
  9022. 4.2 Packet Format
  9023.  
  9024. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  9025. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  9026. information field contains the NSP packet as shown in Figure 3.
  9027.  
  9028.  
  9029. +-----------+------------+
  9030. I command I address I
  9031. +-----------+------------+
  9032. I<- 32bit ->I<- 32 bit ->I
  9033.  
  9034. Figure 3 NSP packet format
  9035.  
  9036. The command field is 32 bits long and has the following values (in
  9037. decimal);
  9038.  
  9039. 1 address request
  9040. 2 address assignment
  9041. 3 reject(error)
  9042.  
  9043. The length of the address field is 32bits. In address request
  9044. packets, the NSP address field SHOULD be filled with zeroes, although
  9045. the switch ignores it. In address assignment packets, the assigned
  9046. address is placed in the least significant byte of the field. The
  9047. rest of the field is padded with zeroes. When the switch can not
  9048. assign the address for some reason, the switch replies with a reject
  9049. command (the values is 3). The value of the address field is
  9050. undefined.
  9051.  
  9052. 4.3 Consideration for special cases
  9053.  
  9054. There are two special cases to consider. One is a point-to-point
  9055. connection without a switch. The other is loop-back, that is, direct
  9056. connection between the input and the output of the same port.
  9057.  
  9058. 4.3.1 point-to-point
  9059.  
  9060. In the case of a point-to-point connection shown in Figure 4, a node
  9061. sends an address request packet to the other node. The destination
  9062. address is 00000001(0x01), that is usually a control processor in a
  9063. switch. When a node receives the address request, it detects the
  9064.  
  9065.  
  9066.  
  9067. Murakami & Maruyama Informational [Page 4]
  9069. RFC 2173 MAPOS June 1997
  9070.  
  9071.  
  9072. point-to-point connection by examining both the destination address
  9073. and the command contained. Then, it MUST reply with an address
  9074. assignment packet. The assigned address MUST be 00000011(0x03). Since
  9075. both nodes send an address request to each other, both of them get
  9076. address 00000011(0x03). Since any address can be used in point-to-
  9077. point environment, there is no problem even if both of the nodes have
  9078. the same address.
  9079.  
  9080. ---- address request ----> 0x01
  9081. 0x03 <---- address assignment ----
  9082. +------+ +------+
  9083. | node +--------------------------------+ node |
  9084. +------+ +------+
  9085. 0x01 <---- address request ----
  9086. ---- address assignment ----> 0x03
  9087.  
  9088. Figure 4 Point-to-point connection
  9089.  
  9090. 4.3.2 loop-back
  9091.  
  9092. Another special case is loop-back where the output port of a node is
  9093. simply connected to its input port as shown in Figure 5. In this
  9094. case, the same mechanism as that for point-to-point can be applied
  9095. without modification. A node sends an address request packet
  9096. destined to 00000001(0x01). The node then receives the same packet.
  9097. Since the destination is 00000001(0x01), it replies with an address
  9098. assignment packet, containing the assigned address 00000011(0x03), to
  9099. the address 0000 0011(0x03). Thus, the node obtains the address
  9100. 00000011(0x03).
  9101.  
  9102. ---- address request ----> 0x01
  9103. +------+ --- address assignment --> 0x03
  9104. | +-------------->-----------------+
  9105. | node + |
  9106. | +--------------<-----------------+
  9107. +------+
  9108.  
  9109. Figure 5 Loop-back Configuration
  9110.  
  9111.  
  9112.  
  9113.  
  9114.  
  9115.  
  9116.  
  9117.  
  9118.  
  9119.  
  9120.  
  9121.  
  9122.  
  9123. Murakami & Maruyama Informational [Page 5]
  9125. RFC 2173 MAPOS June 1997
  9126.  
  9127.  
  9128. 5. Security Considerations
  9129.  
  9130. Security issues are not discussed in this memo.
  9131.  
  9132. References
  9133.  
  9134. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  9135. over SONET/SDH, Version 1," RFC-2171, June 1997.
  9136.  
  9137. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  9138. Rates (1990).
  9139.  
  9140. [3] CCITT Recommendation G.708: Network Node Interface for
  9141. Synchronous Digital Hierarchy (1990).
  9142.  
  9143. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  9144. (1990).
  9145.  
  9146. [5] American National Standard for Telecommunications - Digital
  9147. Hierarchy - Optical Interface Rates and Formats Specification,
  9148. ANSI T1.105-1991.
  9149.  
  9150. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  9151. Numbers," RFC-2172, June, 1997.
  9152.  
  9153. Acknowledgements
  9154.  
  9155. The authors would like to acknowledge the contributions and
  9156. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  9157. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  9158.  
  9159. Authors' Address
  9160.  
  9161. Ken Murakami
  9162. NTT Software Laboratories
  9163. 3-9-11, Midori-cho
  9164. Musashino-shi
  9165. Tokyo 180, Japan
  9166. E-mail: murakami@ntt-20.ecl.net
  9167.  
  9168. Mitsuru Maruyama
  9169. NTT Software Laboratories
  9170. 3-9-11, Midori-cho
  9171. Musashino-shi
  9172. Tokyo 180, Japan
  9173. E-mail: mitsuru@ntt-20.ecl.net
  9174.  
  9175.  
  9176.  
  9177.  
  9178.  
  9179. Murakami & Maruyama Informational [Page 6]
  9181.  
  9182.  
  9183.  
  9184.  
  9185.  
  9186.  
  9187.  
  9188. Network Working Group K. Murakami
  9189. Request for Comments: 2173 M. Maruyama
  9190. Category: Informational NTT Laboratories
  9191. June 1997
  9192.  
  9193.  
  9194. A MAPOS version 1 Extension - Node Switch Protocol
  9195.  
  9196. Status of this Memo
  9197.  
  9198. This memo provides information for the Internet community. This memo
  9199. does not specify an Internet standard of any kind. Distribution of
  9200. this memo is unlimited.
  9201.  
  9202. Abstract
  9203.  
  9204. This document describes a MAPOS extension, Node Switch Protocol, for
  9205. automatic node address assignment. MAPOS is a multiple access
  9206. protocol for transmission of network-protocol datagrams, encapsulated
  9207. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  9208. automates the HDLC address configuration of each node. Using NSP, a
  9209. node retrieves its HDLC address from the switch to which it is
  9210. connected.
  9211.  
  9212. 1. Introduction
  9213.  
  9214. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  9215. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  9216. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  9217. switch provides multiple access capability to each node. In MAPOS,
  9218. each node has a unique HDLC address within a switch. The address is
  9219. equivalent to the port number of the switch to which the node is
  9220. connected. This document describes an extension to MAPOS, Node
  9221. Switch Protocol, which enable automatic HDLC address assignment.
  9222. First, it explains the addressing of MAPOS. Then, it describes the
  9223. NSP protocol for automatic HDLC node address assignment.
  9224.  
  9225. 2. Node Address Format
  9226.  
  9227. This section describes MAPOS Version 1 address format in single and
  9228. multiple switch environment.
  9229.  
  9230.  
  9231.  
  9232.  
  9233.  
  9234.  
  9235.  
  9236.  
  9237.  
  9238.  
  9239. Murakami & Maruyama Informational [Page 1]
  9241. RFC 2173 MAPOS June 1997
  9242.  
  9243.  
  9244. 2.1 Address Format
  9245.  
  9246. In MAPOS network, each end node has a unique HDLC address. As shown
  9247. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  9248. indicates the end of the field. When a SONET switch receives an HDLC
  9249. frame, it forwards the frame based on the address in the frame
  9250. header.
  9251.  
  9252. In unicast, MSB is 0 and the rest of the bits are the port number to
  9253. which a node is connected. Since the LSB is always 1, the minimum and
  9254. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  9255. reserved and is assigned to the control processor in a SONET switch.
  9256.  
  9257. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  9258. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  9259. indicate the group address.
  9260.  
  9261. +-------------+-+
  9262. | | | | | | | | |
  9263. | |port number|1|
  9264. +-+-----------+-+
  9265. ^ ^
  9266. | |
  9267. | +------- EA bit (always 1)
  9268. |
  9269. 1 : broadcast, multicast
  9270. 0 : unicast
  9271.  
  9272. Figure 1 Address format
  9273.  
  9274. 2.2 Address in multi-switch environment
  9275.  
  9276. In a multi-switch environment, variable-length subnet addressing is
  9277. used. Each switch has a switch number that is unique within the
  9278. system. Subnetted node addresses consist of the switch number and the
  9279. port number to which a node is connected. The address format is "0
  9280. <switch number> <node number> 1" for a unicast address, "all 1" for
  9281. the broadcast address, and "1 <group address> 1" for a multicast
  9282. address.
  9283.  
  9284. The address 0x01 is reserved and is assigned to the control processor
  9285. in the "local" switch. That is, it indicates the switch itself to
  9286. which the node is connected. The addresses of the form "0 <switch
  9287. number> <all 0> 1" are reserved, and indicates the control processor
  9288. of the switch designated by the switch number.
  9289.  
  9290. In Figure 2, the switch numbers are two bits long. Node N1 is
  9291. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  9292.  
  9293.  
  9294.  
  9295. Murakami & Maruyama Informational [Page 2]
  9297. RFC 2173 MAPOS June 1997
  9298.  
  9299.  
  9300. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  9301. has an address 01001001(0x49), since the switch number of S2 is 0x2
  9302. (10 in binary) and the port number is 0x09. Note that all the port
  9303. numbers are odd because the LSBs are always 1.
  9304.  
  9305. +------+
  9306. | node |
  9307. | N1 |
  9308. +------+
  9309. | 00100011(0x23)
  9310. |
  9311. |0x3 |0x3
  9312. +------+ +---+----+ +---+----+ +------+
  9313. | node +----+ SONET +-------+ SONET +-----+ node |
  9314. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  9315. +------+ | S1 | | S2 | +------+
  9316. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  9317. +---+----+ +---+----+
  9318. |0x7 |0x7
  9319.  
  9320.  
  9321. Figure 2 Addressing in Multiple Switch Environment
  9322.  
  9323. 4 NSP(Node-Switch Protocol)
  9324.  
  9325. This section describes the NSP protocol used for automatic node
  9326. address assignment.
  9327.  
  9328. 4.1 NSP protocol
  9329.  
  9330. NSP is introduced to provide an automatic node address assignment
  9331. function in MAPOS version 1. It reduces the administrative overhead
  9332. of node address configuration for each node and prevents troubles
  9333. such as address inconsistency and collision. When a node is connected
  9334. to a switch and receives SONET signal correctly, the node sends an
  9335. address request packet to the control processor in the local switch.
  9336. The destination address of this packet is 00000001(0x01). When the
  9337. control processor receives the packet, it replies with an address
  9338. assignment packet. The destination is the assigned node address. If
  9339. the node does not receive the address assignment packet within 5
  9340. seconds, it retransmits the address request packet. The
  9341. retransmission continues until the node successfully receives the
  9342. address assignment packet.
  9343.  
  9344. Whenever a node detects a transmission error such as carrier loss or
  9345. out-of-synchronization, it SHOULD send an address request packet to
  9346. the control processor and verify its current address. In addition, a
  9347. node MUST verify its address by sending address request packets every
  9348.  
  9349.  
  9350.  
  9351. Murakami & Maruyama Informational [Page 3]
  9353. RFC 2173 MAPOS June 1997
  9354.  
  9355.  
  9356. 30 seconds. The switch regards them as keep-alive packets and
  9357. utilizes them to detect the node's status. If it has not received a
  9358. request packet for more than 90 seconds, it assumes that the node
  9359. went down. In addition, it also assumes the node went down when a
  9360. switch detects a SONET signal failure.
  9361.  
  9362. 4.2 Packet Format
  9363.  
  9364. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  9365. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  9366. information field contains the NSP packet as shown in Figure 3.
  9367.  
  9368.  
  9369. +-----------+------------+
  9370. I command I address I
  9371. +-----------+------------+
  9372. I<- 32bit ->I<- 32 bit ->I
  9373.  
  9374. Figure 3 NSP packet format
  9375.  
  9376. The command field is 32 bits long and has the following values (in
  9377. decimal);
  9378.  
  9379. 1 address request
  9380. 2 address assignment
  9381. 3 reject(error)
  9382.  
  9383. The length of the address field is 32bits. In address request
  9384. packets, the NSP address field SHOULD be filled with zeroes, although
  9385. the switch ignores it. In address assignment packets, the assigned
  9386. address is placed in the least significant byte of the field. The
  9387. rest of the field is padded with zeroes. When the switch can not
  9388. assign the address for some reason, the switch replies with a reject
  9389. command (the values is 3). The value of the address field is
  9390. undefined.
  9391.  
  9392. 4.3 Consideration for special cases
  9393.  
  9394. There are two special cases to consider. One is a point-to-point
  9395. connection without a switch. The other is loop-back, that is, direct
  9396. connection between the input and the output of the same port.
  9397.  
  9398. 4.3.1 point-to-point
  9399.  
  9400. In the case of a point-to-point connection shown in Figure 4, a node
  9401. sends an address request packet to the other node. The destination
  9402. address is 00000001(0x01), that is usually a control processor in a
  9403. switch. When a node receives the address request, it detects the
  9404.  
  9405.  
  9406.  
  9407. Murakami & Maruyama Informational [Page 4]
  9409. RFC 2173 MAPOS June 1997
  9410.  
  9411.  
  9412. point-to-point connection by examining both the destination address
  9413. and the command contained. Then, it MUST reply with an address
  9414. assignment packet. The assigned address MUST be 00000011(0x03). Since
  9415. both nodes send an address request to each other, both of them get
  9416. address 00000011(0x03). Since any address can be used in point-to-
  9417. point environment, there is no problem even if both of the nodes have
  9418. the same address.
  9419.  
  9420. ---- address request ----> 0x01
  9421. 0x03 <---- address assignment ----
  9422. +------+ +------+
  9423. | node +--------------------------------+ node |
  9424. +------+ +------+
  9425. 0x01 <---- address request ----
  9426. ---- address assignment ----> 0x03
  9427.  
  9428. Figure 4 Point-to-point connection
  9429.  
  9430. 4.3.2 loop-back
  9431.  
  9432. Another special case is loop-back where the output port of a node is
  9433. simply connected to its input port as shown in Figure 5. In this
  9434. case, the same mechanism as that for point-to-point can be applied
  9435. without modification. A node sends an address request packet
  9436. destined to 00000001(0x01). The node then receives the same packet.
  9437. Since the destination is 00000001(0x01), it replies with an address
  9438. assignment packet, containing the assigned address 00000011(0x03), to
  9439. the address 0000 0011(0x03). Thus, the node obtains the address
  9440. 00000011(0x03).
  9441.  
  9442. ---- address request ----> 0x01
  9443. +------+ --- address assignment --> 0x03
  9444. | +-------------->-----------------+
  9445. | node + |
  9446. | +--------------<-----------------+
  9447. +------+
  9448.  
  9449. Figure 5 Loop-back Configuration
  9450.  
  9451.  
  9452.  
  9453.  
  9454.  
  9455.  
  9456.  
  9457.  
  9458.  
  9459.  
  9460.  
  9461.  
  9462.  
  9463. Murakami & Maruyama Informational [Page 5]
  9465. RFC 2173 MAPOS June 1997
  9466.  
  9467.  
  9468. 5. Security Considerations
  9469.  
  9470. Security issues are not discussed in this memo.
  9471.  
  9472. References
  9473.  
  9474. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  9475. over SONET/SDH, Version 1," RFC-2171, June 1997.
  9476.  
  9477. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  9478. Rates (1990).
  9479.  
  9480. [3] CCITT Recommendation G.708: Network Node Interface for
  9481. Synchronous Digital Hierarchy (1990).
  9482.  
  9483. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  9484. (1990).
  9485.  
  9486. [5] American National Standard for Telecommunications - Digital
  9487. Hierarchy - Optical Interface Rates and Formats Specification,
  9488. ANSI T1.105-1991.
  9489.  
  9490. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  9491. Numbers," RFC-2172, June, 1997.
  9492.  
  9493. Acknowledgements
  9494.  
  9495. The authors would like to acknowledge the contributions and
  9496. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  9497. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  9498.  
  9499. Authors' Address
  9500.  
  9501. Ken Murakami
  9502. NTT Software Laboratories
  9503. 3-9-11, Midori-cho
  9504. Musashino-shi
  9505. Tokyo 180, Japan
  9506. E-mail: murakami@ntt-20.ecl.net
  9507.  
  9508. Mitsuru Maruyama
  9509. NTT Software Laboratories
  9510. 3-9-11, Midori-cho
  9511. Musashino-shi
  9512. Tokyo 180, Japan
  9513. E-mail: mitsuru@ntt-20.ecl.net
  9514.  
  9515.  
  9516.  
  9517.  
  9518.  
  9519. Murakami & Maruyama Informational [Page 6]
  9521.  
  9522.  
  9523.  
  9524.  
  9525.  
  9526.  
  9527.  
  9528. Network Working Group K. Murakami
  9529. Request for Comments: 2173 M. Maruyama
  9530. Category: Informational NTT Laboratories
  9531. June 1997
  9532.  
  9533.  
  9534. A MAPOS version 1 Extension - Node Switch Protocol
  9535.  
  9536. Status of this Memo
  9537.  
  9538. This memo provides information for the Internet community. This memo
  9539. does not specify an Internet standard of any kind. Distribution of
  9540. this memo is unlimited.
  9541.  
  9542. Abstract
  9543.  
  9544. This document describes a MAPOS extension, Node Switch Protocol, for
  9545. automatic node address assignment. MAPOS is a multiple access
  9546. protocol for transmission of network-protocol datagrams, encapsulated
  9547. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  9548. automates the HDLC address configuration of each node. Using NSP, a
  9549. node retrieves its HDLC address from the switch to which it is
  9550. connected.
  9551.  
  9552. 1. Introduction
  9553.  
  9554. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  9555. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  9556. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  9557. switch provides multiple access capability to each node. In MAPOS,
  9558. each node has a unique HDLC address within a switch. The address is
  9559. equivalent to the port number of the switch to which the node is
  9560. connected. This document describes an extension to MAPOS, Node
  9561. Switch Protocol, which enable automatic HDLC address assignment.
  9562. First, it explains the addressing of MAPOS. Then, it describes the
  9563. NSP protocol for automatic HDLC node address assignment.
  9564.  
  9565. 2. Node Address Format
  9566.  
  9567. This section describes MAPOS Version 1 address format in single and
  9568. multiple switch environment.
  9569.  
  9570.  
  9571.  
  9572.  
  9573.  
  9574.  
  9575.  
  9576.  
  9577.  
  9578.  
  9579. Murakami & Maruyama Informational [Page 1]
  9581. RFC 2173 MAPOS June 1997
  9582.  
  9583.  
  9584. 2.1 Address Format
  9585.  
  9586. In MAPOS network, each end node has a unique HDLC address. As shown
  9587. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  9588. indicates the end of the field. When a SONET switch receives an HDLC
  9589. frame, it forwards the frame based on the address in the frame
  9590. header.
  9591.  
  9592. In unicast, MSB is 0 and the rest of the bits are the port number to
  9593. which a node is connected. Since the LSB is always 1, the minimum and
  9594. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  9595. reserved and is assigned to the control processor in a SONET switch.
  9596.  
  9597. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  9598. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  9599. indicate the group address.
  9600.  
  9601. +-------------+-+
  9602. | | | | | | | | |
  9603. | |port number|1|
  9604. +-+-----------+-+
  9605. ^ ^
  9606. | |
  9607. | +------- EA bit (always 1)
  9608. |
  9609. 1 : broadcast, multicast
  9610. 0 : unicast
  9611.  
  9612. Figure 1 Address format
  9613.  
  9614. 2.2 Address in multi-switch environment
  9615.  
  9616. In a multi-switch environment, variable-length subnet addressing is
  9617. used. Each switch has a switch number that is unique within the
  9618. system. Subnetted node addresses consist of the switch number and the
  9619. port number to which a node is connected. The address format is "0
  9620. <switch number> <node number> 1" for a unicast address, "all 1" for
  9621. the broadcast address, and "1 <group address> 1" for a multicast
  9622. address.
  9623.  
  9624. The address 0x01 is reserved and is assigned to the control processor
  9625. in the "local" switch. That is, it indicates the switch itself to
  9626. which the node is connected. The addresses of the form "0 <switch
  9627. number> <all 0> 1" are reserved, and indicates the control processor
  9628. of the switch designated by the switch number.
  9629.  
  9630. In Figure 2, the switch numbers are two bits long. Node N1 is
  9631. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  9632.  
  9633.  
  9634.  
  9635. Murakami & Maruyama Informational [Page 2]
  9637. RFC 2173 MAPOS June 1997
  9638.  
  9639.  
  9640. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  9641. has an address 01001001(0x49), since the switch number of S2 is 0x2
  9642. (10 in binary) and the port number is 0x09. Note that all the port
  9643. numbers are odd because the LSBs are always 1.
  9644.  
  9645. +------+
  9646. | node |
  9647. | N1 |
  9648. +------+
  9649. | 00100011(0x23)
  9650. |
  9651. |0x3 |0x3
  9652. +------+ +---+----+ +---+----+ +------+
  9653. | node +----+ SONET +-------+ SONET +-----+ node |
  9654. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  9655. +------+ | S1 | | S2 | +------+
  9656. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  9657. +---+----+ +---+----+
  9658. |0x7 |0x7
  9659.  
  9660.  
  9661. Figure 2 Addressing in Multiple Switch Environment
  9662.  
  9663. 4 NSP(Node-Switch Protocol)
  9664.  
  9665. This section describes the NSP protocol used for automatic node
  9666. address assignment.
  9667.  
  9668. 4.1 NSP protocol
  9669.  
  9670. NSP is introduced to provide an automatic node address assignment
  9671. function in MAPOS version 1. It reduces the administrative overhead
  9672. of node address configuration for each node and prevents troubles
  9673. such as address inconsistency and collision. When a node is connected
  9674. to a switch and receives SONET signal correctly, the node sends an
  9675. address request packet to the control processor in the local switch.
  9676. The destination address of this packet is 00000001(0x01). When the
  9677. control processor receives the packet, it replies with an address
  9678. assignment packet. The destination is the assigned node address. If
  9679. the node does not receive the address assignment packet within 5
  9680. seconds, it retransmits the address request packet. The
  9681. retransmission continues until the node successfully receives the
  9682. address assignment packet.
  9683.  
  9684. Whenever a node detects a transmission error such as carrier loss or
  9685. out-of-synchronization, it SHOULD send an address request packet to
  9686. the control processor and verify its current address. In addition, a
  9687. node MUST verify its address by sending address request packets every
  9688.  
  9689.  
  9690.  
  9691. Murakami & Maruyama Informational [Page 3]
  9693. RFC 2173 MAPOS June 1997
  9694.  
  9695.  
  9696. 30 seconds. The switch regards them as keep-alive packets and
  9697. utilizes them to detect the node's status. If it has not received a
  9698. request packet for more than 90 seconds, it assumes that the node
  9699. went down. In addition, it also assumes the node went down when a
  9700. switch detects a SONET signal failure.
  9701.  
  9702. 4.2 Packet Format
  9703.  
  9704. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  9705. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  9706. information field contains the NSP packet as shown in Figure 3.
  9707.  
  9708.  
  9709. +-----------+------------+
  9710. I command I address I
  9711. +-----------+------------+
  9712. I<- 32bit ->I<- 32 bit ->I
  9713.  
  9714. Figure 3 NSP packet format
  9715.  
  9716. The command field is 32 bits long and has the following values (in
  9717. decimal);
  9718.  
  9719. 1 address request
  9720. 2 address assignment
  9721. 3 reject(error)
  9722.  
  9723. The length of the address field is 32bits. In address request
  9724. packets, the NSP address field SHOULD be filled with zeroes, although
  9725. the switch ignores it. In address assignment packets, the assigned
  9726. address is placed in the least significant byte of the field. The
  9727. rest of the field is padded with zeroes. When the switch can not
  9728. assign the address for some reason, the switch replies with a reject
  9729. command (the values is 3). The value of the address field is
  9730. undefined.
  9731.  
  9732. 4.3 Consideration for special cases
  9733.  
  9734. There are two special cases to consider. One is a point-to-point
  9735. connection without a switch. The other is loop-back, that is, direct
  9736. connection between the input and the output of the same port.
  9737.  
  9738. 4.3.1 point-to-point
  9739.  
  9740. In the case of a point-to-point connection shown in Figure 4, a node
  9741. sends an address request packet to the other node. The destination
  9742. address is 00000001(0x01), that is usually a control processor in a
  9743. switch. When a node receives the address request, it detects the
  9744.  
  9745.  
  9746.  
  9747. Murakami & Maruyama Informational [Page 4]
  9749. RFC 2173 MAPOS June 1997
  9750.  
  9751.  
  9752. point-to-point connection by examining both the destination address
  9753. and the command contained. Then, it MUST reply with an address
  9754. assignment packet. The assigned address MUST be 00000011(0x03). Since
  9755. both nodes send an address request to each other, both of them get
  9756. address 00000011(0x03). Since any address can be used in point-to-
  9757. point environment, there is no problem even if both of the nodes have
  9758. the same address.
  9759.  
  9760. ---- address request ----> 0x01
  9761. 0x03 <---- address assignment ----
  9762. +------+ +------+
  9763. | node +--------------------------------+ node |
  9764. +------+ +------+
  9765. 0x01 <---- address request ----
  9766. ---- address assignment ----> 0x03
  9767.  
  9768. Figure 4 Point-to-point connection
  9769.  
  9770. 4.3.2 loop-back
  9771.  
  9772. Another special case is loop-back where the output port of a node is
  9773. simply connected to its input port as shown in Figure 5. In this
  9774. case, the same mechanism as that for point-to-point can be applied
  9775. without modification. A node sends an address request packet
  9776. destined to 00000001(0x01). The node then receives the same packet.
  9777. Since the destination is 00000001(0x01), it replies with an address
  9778. assignment packet, containing the assigned address 00000011(0x03), to
  9779. the address 0000 0011(0x03). Thus, the node obtains the address
  9780. 00000011(0x03).
  9781.  
  9782. ---- address request ----> 0x01
  9783. +------+ --- address assignment --> 0x03
  9784. | +-------------->-----------------+
  9785. | node + |
  9786. | +--------------<-----------------+
  9787. +------+
  9788.  
  9789. Figure 5 Loop-back Configuration
  9790.  
  9791.  
  9792.  
  9793.  
  9794.  
  9795.  
  9796.  
  9797.  
  9798.  
  9799.  
  9800.  
  9801.  
  9802.  
  9803. Murakami & Maruyama Informational [Page 5]
  9805. RFC 2173 MAPOS June 1997
  9806.  
  9807.  
  9808. 5. Security Considerations
  9809.  
  9810. Security issues are not discussed in this memo.
  9811.  
  9812. References
  9813.  
  9814. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  9815. over SONET/SDH, Version 1," RFC-2171, June 1997.
  9816.  
  9817. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  9818. Rates (1990).
  9819.  
  9820. [3] CCITT Recommendation G.708: Network Node Interface for
  9821. Synchronous Digital Hierarchy (1990).
  9822.  
  9823. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  9824. (1990).
  9825.  
  9826. [5] American National Standard for Telecommunications - Digital
  9827. Hierarchy - Optical Interface Rates and Formats Specification,
  9828. ANSI T1.105-1991.
  9829.  
  9830. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  9831. Numbers," RFC-2172, June, 1997.
  9832.  
  9833. Acknowledgements
  9834.  
  9835. The authors would like to acknowledge the contributions and
  9836. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  9837. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  9838.  
  9839. Authors' Address
  9840.  
  9841. Ken Murakami
  9842. NTT Software Laboratories
  9843. 3-9-11, Midori-cho
  9844. Musashino-shi
  9845. Tokyo 180, Japan
  9846. E-mail: murakami@ntt-20.ecl.net
  9847.  
  9848. Mitsuru Maruyama
  9849. NTT Software Laboratories
  9850. 3-9-11, Midori-cho
  9851. Musashino-shi
  9852. Tokyo 180, Japan
  9853. E-mail: mitsuru@ntt-20.ecl.net
  9854.  
  9855.  
  9856.  
  9857.  
  9858.  
  9859. Murakami & Maruyama Informational [Page 6]
  9861.  
  9862.  
  9863.  
  9864.  
  9865.  
  9866.  
  9867.  
  9868. Network Working Group K. Murakami
  9869. Request for Comments: 2173 M. Maruyama
  9870. Category: Informational NTT Laboratories
  9871. June 1997
  9872.  
  9873.  
  9874. A MAPOS version 1 Extension - Node Switch Protocol
  9875.  
  9876. Status of this Memo
  9877.  
  9878. This memo provides information for the Internet community. This memo
  9879. does not specify an Internet standard of any kind. Distribution of
  9880. this memo is unlimited.
  9881.  
  9882. Abstract
  9883.  
  9884. This document describes a MAPOS extension, Node Switch Protocol, for
  9885. automatic node address assignment. MAPOS is a multiple access
  9886. protocol for transmission of network-protocol datagrams, encapsulated
  9887. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  9888. automates the HDLC address configuration of each node. Using NSP, a
  9889. node retrieves its HDLC address from the switch to which it is
  9890. connected.
  9891.  
  9892. 1. Introduction
  9893.  
  9894. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  9895. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  9896. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  9897. switch provides multiple access capability to each node. In MAPOS,
  9898. each node has a unique HDLC address within a switch. The address is
  9899. equivalent to the port number of the switch to which the node is
  9900. connected. This document describes an extension to MAPOS, Node
  9901. Switch Protocol, which enable automatic HDLC address assignment.
  9902. First, it explains the addressing of MAPOS. Then, it describes the
  9903. NSP protocol for automatic HDLC node address assignment.
  9904.  
  9905. 2. Node Address Format
  9906.  
  9907. This section describes MAPOS Version 1 address format in single and
  9908. multiple switch environment.
  9909.  
  9910.  
  9911.  
  9912.  
  9913.  
  9914.  
  9915.  
  9916.  
  9917.  
  9918.  
  9919. Murakami & Maruyama Informational [Page 1]
  9921. RFC 2173 MAPOS June 1997
  9922.  
  9923.  
  9924. 2.1 Address Format
  9925.  
  9926. In MAPOS network, each end node has a unique HDLC address. As shown
  9927. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  9928. indicates the end of the field. When a SONET switch receives an HDLC
  9929. frame, it forwards the frame based on the address in the frame
  9930. header.
  9931.  
  9932. In unicast, MSB is 0 and the rest of the bits are the port number to
  9933. which a node is connected. Since the LSB is always 1, the minimum and
  9934. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  9935. reserved and is assigned to the control processor in a SONET switch.
  9936.  
  9937. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  9938. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  9939. indicate the group address.
  9940.  
  9941. +-------------+-+
  9942. | | | | | | | | |
  9943. | |port number|1|
  9944. +-+-----------+-+
  9945. ^ ^
  9946. | |
  9947. | +------- EA bit (always 1)
  9948. |
  9949. 1 : broadcast, multicast
  9950. 0 : unicast
  9951.  
  9952. Figure 1 Address format
  9953.  
  9954. 2.2 Address in multi-switch environment
  9955.  
  9956. In a multi-switch environment, variable-length subnet addressing is
  9957. used. Each switch has a switch number that is unique within the
  9958. system. Subnetted node addresses consist of the switch number and the
  9959. port number to which a node is connected. The address format is "0
  9960. <switch number> <node number> 1" for a unicast address, "all 1" for
  9961. the broadcast address, and "1 <group address> 1" for a multicast
  9962. address.
  9963.  
  9964. The address 0x01 is reserved and is assigned to the control processor
  9965. in the "local" switch. That is, it indicates the switch itself to
  9966. which the node is connected. The addresses of the form "0 <switch
  9967. number> <all 0> 1" are reserved, and indicates the control processor
  9968. of the switch designated by the switch number.
  9969.  
  9970. In Figure 2, the switch numbers are two bits long. Node N1 is
  9971. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  9972.  
  9973.  
  9974.  
  9975. Murakami & Maruyama Informational [Page 2]
  9977. RFC 2173 MAPOS June 1997
  9978.  
  9979.  
  9980. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  9981. has an address 01001001(0x49), since the switch number of S2 is 0x2
  9982. (10 in binary) and the port number is 0x09. Note that all the port
  9983. numbers are odd because the LSBs are always 1.
  9984.  
  9985. +------+
  9986. | node |
  9987. | N1 |
  9988. +------+
  9989. | 00100011(0x23)
  9990. |
  9991. |0x3 |0x3
  9992. +------+ +---+----+ +---+----+ +------+
  9993. | node +----+ SONET +-------+ SONET +-----+ node |
  9994. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  9995. +------+ | S1 | | S2 | +------+
  9996. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  9997. +---+----+ +---+----+
  9998. |0x7 |0x7
  9999.  
  10000.  
  10001. Figure 2 Addressing in Multiple Switch Environment
  10002.  
  10003. 4 NSP(Node-Switch Protocol)
  10004.  
  10005. This section describes the NSP protocol used for automatic node
  10006. address assignment.
  10007.  
  10008. 4.1 NSP protocol
  10009.  
  10010. NSP is introduced to provide an automatic node address assignment
  10011. function in MAPOS version 1. It reduces the administrative overhead
  10012. of node address configuration for each node and prevents troubles
  10013. such as address inconsistency and collision. When a node is connected
  10014. to a switch and receives SONET signal correctly, the node sends an
  10015. address request packet to the control processor in the local switch.
  10016. The destination address of this packet is 00000001(0x01). When the
  10017. control processor receives the packet, it replies with an address
  10018. assignment packet. The destination is the assigned node address. If
  10019. the node does not receive the address assignment packet within 5
  10020. seconds, it retransmits the address request packet. The
  10021. retransmission continues until the node successfully receives the
  10022. address assignment packet.
  10023.  
  10024. Whenever a node detects a transmission error such as carrier loss or
  10025. out-of-synchronization, it SHOULD send an address request packet to
  10026. the control processor and verify its current address. In addition, a
  10027. node MUST verify its address by sending address request packets every
  10028.  
  10029.  
  10030.  
  10031. Murakami & Maruyama Informational [Page 3]
  10033. RFC 2173 MAPOS June 1997
  10034.  
  10035.  
  10036. 30 seconds. The switch regards them as keep-alive packets and
  10037. utilizes them to detect the node's status. If it has not received a
  10038. request packet for more than 90 seconds, it assumes that the node
  10039. went down. In addition, it also assumes the node went down when a
  10040. switch detects a SONET signal failure.
  10041.  
  10042. 4.2 Packet Format
  10043.  
  10044. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  10045. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  10046. information field contains the NSP packet as shown in Figure 3.
  10047.  
  10048.  
  10049. +-----------+------------+
  10050. I command I address I
  10051. +-----------+------------+
  10052. I<- 32bit ->I<- 32 bit ->I
  10053.  
  10054. Figure 3 NSP packet format
  10055.  
  10056. The command field is 32 bits long and has the following values (in
  10057. decimal);
  10058.  
  10059. 1 address request
  10060. 2 address assignment
  10061. 3 reject(error)
  10062.  
  10063. The length of the address field is 32bits. In address request
  10064. packets, the NSP address field SHOULD be filled with zeroes, although
  10065. the switch ignores it. In address assignment packets, the assigned
  10066. address is placed in the least significant byte of the field. The
  10067. rest of the field is padded with zeroes. When the switch can not
  10068. assign the address for some reason, the switch replies with a reject
  10069. command (the values is 3). The value of the address field is
  10070. undefined.
  10071.  
  10072. 4.3 Consideration for special cases
  10073.  
  10074. There are two special cases to consider. One is a point-to-point
  10075. connection without a switch. The other is loop-back, that is, direct
  10076. connection between the input and the output of the same port.
  10077.  
  10078. 4.3.1 point-to-point
  10079.  
  10080. In the case of a point-to-point connection shown in Figure 4, a node
  10081. sends an address request packet to the other node. The destination
  10082. address is 00000001(0x01), that is usually a control processor in a
  10083. switch. When a node receives the address request, it detects the
  10084.  
  10085.  
  10086.  
  10087. Murakami & Maruyama Informational [Page 4]
  10089. RFC 2173 MAPOS June 1997
  10090.  
  10091.  
  10092. point-to-point connection by examining both the destination address
  10093. and the command contained. Then, it MUST reply with an address
  10094. assignment packet. The assigned address MUST be 00000011(0x03). Since
  10095. both nodes send an address request to each other, both of them get
  10096. address 00000011(0x03). Since any address can be used in point-to-
  10097. point environment, there is no problem even if both of the nodes have
  10098. the same address.
  10099.  
  10100. ---- address request ----> 0x01
  10101. 0x03 <---- address assignment ----
  10102. +------+ +------+
  10103. | node +--------------------------------+ node |
  10104. +------+ +------+
  10105. 0x01 <---- address request ----
  10106. ---- address assignment ----> 0x03
  10107.  
  10108. Figure 4 Point-to-point connection
  10109.  
  10110. 4.3.2 loop-back
  10111.  
  10112. Another special case is loop-back where the output port of a node is
  10113. simply connected to its input port as shown in Figure 5. In this
  10114. case, the same mechanism as that for point-to-point can be applied
  10115. without modification. A node sends an address request packet
  10116. destined to 00000001(0x01). The node then receives the same packet.
  10117. Since the destination is 00000001(0x01), it replies with an address
  10118. assignment packet, containing the assigned address 00000011(0x03), to
  10119. the address 0000 0011(0x03). Thus, the node obtains the address
  10120. 00000011(0x03).
  10121.  
  10122. ---- address request ----> 0x01
  10123. +------+ --- address assignment --> 0x03
  10124. | +-------------->-----------------+
  10125. | node + |
  10126. | +--------------<-----------------+
  10127. +------+
  10128.  
  10129. Figure 5 Loop-back Configuration
  10130.  
  10131.  
  10132.  
  10133.  
  10134.  
  10135.  
  10136.  
  10137.  
  10138.  
  10139.  
  10140.  
  10141.  
  10142.  
  10143. Murakami & Maruyama Informational [Page 5]
  10145. RFC 2173 MAPOS June 1997
  10146.  
  10147.  
  10148. 5. Security Considerations
  10149.  
  10150. Security issues are not discussed in this memo.
  10151.  
  10152. References
  10153.  
  10154. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  10155. over SONET/SDH, Version 1," RFC-2171, June 1997.
  10156.  
  10157. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  10158. Rates (1990).
  10159.  
  10160. [3] CCITT Recommendation G.708: Network Node Interface for
  10161. Synchronous Digital Hierarchy (1990).
  10162.  
  10163. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  10164. (1990).
  10165.  
  10166. [5] American National Standard for Telecommunications - Digital
  10167. Hierarchy - Optical Interface Rates and Formats Specification,
  10168. ANSI T1.105-1991.
  10169.  
  10170. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  10171. Numbers," RFC-2172, June, 1997.
  10172.  
  10173. Acknowledgements
  10174.  
  10175. The authors would like to acknowledge the contributions and
  10176. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  10177. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  10178.  
  10179. Authors' Address
  10180.  
  10181. Ken Murakami
  10182. NTT Software Laboratories
  10183. 3-9-11, Midori-cho
  10184. Musashino-shi
  10185. Tokyo 180, Japan
  10186. E-mail: murakami@ntt-20.ecl.net
  10187.  
  10188. Mitsuru Maruyama
  10189. NTT Software Laboratories
  10190. 3-9-11, Midori-cho
  10191. Musashino-shi
  10192. Tokyo 180, Japan
  10193. E-mail: mitsuru@ntt-20.ecl.net
  10194.  
  10195.  
  10196.  
  10197.  
  10198.  
  10199. Murakami & Maruyama Informational [Page 6]
  10201.  
  10202.  
  10203.  
  10204.  
  10205.  
  10206.  
  10207.  
  10208.  
  10209.  
  10210. Network Working Group K. Murakami
  10211. Request for Comments: 2173 M. Maruyama
  10212. Category: Informational NTT Laboratories
  10213. June 1997
  10214.  
  10215.  
  10216. A MAPOS version 1 Extension - Node Switch Protocol
  10217.  
  10218. Status of this Memo
  10219.  
  10220. This memo provides information for the Internet community. This memo
  10221. does not specify an Internet standard of any kind. Distribution of
  10222. this memo is unlimited.
  10223.  
  10224. Abstract
  10225.  
  10226. This document describes a MAPOS extension, Node Switch Protocol, for
  10227. automatic node address assignment. MAPOS is a multiple access
  10228. protocol for transmission of network-protocol datagrams, encapsulated
  10229. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  10230. automates the HDLC address configuration of each node. Using NSP, a
  10231. node retrieves its HDLC address from the switch to which it is
  10232. connected.
  10233.  
  10234. 1. Introduction
  10235.  
  10236. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  10237. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  10238. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  10239. switch provides multiple access capability to each node. In MAPOS,
  10240. each node has a unique HDLC address within a switch. The address is
  10241. equivalent to the port number of the switch to which the node is
  10242. connected. This document describes an extension to MAPOS, Node
  10243. Switch Protocol, which enable automatic HDLC address assignment.
  10244. First, it explains the addressing of MAPOS. Then, it describes the
  10245. NSP protocol for automatic HDLC node address assignment.
  10246.  
  10247. 2. Node Address Format
  10248.  
  10249. This section describes MAPOS Version 1 address format in single and
  10250. multiple switch environment.
  10251.  
  10252.  
  10253.  
  10254.  
  10255.  
  10256.  
  10257.  
  10258.  
  10259.  
  10260.  
  10261. Murakami & Maruyama Informational [Page 1]
  10263. RFC 2173 MAPOS June 1997
  10264.  
  10265.  
  10266. 2.1 Address Format
  10267.  
  10268. In MAPOS network, each end node has a unique HDLC address. As shown
  10269. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  10270. indicates the end of the field. When a SONET switch receives an HDLC
  10271. frame, it forwards the frame based on the address in the frame
  10272. header.
  10273.  
  10274. In unicast, MSB is 0 and the rest of the bits are the port number to
  10275. which a node is connected. Since the LSB is always 1, the minimum and
  10276. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  10277. reserved and is assigned to the control processor in a SONET switch.
  10278.  
  10279. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  10280. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  10281. indicate the group address.
  10282.  
  10283. +-------------+-+
  10284. | | | | | | | | |
  10285. | |port number|1|
  10286. +-+-----------+-+
  10287. ^ ^
  10288. | |
  10289. | +------- EA bit (always 1)
  10290. |
  10291. 1 : broadcast, multicast
  10292. 0 : unicast
  10293.  
  10294. Figure 1 Address format
  10295.  
  10296. 2.2 Address in multi-switch environment
  10297.  
  10298. In a multi-switch environment, variable-length subnet addressing is
  10299. used. Each switch has a switch number that is unique within the
  10300. system. Subnetted node addresses consist of the switch number and the
  10301. port number to which a node is connected. The address format is "0
  10302. <switch number> <node number> 1" for a unicast address, "all 1" for
  10303. the broadcast address, and "1 <group address> 1" for a multicast
  10304. address.
  10305.  
  10306. The address 0x01 is reserved and is assigned to the control processor
  10307. in the "local" switch. That is, it indicates the switch itself to
  10308. which the node is connected. The addresses of the form "0 <switch
  10309. number> <all 0> 1" are reserved, and indicates the control processor
  10310. of the switch designated by the switch number.
  10311.  
  10312. In Figure 2, the switch numbers are two bits long. Node N1 is
  10313. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  10314.  
  10315.  
  10316.  
  10317. Murakami & Maruyama Informational [Page 2]
  10319. RFC 2173 MAPOS June 1997
  10320.  
  10321.  
  10322. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  10323. has an address 01001001(0x49), since the switch number of S2 is 0x2
  10324. (10 in binary) and the port number is 0x09. Note that all the port
  10325. numbers are odd because the LSBs are always 1.
  10326.  
  10327. +------+
  10328. | node |
  10329. | N1 |
  10330. +------+
  10331. | 00100011(0x23)
  10332. |
  10333. |0x3 |0x3
  10334. +------+ +---+----+ +---+----+ +------+
  10335. | node +----+ SONET +-------+ SONET +-----+ node |
  10336. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  10337. +------+ | S1 | | S2 | +------+
  10338. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  10339. +---+----+ +---+----+
  10340. |0x7 |0x7
  10341.  
  10342.  
  10343. Figure 2 Addressing in Multiple Switch Environment
  10344.  
  10345. 4 NSP(Node-Switch Protocol)
  10346.  
  10347. This section describes the NSP protocol used for automatic node
  10348. address assignment.
  10349.  
  10350. 4.1 NSP protocol
  10351.  
  10352. NSP is introduced to provide an automatic node address assignment
  10353. function in MAPOS version 1. It reduces the administrative overhead
  10354. of node address configuration for each node and prevents troubles
  10355. such as address inconsistency and collision. When a node is connected
  10356. to a switch and receives SONET signal correctly, the node sends an
  10357. address request packet to the control processor in the local switch.
  10358. The destination address of this packet is 00000001(0x01). When the
  10359. control processor receives the packet, it replies with an address
  10360. assignment packet. The destination is the assigned node address. If
  10361. the node does not receive the address assignment packet within 5
  10362. seconds, it retransmits the address request packet. The
  10363. retransmission continues until the node successfully receives the
  10364. address assignment packet.
  10365.  
  10366. Whenever a node detects a transmission error such as carrier loss or
  10367. out-of-synchronization, it SHOULD send an address request packet to
  10368. the control processor and verify its current address. In addition, a
  10369. node MUST verify its address by sending address request packets every
  10370.  
  10371.  
  10372.  
  10373. Murakami & Maruyama Informational [Page 3]
  10375. RFC 2173 MAPOS June 1997
  10376.  
  10377.  
  10378. 30 seconds. The switch regards them as keep-alive packets and
  10379. utilizes them to detect the node's status. If it has not received a
  10380. request packet for more than 90 seconds, it assumes that the node
  10381. went down. In addition, it also assumes the node went down when a
  10382. switch detects a SONET signal failure.
  10383.  
  10384. 4.2 Packet Format
  10385.  
  10386. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  10387. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  10388. information field contains the NSP packet as shown in Figure 3.
  10389.  
  10390.  
  10391. +-----------+------------+
  10392. I command I address I
  10393. +-----------+------------+
  10394. I<- 32bit ->I<- 32 bit ->I
  10395.  
  10396. Figure 3 NSP packet format
  10397.  
  10398. The command field is 32 bits long and has the following values (in
  10399. decimal);
  10400.  
  10401. 1 address request
  10402. 2 address assignment
  10403. 3 reject(error)
  10404.  
  10405. The length of the address field is 32bits. In address request
  10406. packets, the NSP address field SHOULD be filled with zeroes, although
  10407. the switch ignores it. In address assignment packets, the assigned
  10408. address is placed in the least significant byte of the field. The
  10409. rest of the field is padded with zeroes. When the switch can not
  10410. assign the address for some reason, the switch replies with a reject
  10411. command (the values is 3). The value of the address field is
  10412. undefined.
  10413.  
  10414. 4.3 Consideration for special cases
  10415.  
  10416. There are two special cases to consider. One is a point-to-point
  10417. connection without a switch. The other is loop-back, that is, direct
  10418. connection between the input and the output of the same port.
  10419.  
  10420. 4.3.1 point-to-point
  10421.  
  10422. In the case of a point-to-point connection shown in Figure 4, a node
  10423. sends an address request packet to the other node. The destination
  10424. address is 00000001(0x01), that is usually a control processor in a
  10425. switch. When a node receives the address request, it detects the
  10426.  
  10427.  
  10428.  
  10429. Murakami & Maruyama Informational [Page 4]
  10431. RFC 2173 MAPOS June 1997
  10432.  
  10433.  
  10434. point-to-point connection by examining both the destination address
  10435. and the command contained. Then, it MUST reply with an address
  10436. assignment packet. The assigned address MUST be 00000011(0x03). Since
  10437. both nodes send an address request to each other, both of them get
  10438. address 00000011(0x03). Since any address can be used in point-to-
  10439. point environment, there is no problem even if both of the nodes have
  10440. the same address.
  10441.  
  10442. ---- address request ----> 0x01
  10443. 0x03 <---- address assignment ----
  10444. +------+ +------+
  10445. | node +--------------------------------+ node |
  10446. +------+ +------+
  10447. 0x01 <---- address request ----
  10448. ---- address assignment ----> 0x03
  10449.  
  10450. Figure 4 Point-to-point connection
  10451.  
  10452. 4.3.2 loop-back
  10453.  
  10454. Another special case is loop-back where the output port of a node is
  10455. simply connected to its input port as shown in Figure 5. In this
  10456. case, the same mechanism as that for point-to-point can be applied
  10457. without modification. A node sends an address request packet
  10458. destined to 00000001(0x01). The node then receives the same packet.
  10459. Since the destination is 00000001(0x01), it replies with an address
  10460. assignment packet, containing the assigned address 00000011(0x03), to
  10461. the address 0000 0011(0x03). Thus, the node obtains the address
  10462. 00000011(0x03).
  10463.  
  10464. ---- address request ----> 0x01
  10465. +------+ --- address assignment --> 0x03
  10466. | +-------------->-----------------+
  10467. | node + |
  10468. | +--------------<-----------------+
  10469. +------+
  10470.  
  10471. Figure 5 Loop-back Configuration
  10472.  
  10473.  
  10474.  
  10475.  
  10476.  
  10477.  
  10478.  
  10479.  
  10480.  
  10481.  
  10482.  
  10483.  
  10484.  
  10485. Murakami & Maruyama Informational [Page 5]
  10487. RFC 2173 MAPOS June 1997
  10488.  
  10489.  
  10490. 5. Security Considerations
  10491.  
  10492. Security issues are not discussed in this memo.
  10493.  
  10494. References
  10495.  
  10496. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  10497. over SONET/SDH, Version 1," RFC-2171, June 1997.
  10498.  
  10499. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  10500. Rates (1990).
  10501.  
  10502. [3] CCITT Recommendation G.708: Network Node Interface for
  10503. Synchronous Digital Hierarchy (1990).
  10504.  
  10505. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  10506. (1990).
  10507.  
  10508. [5] American National Standard for Telecommunications - Digital
  10509. Hierarchy - Optical Interface Rates and Formats Specification,
  10510. ANSI T1.105-1991.
  10511.  
  10512. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  10513. Numbers," RFC-2172, June, 1997.
  10514.  
  10515. Acknowledgements
  10516.  
  10517. The authors would like to acknowledge the contributions and
  10518. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  10519. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  10520.  
  10521. Authors' Address
  10522.  
  10523. Ken Murakami
  10524. NTT Software Laboratories
  10525. 3-9-11, Midori-cho
  10526. Musashino-shi
  10527. Tokyo 180, Japan
  10528. E-mail: murakami@ntt-20.ecl.net
  10529.  
  10530. Mitsuru Maruyama
  10531. NTT Software Laboratories
  10532. 3-9-11, Midori-cho
  10533. Musashino-shi
  10534. Tokyo 180, Japan
  10535. E-mail: mitsuru@ntt-20.ecl.net
  10536.  
  10537.  
  10538.  
  10539.  
  10540.  
  10541. Murakami & Maruyama Informational [Page 6]
  10542.  
  10543.  
  10544.  
  10545.  
  10546.  
  10547.  
  10548.  
  10549. Network Working Group K. Murakami
  10550. Request for Comments: 2173 M. Maruyama
  10551. Category: Informational NTT Laboratories
  10552. June 1997
  10553.  
  10554.  
  10555. A MAPOS version 1 Extension - Node Switch Protocol
  10556.  
  10557. Status of this Memo
  10558.  
  10559. This memo provides information for the Internet community. This memo
  10560. does not specify an Internet standard of any kind. Distribution of
  10561. this memo is unlimited.
  10562.  
  10563. Abstract
  10564.  
  10565. This document describes a MAPOS extension, Node Switch Protocol, for
  10566. automatic node address assignment. MAPOS is a multiple access
  10567. protocol for transmission of network-protocol datagrams, encapsulated
  10568. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  10569. automates the HDLC address configuration of each node. Using NSP, a
  10570. node retrieves its HDLC address from the switch to which it is
  10571. connected.
  10572.  
  10573. 1. Introduction
  10574.  
  10575. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  10576. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  10577. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  10578. switch provides multiple access capability to each node. In MAPOS,
  10579. each node has a unique HDLC address within a switch. The address is
  10580. equivalent to the port number of the switch to which the node is
  10581. connected. This document describes an extension to MAPOS, Node
  10582. Switch Protocol, which enable automatic HDLC address assignment.
  10583. First, it explains the addressing of MAPOS. Then, it describes the
  10584. NSP protocol for automatic HDLC node address assignment.
  10585.  
  10586. 2. Node Address Format
  10587.  
  10588. This section describes MAPOS Version 1 address format in single and
  10589. multiple switch environment.
  10590.  
  10591.  
  10592.  
  10593.  
  10594.  
  10595.  
  10596.  
  10597.  
  10598.  
  10599.  
  10600. Murakami & Maruyama Informational [Page 1]
  10602. RFC 2173 MAPOS June 1997
  10603.  
  10604.  
  10605. 2.1 Address Format
  10606.  
  10607. In MAPOS network, each end node has a unique HDLC address. As shown
  10608. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  10609. indicates the end of the field. When a SONET switch receives an HDLC
  10610. frame, it forwards the frame based on the address in the frame
  10611. header.
  10612.  
  10613. In unicast, MSB is 0 and the rest of the bits are the port number to
  10614. which a node is connected. Since the LSB is always 1, the minimum and
  10615. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  10616. reserved and is assigned to the control processor in a SONET switch.
  10617.  
  10618. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  10619. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  10620. indicate the group address.
  10621.  
  10622. +-------------+-+
  10623. | | | | | | | | |
  10624. | |port number|1|
  10625. +-+-----------+-+
  10626. ^ ^
  10627. | |
  10628. | +------- EA bit (always 1)
  10629. |
  10630. 1 : broadcast, multicast
  10631. 0 : unicast
  10632.  
  10633. Figure 1 Address format
  10634.  
  10635. 2.2 Address in multi-switch environment
  10636.  
  10637. In a multi-switch environment, variable-length subnet addressing is
  10638. used. Each switch has a switch number that is unique within the
  10639. system. Subnetted node addresses consist of the switch number and the
  10640. port number to which a node is connected. The address format is "0
  10641. <switch number> <node number> 1" for a unicast address, "all 1" for
  10642. the broadcast address, and "1 <group address> 1" for a multicast
  10643. address.
  10644.  
  10645. The address 0x01 is reserved and is assigned to the control processor
  10646. in the "local" switch. That is, it indicates the switch itself to
  10647. which the node is connected. The addresses of the form "0 <switch
  10648. number> <all 0> 1" are reserved, and indicates the control processor
  10649. of the switch designated by the switch number.
  10650.  
  10651. In Figure 2, the switch numbers are two bits long. Node N1 is
  10652. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  10653.  
  10654.  
  10655.  
  10656. Murakami & Maruyama Informational [Page 2]
  10658. RFC 2173 MAPOS June 1997
  10659.  
  10660.  
  10661. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  10662. has an address 01001001(0x49), since the switch number of S2 is 0x2
  10663. (10 in binary) and the port number is 0x09. Note that all the port
  10664. numbers are odd because the LSBs are always 1.
  10665.  
  10666. +------+
  10667. | node |
  10668. | N1 |
  10669. +------+
  10670. | 00100011(0x23)
  10671. |
  10672. |0x3 |0x3
  10673. +------+ +---+----+ +---+----+ +------+
  10674. | node +----+ SONET +-------+ SONET +-----+ node |
  10675. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  10676. +------+ | S1 | | S2 | +------+
  10677. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  10678. +---+----+ +---+----+
  10679. |0x7 |0x7
  10680.  
  10681.  
  10682. Figure 2 Addressing in Multiple Switch Environment
  10683.  
  10684. 4 NSP(Node-Switch Protocol)
  10685.  
  10686. This section describes the NSP protocol used for automatic node
  10687. address assignment.
  10688.  
  10689. 4.1 NSP protocol
  10690.  
  10691. NSP is introduced to provide an automatic node address assignment
  10692. function in MAPOS version 1. It reduces the administrative overhead
  10693. of node address configuration for each node and prevents troubles
  10694. such as address inconsistency and collision. When a node is connected
  10695. to a switch and receives SONET signal correctly, the node sends an
  10696. address request packet to the control processor in the local switch.
  10697. The destination address of this packet is 00000001(0x01). When the
  10698. control processor receives the packet, it replies with an address
  10699. assignment packet. The destination is the assigned node address. If
  10700. the node does not receive the address assignment packet within 5
  10701. seconds, it retransmits the address request packet. The
  10702. retransmission continues until the node successfully receives the
  10703. address assignment packet.
  10704.  
  10705. Whenever a node detects a transmission error such as carrier loss or
  10706. out-of-synchronization, it SHOULD send an address request packet to
  10707. the control processor and verify its current address. In addition, a
  10708. node MUST verify its address by sending address request packets every
  10709.  
  10710.  
  10711.  
  10712. Murakami & Maruyama Informational [Page 3]
  10714. RFC 2173 MAPOS June 1997
  10715.  
  10716.  
  10717. 30 seconds. The switch regards them as keep-alive packets and
  10718. utilizes them to detect the node's status. If it has not received a
  10719. request packet for more than 90 seconds, it assumes that the node
  10720. went down. In addition, it also assumes the node went down when a
  10721. switch detects a SONET signal failure.
  10722.  
  10723. 4.2 Packet Format
  10724.  
  10725. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  10726. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  10727. information field contains the NSP packet as shown in Figure 3.
  10728.  
  10729.  
  10730. +-----------+------------+
  10731. I command I address I
  10732. +-----------+------------+
  10733. I<- 32bit ->I<- 32 bit ->I
  10734.  
  10735. Figure 3 NSP packet format
  10736.  
  10737. The command field is 32 bits long and has the following values (in
  10738. decimal);
  10739.  
  10740. 1 address request
  10741. 2 address assignment
  10742. 3 reject(error)
  10743.  
  10744. The length of the address field is 32bits. In address request
  10745. packets, the NSP address field SHOULD be filled with zeroes, although
  10746. the switch ignores it. In address assignment packets, the assigned
  10747. address is placed in the least significant byte of the field. The
  10748. rest of the field is padded with zeroes. When the switch can not
  10749. assign the address for some reason, the switch replies with a reject
  10750. command (the values is 3). The value of the address field is
  10751. undefined.
  10752.  
  10753. 4.3 Consideration for special cases
  10754.  
  10755. There are two special cases to consider. One is a point-to-point
  10756. connection without a switch. The other is loop-back, that is, direct
  10757. connection between the input and the output of the same port.
  10758.  
  10759. 4.3.1 point-to-point
  10760.  
  10761. In the case of a point-to-point connection shown in Figure 4, a node
  10762. sends an address request packet to the other node. The destination
  10763. address is 00000001(0x01), that is usually a control processor in a
  10764. switch. When a node receives the address request, it detects the
  10765.  
  10766.  
  10767.  
  10768. Murakami & Maruyama Informational [Page 4]
  10770. RFC 2173 MAPOS June 1997
  10771.  
  10772.  
  10773. point-to-point connection by examining both the destination address
  10774. and the command contained. Then, it MUST reply with an address
  10775. assignment packet. The assigned address MUST be 00000011(0x03). Since
  10776. both nodes send an address request to each other, both of them get
  10777. address 00000011(0x03). Since any address can be used in point-to-
  10778. point environment, there is no problem even if both of the nodes have
  10779. the same address.
  10780.  
  10781. ---- address request ----> 0x01
  10782. 0x03 <---- address assignment ----
  10783. +------+ +------+
  10784. | node +--------------------------------+ node |
  10785. +------+ +------+
  10786. 0x01 <---- address request ----
  10787. ---- address assignment ----> 0x03
  10788.  
  10789. Figure 4 Point-to-point connection
  10790.  
  10791. 4.3.2 loop-back
  10792.  
  10793. Another special case is loop-back where the output port of a node is
  10794. simply connected to its input port as shown in Figure 5. In this
  10795. case, the same mechanism as that for point-to-point can be applied
  10796. without modification. A node sends an address request packet
  10797. destined to 00000001(0x01). The node then receives the same packet.
  10798. Since the destination is 00000001(0x01), it replies with an address
  10799. assignment packet, containing the assigned address 00000011(0x03), to
  10800. the address 0000 0011(0x03). Thus, the node obtains the address
  10801. 00000011(0x03).
  10802.  
  10803. ---- address request ----> 0x01
  10804. +------+ --- address assignment --> 0x03
  10805. | +-------------->-----------------+
  10806. | node + |
  10807. | +--------------<-----------------+
  10808. +------+
  10809.  
  10810. Figure 5 Loop-back Configuration
  10811.  
  10812.  
  10813.  
  10814.  
  10815.  
  10816.  
  10817.  
  10818.  
  10819.  
  10820.  
  10821.  
  10822.  
  10823.  
  10824. Murakami & Maruyama Informational [Page 5]
  10826. RFC 2173 MAPOS June 1997
  10827.  
  10828.  
  10829. 5. Security Considerations
  10830.  
  10831. Security issues are not discussed in this memo.
  10832.  
  10833. References
  10834.  
  10835. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  10836. over SONET/SDH, Version 1," RFC-2171, June 1997.
  10837.  
  10838. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  10839. Rates (1990).
  10840.  
  10841. [3] CCITT Recommendation G.708: Network Node Interface for
  10842. Synchronous Digital Hierarchy (1990).
  10843.  
  10844. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  10845. (1990).
  10846.  
  10847. [5] American National Standard for Telecommunications - Digital
  10848. Hierarchy - Optical Interface Rates and Formats Specification,
  10849. ANSI T1.105-1991.
  10850.  
  10851. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  10852. Numbers," RFC-2172, June, 1997.
  10853.  
  10854. Acknowledgements
  10855.  
  10856. The authors would like to acknowledge the contributions and
  10857. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  10858. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  10859.  
  10860. Authors' Address
  10861.  
  10862. Ken Murakami
  10863. NTT Software Laboratories
  10864. 3-9-11, Midori-cho
  10865. Musashino-shi
  10866. Tokyo 180, Japan
  10867. E-mail: murakami@ntt-20.ecl.net
  10868.  
  10869. Mitsuru Maruyama
  10870. NTT Software Laboratories
  10871. 3-9-11, Midori-cho
  10872. Musashino-shi
  10873. Tokyo 180, Japan
  10874. E-mail: mitsuru@ntt-20.ecl.net
  10875.  
  10876.  
  10877.  
  10878.  
  10879.  
  10880. Murakami & Maruyama Informational [Page 6]
  10882.  
  10883.  
  10884.  
  10885.  
  10886.  
  10887.  
  10888.  
  10889. Network Working Group K. Murakami
  10890. Request for Comments: 2173 M. Maruyama
  10891. Category: Informational NTT Laboratories
  10892. June 1997
  10893.  
  10894.  
  10895. A MAPOS version 1 Extension - Node Switch Protocol
  10896.  
  10897. Status of this Memo
  10898.  
  10899. This memo provides information for the Internet community. This memo
  10900. does not specify an Internet standard of any kind. Distribution of
  10901. this memo is unlimited.
  10902.  
  10903. Abstract
  10904.  
  10905. This document describes a MAPOS extension, Node Switch Protocol, for
  10906. automatic node address assignment. MAPOS is a multiple access
  10907. protocol for transmission of network-protocol datagrams, encapsulated
  10908. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  10909. automates the HDLC address configuration of each node. Using NSP, a
  10910. node retrieves its HDLC address from the switch to which it is
  10911. connected.
  10912.  
  10913. 1. Introduction
  10914.  
  10915. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  10916. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  10917. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  10918. switch provides multiple access capability to each node. In MAPOS,
  10919. each node has a unique HDLC address within a switch. The address is
  10920. equivalent to the port number of the switch to which the node is
  10921. connected. This document describes an extension to MAPOS, Node
  10922. Switch Protocol, which enable automatic HDLC address assignment.
  10923. First, it explains the addressing of MAPOS. Then, it describes the
  10924. NSP protocol for automatic HDLC node address assignment.
  10925.  
  10926. 2. Node Address Format
  10927.  
  10928. This section describes MAPOS Version 1 address format in single and
  10929. multiple switch environment.
  10930.  
  10931.  
  10932.  
  10933.  
  10934.  
  10935.  
  10936.  
  10937.  
  10938.  
  10939.  
  10940. Murakami & Maruyama Informational [Page 1]
  10942. RFC 2173 MAPOS June 1997
  10943.  
  10944.  
  10945. 2.1 Address Format
  10946.  
  10947. In MAPOS network, each end node has a unique HDLC address. As shown
  10948. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  10949. indicates the end of the field. When a SONET switch receives an HDLC
  10950. frame, it forwards the frame based on the address in the frame
  10951. header.
  10952.  
  10953. In unicast, MSB is 0 and the rest of the bits are the port number to
  10954. which a node is connected. Since the LSB is always 1, the minimum and
  10955. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  10956. reserved and is assigned to the control processor in a SONET switch.
  10957.  
  10958. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  10959. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  10960. indicate the group address.
  10961.  
  10962. +-------------+-+
  10963. | | | | | | | | |
  10964. | |port number|1|
  10965. +-+-----------+-+
  10966. ^ ^
  10967. | |
  10968. | +------- EA bit (always 1)
  10969. |
  10970. 1 : broadcast, multicast
  10971. 0 : unicast
  10972.  
  10973. Figure 1 Address format
  10974.  
  10975. 2.2 Address in multi-switch environment
  10976.  
  10977. In a multi-switch environment, variable-length subnet addressing is
  10978. used. Each switch has a switch number that is unique within the
  10979. system. Subnetted node addresses consist of the switch number and the
  10980. port number to which a node is connected. The address format is "0
  10981. <switch number> <node number> 1" for a unicast address, "all 1" for
  10982. the broadcast address, and "1 <group address> 1" for a multicast
  10983. address.
  10984.  
  10985. The address 0x01 is reserved and is assigned to the control processor
  10986. in the "local" switch. That is, it indicates the switch itself to
  10987. which the node is connected. The addresses of the form "0 <switch
  10988. number> <all 0> 1" are reserved, and indicates the control processor
  10989. of the switch designated by the switch number.
  10990.  
  10991. In Figure 2, the switch numbers are two bits long. Node N1 is
  10992. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  10993.  
  10994.  
  10995.  
  10996. Murakami & Maruyama Informational [Page 2]
  10998. RFC 2173 MAPOS June 1997
  10999.  
  11000.  
  11001. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  11002. has an address 01001001(0x49), since the switch number of S2 is 0x2
  11003. (10 in binary) and the port number is 0x09. Note that all the port
  11004. numbers are odd because the LSBs are always 1.
  11005.  
  11006. +------+
  11007. | node |
  11008. | N1 |
  11009. +------+
  11010. | 00100011(0x23)
  11011. |
  11012. |0x3 |0x3
  11013. +------+ +---+----+ +---+----+ +------+
  11014. | node +----+ SONET +-------+ SONET +-----+ node |
  11015. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  11016. +------+ | S1 | | S2 | +------+
  11017. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  11018. +---+----+ +---+----+
  11019. |0x7 |0x7
  11020.  
  11021.  
  11022. Figure 2 Addressing in Multiple Switch Environment
  11023.  
  11024. 4 NSP(Node-Switch Protocol)
  11025.  
  11026. This section describes the NSP protocol used for automatic node
  11027. address assignment.
  11028.  
  11029. 4.1 NSP protocol
  11030.  
  11031. NSP is introduced to provide an automatic node address assignment
  11032. function in MAPOS version 1. It reduces the administrative overhead
  11033. of node address configuration for each node and prevents troubles
  11034. such as address inconsistency and collision. When a node is connected
  11035. to a switch and receives SONET signal correctly, the node sends an
  11036. address request packet to the control processor in the local switch.
  11037. The destination address of this packet is 00000001(0x01). When the
  11038. control processor receives the packet, it replies with an address
  11039. assignment packet. The destination is the assigned node address. If
  11040. the node does not receive the address assignment packet within 5
  11041. seconds, it retransmits the address request packet. The
  11042. retransmission continues until the node successfully receives the
  11043. address assignment packet.
  11044.  
  11045. Whenever a node detects a transmission error such as carrier loss or
  11046. out-of-synchronization, it SHOULD send an address request packet to
  11047. the control processor and verify its current address. In addition, a
  11048. node MUST verify its address by sending address request packets every
  11049.  
  11050.  
  11051.  
  11052. Murakami & Maruyama Informational [Page 3]
  11054. RFC 2173 MAPOS June 1997
  11055.  
  11056.  
  11057. 30 seconds. The switch regards them as keep-alive packets and
  11058. utilizes them to detect the node's status. If it has not received a
  11059. request packet for more than 90 seconds, it assumes that the node
  11060. went down. In addition, it also assumes the node went down when a
  11061. switch detects a SONET signal failure.
  11062.  
  11063. 4.2 Packet Format
  11064.  
  11065. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  11066. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  11067. information field contains the NSP packet as shown in Figure 3.
  11068.  
  11069.  
  11070. +-----------+------------+
  11071. I command I address I
  11072. +-----------+------------+
  11073. I<- 32bit ->I<- 32 bit ->I
  11074.  
  11075. Figure 3 NSP packet format
  11076.  
  11077. The command field is 32 bits long and has the following values (in
  11078. decimal);
  11079.  
  11080. 1 address request
  11081. 2 address assignment
  11082. 3 reject(error)
  11083.  
  11084. The length of the address field is 32bits. In address request
  11085. packets, the NSP address field SHOULD be filled with zeroes, although
  11086. the switch ignores it. In address assignment packets, the assigned
  11087. address is placed in the least significant byte of the field. The
  11088. rest of the field is padded with zeroes. When the switch can not
  11089. assign the address for some reason, the switch replies with a reject
  11090. command (the values is 3). The value of the address field is
  11091. undefined.
  11092.  
  11093. 4.3 Consideration for special cases
  11094.  
  11095. There are two special cases to consider. One is a point-to-point
  11096. connection without a switch. The other is loop-back, that is, direct
  11097. connection between the input and the output of the same port.
  11098.  
  11099. 4.3.1 point-to-point
  11100.  
  11101. In the case of a point-to-point connection shown in Figure 4, a node
  11102. sends an address request packet to the other node. The destination
  11103. address is 00000001(0x01), that is usually a control processor in a
  11104. switch. When a node receives the address request, it detects the
  11105.  
  11106.  
  11107.  
  11108. Murakami & Maruyama Informational [Page 4]
  11110. RFC 2173 MAPOS June 1997
  11111.  
  11112.  
  11113. point-to-point connection by examining both the destination address
  11114. and the command contained. Then, it MUST reply with an address
  11115. assignment packet. The assigned address MUST be 00000011(0x03). Since
  11116. both nodes send an address request to each other, both of them get
  11117. address 00000011(0x03). Since any address can be used in point-to-
  11118. point environment, there is no problem even if both of the nodes have
  11119. the same address.
  11120.  
  11121. ---- address request ----> 0x01
  11122. 0x03 <---- address assignment ----
  11123. +------+ +------+
  11124. | node +--------------------------------+ node |
  11125. +------+ +------+
  11126. 0x01 <---- address request ----
  11127. ---- address assignment ----> 0x03
  11128.  
  11129. Figure 4 Point-to-point connection
  11130.  
  11131. 4.3.2 loop-back
  11132.  
  11133. Another special case is loop-back where the output port of a node is
  11134. simply connected to its input port as shown in Figure 5. In this
  11135. case, the same mechanism as that for point-to-point can be applied
  11136. without modification. A node sends an address request packet
  11137. destined to 00000001(0x01). The node then receives the same packet.
  11138. Since the destination is 00000001(0x01), it replies with an address
  11139. assignment packet, containing the assigned address 00000011(0x03), to
  11140. the address 0000 0011(0x03). Thus, the node obtains the address
  11141. 00000011(0x03).
  11142.  
  11143. ---- address request ----> 0x01
  11144. +------+ --- address assignment --> 0x03
  11145. | +-------------->-----------------+
  11146. | node + |
  11147. | +--------------<-----------------+
  11148. +------+
  11149.  
  11150. Figure 5 Loop-back Configuration
  11151.  
  11152.  
  11153.  
  11154.  
  11155.  
  11156.  
  11157.  
  11158.  
  11159.  
  11160.  
  11161.  
  11162.  
  11163.  
  11164. Murakami & Maruyama Informational [Page 5]
  11166. RFC 2173 MAPOS June 1997
  11167.  
  11168.  
  11169. 5. Security Considerations
  11170.  
  11171. Security issues are not discussed in this memo.
  11172.  
  11173. References
  11174.  
  11175. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  11176. over SONET/SDH, Version 1," RFC-2171, June 1997.
  11177.  
  11178. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  11179. Rates (1990).
  11180.  
  11181. [3] CCITT Recommendation G.708: Network Node Interface for
  11182. Synchronous Digital Hierarchy (1990).
  11183.  
  11184. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  11185. (1990).
  11186.  
  11187. [5] American National Standard for Telecommunications - Digital
  11188. Hierarchy - Optical Interface Rates and Formats Specification,
  11189. ANSI T1.105-1991.
  11190.  
  11191. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  11192. Numbers," RFC-2172, June, 1997.
  11193.  
  11194. Acknowledgements
  11195.  
  11196. The authors would like to acknowledge the contributions and
  11197. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  11198. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  11199.  
  11200. Authors' Address
  11201.  
  11202. Ken Murakami
  11203. NTT Software Laboratories
  11204. 3-9-11, Midori-cho
  11205. Musashino-shi
  11206. Tokyo 180, Japan
  11207. E-mail: murakami@ntt-20.ecl.net
  11208.  
  11209. Mitsuru Maruyama
  11210. NTT Software Laboratories
  11211. 3-9-11, Midori-cho
  11212. Musashino-shi
  11213. Tokyo 180, Japan
  11214. E-mail: mitsuru@ntt-20.ecl.net
  11215.  
  11216.  
  11217.  
  11218.  
  11219.  
  11220. Murakami & Maruyama Informational [Page 6]
  11222.  
  11223.  
  11224.  
  11225.  
  11226.  
  11227.  
  11228.  
  11229. Network Working Group K. Murakami
  11230. Request for Comments: 2173 M. Maruyama
  11231. Category: Informational NTT Laboratories
  11232. June 1997
  11233.  
  11234.  
  11235. A MAPOS version 1 Extension - Node Switch Protocol
  11236.  
  11237. Status of this Memo
  11238.  
  11239. This memo provides information for the Internet community. This memo
  11240. does not specify an Internet standard of any kind. Distribution of
  11241. this memo is unlimited.
  11242.  
  11243. Abstract
  11244.  
  11245. This document describes a MAPOS extension, Node Switch Protocol, for
  11246. automatic node address assignment. MAPOS is a multiple access
  11247. protocol for transmission of network-protocol datagrams, encapsulated
  11248. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  11249. automates the HDLC address configuration of each node. Using NSP, a
  11250. node retrieves its HDLC address from the switch to which it is
  11251. connected.
  11252.  
  11253. 1. Introduction
  11254.  
  11255. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  11256. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  11257. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  11258. switch provides multiple access capability to each node. In MAPOS,
  11259. each node has a unique HDLC address within a switch. The address is
  11260. equivalent to the port number of the switch to which the node is
  11261. connected. This document describes an extension to MAPOS, Node
  11262. Switch Protocol, which enable automatic HDLC address assignment.
  11263. First, it explains the addressing of MAPOS. Then, it describes the
  11264. NSP protocol for automatic HDLC node address assignment.
  11265.  
  11266. 2. Node Address Format
  11267.  
  11268. This section describes MAPOS Version 1 address format in single and
  11269. multiple switch environment.
  11270.  
  11271.  
  11272.  
  11273.  
  11274.  
  11275.  
  11276.  
  11277.  
  11278.  
  11279.  
  11280. Murakami & Maruyama Informational [Page 1]
  11282. RFC 2173 MAPOS June 1997
  11283.  
  11284.  
  11285. 2.1 Address Format
  11286.  
  11287. In MAPOS network, each end node has a unique HDLC address. As shown
  11288. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  11289. indicates the end of the field. When a SONET switch receives an HDLC
  11290. frame, it forwards the frame based on the address in the frame
  11291. header.
  11292.  
  11293. In unicast, MSB is 0 and the rest of the bits are the port number to
  11294. which a node is connected. Since the LSB is always 1, the minimum and
  11295. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  11296. reserved and is assigned to the control processor in a SONET switch.
  11297.  
  11298. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  11299. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  11300. indicate the group address.
  11301.  
  11302. +-------------+-+
  11303. | | | | | | | | |
  11304. | |port number|1|
  11305. +-+-----------+-+
  11306. ^ ^
  11307. | |
  11308. | +------- EA bit (always 1)
  11309. |
  11310. 1 : broadcast, multicast
  11311. 0 : unicast
  11312.  
  11313. Figure 1 Address format
  11314.  
  11315. 2.2 Address in multi-switch environment
  11316.  
  11317. In a multi-switch environment, variable-length subnet addressing is
  11318. used. Each switch has a switch number that is unique within the
  11319. system. Subnetted node addresses consist of the switch number and the
  11320. port number to which a node is connected. The address format is "0
  11321. <switch number> <node number> 1" for a unicast address, "all 1" for
  11322. the broadcast address, and "1 <group address> 1" for a multicast
  11323. address.
  11324.  
  11325. The address 0x01 is reserved and is assigned to the control processor
  11326. in the "local" switch. That is, it indicates the switch itself to
  11327. which the node is connected. The addresses of the form "0 <switch
  11328. number> <all 0> 1" are reserved, and indicates the control processor
  11329. of the switch designated by the switch number.
  11330.  
  11331. In Figure 2, the switch numbers are two bits long. Node N1 is
  11332. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  11333.  
  11334.  
  11335.  
  11336. Murakami & Maruyama Informational [Page 2]
  11338. RFC 2173 MAPOS June 1997
  11339.  
  11340.  
  11341. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  11342. has an address 01001001(0x49), since the switch number of S2 is 0x2
  11343. (10 in binary) and the port number is 0x09. Note that all the port
  11344. numbers are odd because the LSBs are always 1.
  11345.  
  11346. +------+
  11347. | node |
  11348. | N1 |
  11349. +------+
  11350. | 00100011(0x23)
  11351. |
  11352. |0x3 |0x3
  11353. +------+ +---+----+ +---+----+ +------+
  11354. | node +----+ SONET +-------+ SONET +-----+ node |
  11355. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  11356. +------+ | S1 | | S2 | +------+
  11357. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  11358. +---+----+ +---+----+
  11359. |0x7 |0x7
  11360.  
  11361.  
  11362. Figure 2 Addressing in Multiple Switch Environment
  11363.  
  11364. 4 NSP(Node-Switch Protocol)
  11365.  
  11366. This section describes the NSP protocol used for automatic node
  11367. address assignment.
  11368.  
  11369. 4.1 NSP protocol
  11370.  
  11371. NSP is introduced to provide an automatic node address assignment
  11372. function in MAPOS version 1. It reduces the administrative overhead
  11373. of node address configuration for each node and prevents troubles
  11374. such as address inconsistency and collision. When a node is connected
  11375. to a switch and receives SONET signal correctly, the node sends an
  11376. address request packet to the control processor in the local switch.
  11377. The destination address of this packet is 00000001(0x01). When the
  11378. control processor receives the packet, it replies with an address
  11379. assignment packet. The destination is the assigned node address. If
  11380. the node does not receive the address assignment packet within 5
  11381. seconds, it retransmits the address request packet. The
  11382. retransmission continues until the node successfully receives the
  11383. address assignment packet.
  11384.  
  11385. Whenever a node detects a transmission error such as carrier loss or
  11386. out-of-synchronization, it SHOULD send an address request packet to
  11387. the control processor and verify its current address. In addition, a
  11388. node MUST verify its address by sending address request packets every
  11389.  
  11390.  
  11391.  
  11392. Murakami & Maruyama Informational [Page 3]
  11394. RFC 2173 MAPOS June 1997
  11395.  
  11396.  
  11397. 30 seconds. The switch regards them as keep-alive packets and
  11398. utilizes them to detect the node's status. If it has not received a
  11399. request packet for more than 90 seconds, it assumes that the node
  11400. went down. In addition, it also assumes the node went down when a
  11401. switch detects a SONET signal failure.
  11402.  
  11403. 4.2 Packet Format
  11404.  
  11405. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  11406. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  11407. information field contains the NSP packet as shown in Figure 3.
  11408.  
  11409.  
  11410. +-----------+------------+
  11411. I command I address I
  11412. +-----------+------------+
  11413. I<- 32bit ->I<- 32 bit ->I
  11414.  
  11415. Figure 3 NSP packet format
  11416.  
  11417. The command field is 32 bits long and has the following values (in
  11418. decimal);
  11419.  
  11420. 1 address request
  11421. 2 address assignment
  11422. 3 reject(error)
  11423.  
  11424. The length of the address field is 32bits. In address request
  11425. packets, the NSP address field SHOULD be filled with zeroes, although
  11426. the switch ignores it. In address assignment packets, the assigned
  11427. address is placed in the least significant byte of the field. The
  11428. rest of the field is padded with zeroes. When the switch can not
  11429. assign the address for some reason, the switch replies with a reject
  11430. command (the values is 3). The value of the address field is
  11431. undefined.
  11432.  
  11433. 4.3 Consideration for special cases
  11434.  
  11435. There are two special cases to consider. One is a point-to-point
  11436. connection without a switch. The other is loop-back, that is, direct
  11437. connection between the input and the output of the same port.
  11438.  
  11439. 4.3.1 point-to-point
  11440.  
  11441. In the case of a point-to-point connection shown in Figure 4, a node
  11442. sends an address request packet to the other node. The destination
  11443. address is 00000001(0x01), that is usually a control processor in a
  11444. switch. When a node receives the address request, it detects the
  11445.  
  11446.  
  11447.  
  11448. Murakami & Maruyama Informational [Page 4]
  11450. RFC 2173 MAPOS June 1997
  11451.  
  11452.  
  11453. point-to-point connection by examining both the destination address
  11454. and the command contained. Then, it MUST reply with an address
  11455. assignment packet. The assigned address MUST be 00000011(0x03). Since
  11456. both nodes send an address request to each other, both of them get
  11457. address 00000011(0x03). Since any address can be used in point-to-
  11458. point environment, there is no problem even if both of the nodes have
  11459. the same address.
  11460.  
  11461. ---- address request ----> 0x01
  11462. 0x03 <---- address assignment ----
  11463. +------+ +------+
  11464. | node +--------------------------------+ node |
  11465. +------+ +------+
  11466. 0x01 <---- address request ----
  11467. ---- address assignment ----> 0x03
  11468.  
  11469. Figure 4 Point-to-point connection
  11470.  
  11471. 4.3.2 loop-back
  11472.  
  11473. Another special case is loop-back where the output port of a node is
  11474. simply connected to its input port as shown in Figure 5. In this
  11475. case, the same mechanism as that for point-to-point can be applied
  11476. without modification. A node sends an address request packet
  11477. destined to 00000001(0x01). The node then receives the same packet.
  11478. Since the destination is 00000001(0x01), it replies with an address
  11479. assignment packet, containing the assigned address 00000011(0x03), to
  11480. the address 0000 0011(0x03). Thus, the node obtains the address
  11481. 00000011(0x03).
  11482.  
  11483. ---- address request ----> 0x01
  11484. +------+ --- address assignment --> 0x03
  11485. | +-------------->-----------------+
  11486. | node + |
  11487. | +--------------<-----------------+
  11488. +------+
  11489.  
  11490. Figure 5 Loop-back Configuration
  11491.  
  11492.  
  11493.  
  11494.  
  11495.  
  11496.  
  11497.  
  11498.  
  11499.  
  11500.  
  11501.  
  11502.  
  11503.  
  11504. Murakami & Maruyama Informational [Page 5]
  11506. RFC 2173 MAPOS June 1997
  11507.  
  11508.  
  11509. 5. Security Considerations
  11510.  
  11511. Security issues are not discussed in this memo.
  11512.  
  11513. References
  11514.  
  11515. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  11516. over SONET/SDH, Version 1," RFC-2171, June 1997.
  11517.  
  11518. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  11519. Rates (1990).
  11520.  
  11521. [3] CCITT Recommendation G.708: Network Node Interface for
  11522. Synchronous Digital Hierarchy (1990).
  11523.  
  11524. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  11525. (1990).
  11526.  
  11527. [5] American National Standard for Telecommunications - Digital
  11528. Hierarchy - Optical Interface Rates and Formats Specification,
  11529. ANSI T1.105-1991.
  11530.  
  11531. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  11532. Numbers," RFC-2172, June, 1997.
  11533.  
  11534. Acknowledgements
  11535.  
  11536. The authors would like to acknowledge the contributions and
  11537. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  11538. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  11539.  
  11540. Authors' Address
  11541.  
  11542. Ken Murakami
  11543. NTT Software Laboratories
  11544. 3-9-11, Midori-cho
  11545. Musashino-shi
  11546. Tokyo 180, Japan
  11547. E-mail: murakami@ntt-20.ecl.net
  11548.  
  11549. Mitsuru Maruyama
  11550. NTT Software Laboratories
  11551. 3-9-11, Midori-cho
  11552. Musashino-shi
  11553. Tokyo 180, Japan
  11554. E-mail: mitsuru@ntt-20.ecl.net
  11555.  
  11556.  
  11557.  
  11558.  
  11559.  
  11560. Murakami & Maruyama Informational [Page 6]
  11562.  
  11563.  
  11564.  
  11565.  
  11566.  
  11567.  
  11568.  
  11569. Network Working Group K. Murakami
  11570. Request for Comments: 2173 M. Maruyama
  11571. Category: Informational NTT Laboratories
  11572. June 1997
  11573.  
  11574.  
  11575. A MAPOS version 1 Extension - Node Switch Protocol
  11576.  
  11577. Status of this Memo
  11578.  
  11579. This memo provides information for the Internet community. This memo
  11580. does not specify an Internet standard of any kind. Distribution of
  11581. this memo is unlimited.
  11582.  
  11583. Abstract
  11584.  
  11585. This document describes a MAPOS extension, Node Switch Protocol, for
  11586. automatic node address assignment. MAPOS is a multiple access
  11587. protocol for transmission of network-protocol datagrams, encapsulated
  11588. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  11589. automates the HDLC address configuration of each node. Using NSP, a
  11590. node retrieves its HDLC address from the switch to which it is
  11591. connected.
  11592.  
  11593. 1. Introduction
  11594.  
  11595. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  11596. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  11597. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  11598. switch provides multiple access capability to each node. In MAPOS,
  11599. each node has a unique HDLC address within a switch. The address is
  11600. equivalent to the port number of the switch to which the node is
  11601. connected. This document describes an extension to MAPOS, Node
  11602. Switch Protocol, which enable automatic HDLC address assignment.
  11603. First, it explains the addressing of MAPOS. Then, it describes the
  11604. NSP protocol for automatic HDLC node address assignment.
  11605.  
  11606. 2. Node Address Format
  11607.  
  11608. This section describes MAPOS Version 1 address format in single and
  11609. multiple switch environment.
  11610.  
  11611.  
  11612.  
  11613.  
  11614.  
  11615.  
  11616.  
  11617.  
  11618.  
  11619.  
  11620. Murakami & Maruyama Informational [Page 1]
  11622. RFC 2173 MAPOS June 1997
  11623.  
  11624.  
  11625. 2.1 Address Format
  11626.  
  11627. In MAPOS network, each end node has a unique HDLC address. As shown
  11628. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  11629. indicates the end of the field. When a SONET switch receives an HDLC
  11630. frame, it forwards the frame based on the address in the frame
  11631. header.
  11632.  
  11633. In unicast, MSB is 0 and the rest of the bits are the port number to
  11634. which a node is connected. Since the LSB is always 1, the minimum and
  11635. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  11636. reserved and is assigned to the control processor in a SONET switch.
  11637.  
  11638. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  11639. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  11640. indicate the group address.
  11641.  
  11642. +-------------+-+
  11643. | | | | | | | | |
  11644. | |port number|1|
  11645. +-+-----------+-+
  11646. ^ ^
  11647. | |
  11648. | +------- EA bit (always 1)
  11649. |
  11650. 1 : broadcast, multicast
  11651. 0 : unicast
  11652.  
  11653. Figure 1 Address format
  11654.  
  11655. 2.2 Address in multi-switch environment
  11656.  
  11657. In a multi-switch environment, variable-length subnet addressing is
  11658. used. Each switch has a switch number that is unique within the
  11659. system. Subnetted node addresses consist of the switch number and the
  11660. port number to which a node is connected. The address format is "0
  11661. <switch number> <node number> 1" for a unicast address, "all 1" for
  11662. the broadcast address, and "1 <group address> 1" for a multicast
  11663. address.
  11664.  
  11665. The address 0x01 is reserved and is assigned to the control processor
  11666. in the "local" switch. That is, it indicates the switch itself to
  11667. which the node is connected. The addresses of the form "0 <switch
  11668. number> <all 0> 1" are reserved, and indicates the control processor
  11669. of the switch designated by the switch number.
  11670.  
  11671. In Figure 2, the switch numbers are two bits long. Node N1 is
  11672. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  11673.  
  11674.  
  11675.  
  11676. Murakami & Maruyama Informational [Page 2]
  11678. RFC 2173 MAPOS June 1997
  11679.  
  11680.  
  11681. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  11682. has an address 01001001(0x49), since the switch number of S2 is 0x2
  11683. (10 in binary) and the port number is 0x09. Note that all the port
  11684. numbers are odd because the LSBs are always 1.
  11685.  
  11686. +------+
  11687. | node |
  11688. | N1 |
  11689. +------+
  11690. | 00100011(0x23)
  11691. |
  11692. |0x3 |0x3
  11693. +------+ +---+----+ +---+----+ +------+
  11694. | node +----+ SONET +-------+ SONET +-----+ node |
  11695. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  11696. +------+ | S1 | | S2 | +------+
  11697. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  11698. +---+----+ +---+----+
  11699. |0x7 |0x7
  11700.  
  11701.  
  11702. Figure 2 Addressing in Multiple Switch Environment
  11703.  
  11704. 4 NSP(Node-Switch Protocol)
  11705.  
  11706. This section describes the NSP protocol used for automatic node
  11707. address assignment.
  11708.  
  11709. 4.1 NSP protocol
  11710.  
  11711. NSP is introduced to provide an automatic node address assignment
  11712. function in MAPOS version 1. It reduces the administrative overhead
  11713. of node address configuration for each node and prevents troubles
  11714. such as address inconsistency and collision. When a node is connected
  11715. to a switch and receives SONET signal correctly, the node sends an
  11716. address request packet to the control processor in the local switch.
  11717. The destination address of this packet is 00000001(0x01). When the
  11718. control processor receives the packet, it replies with an address
  11719. assignment packet. The destination is the assigned node address. If
  11720. the node does not receive the address assignment packet within 5
  11721. seconds, it retransmits the address request packet. The
  11722. retransmission continues until the node successfully receives the
  11723. address assignment packet.
  11724.  
  11725. Whenever a node detects a transmission error such as carrier loss or
  11726. out-of-synchronization, it SHOULD send an address request packet to
  11727. the control processor and verify its current address. In addition, a
  11728. node MUST verify its address by sending address request packets every
  11729.  
  11730.  
  11731.  
  11732. Murakami & Maruyama Informational [Page 3]
  11734. RFC 2173 MAPOS June 1997
  11735.  
  11736.  
  11737. 30 seconds. The switch regards them as keep-alive packets and
  11738. utilizes them to detect the node's status. If it has not received a
  11739. request packet for more than 90 seconds, it assumes that the node
  11740. went down. In addition, it also assumes the node went down when a
  11741. switch detects a SONET signal failure.
  11742.  
  11743. 4.2 Packet Format
  11744.  
  11745. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  11746. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  11747. information field contains the NSP packet as shown in Figure 3.
  11748.  
  11749.  
  11750. +-----------+------------+
  11751. I command I address I
  11752. +-----------+------------+
  11753. I<- 32bit ->I<- 32 bit ->I
  11754.  
  11755. Figure 3 NSP packet format
  11756.  
  11757. The command field is 32 bits long and has the following values (in
  11758. decimal);
  11759.  
  11760. 1 address request
  11761. 2 address assignment
  11762. 3 reject(error)
  11763.  
  11764. The length of the address field is 32bits. In address request
  11765. packets, the NSP address field SHOULD be filled with zeroes, although
  11766. the switch ignores it. In address assignment packets, the assigned
  11767. address is placed in the least significant byte of the field. The
  11768. rest of the field is padded with zeroes. When the switch can not
  11769. assign the address for some reason, the switch replies with a reject
  11770. command (the values is 3). The value of the address field is
  11771. undefined.
  11772.  
  11773. 4.3 Consideration for special cases
  11774.  
  11775. There are two special cases to consider. One is a point-to-point
  11776. connection without a switch. The other is loop-back, that is, direct
  11777. connection between the input and the output of the same port.
  11778.  
  11779. 4.3.1 point-to-point
  11780.  
  11781. In the case of a point-to-point connection shown in Figure 4, a node
  11782. sends an address request packet to the other node. The destination
  11783. address is 00000001(0x01), that is usually a control processor in a
  11784. switch. When a node receives the address request, it detects the
  11785.  
  11786.  
  11787.  
  11788. Murakami & Maruyama Informational [Page 4]
  11790. RFC 2173 MAPOS June 1997
  11791.  
  11792.  
  11793. point-to-point connection by examining both the destination address
  11794. and the command contained. Then, it MUST reply with an address
  11795. assignment packet. The assigned address MUST be 00000011(0x03). Since
  11796. both nodes send an address request to each other, both of them get
  11797. address 00000011(0x03). Since any address can be used in point-to-
  11798. point environment, there is no problem even if both of the nodes have
  11799. the same address.
  11800.  
  11801. ---- address request ----> 0x01
  11802. 0x03 <---- address assignment ----
  11803. +------+ +------+
  11804. | node +--------------------------------+ node |
  11805. +------+ +------+
  11806. 0x01 <---- address request ----
  11807. ---- address assignment ----> 0x03
  11808.  
  11809. Figure 4 Point-to-point connection
  11810.  
  11811. 4.3.2 loop-back
  11812.  
  11813. Another special case is loop-back where the output port of a node is
  11814. simply connected to its input port as shown in Figure 5. In this
  11815. case, the same mechanism as that for point-to-point can be applied
  11816. without modification. A node sends an address request packet
  11817. destined to 00000001(0x01). The node then receives the same packet.
  11818. Since the destination is 00000001(0x01), it replies with an address
  11819. assignment packet, containing the assigned address 00000011(0x03), to
  11820. the address 0000 0011(0x03). Thus, the node obtains the address
  11821. 00000011(0x03).
  11822.  
  11823. ---- address request ----> 0x01
  11824. +------+ --- address assignment --> 0x03
  11825. | +-------------->-----------------+
  11826. | node + |
  11827. | +--------------<-----------------+
  11828. +------+
  11829.  
  11830. Figure 5 Loop-back Configuration
  11831.  
  11832.  
  11833.  
  11834.  
  11835.  
  11836.  
  11837.  
  11838.  
  11839.  
  11840.  
  11841.  
  11842.  
  11843.  
  11844. Murakami & Maruyama Informational [Page 5]
  11846. RFC 2173 MAPOS June 1997
  11847.  
  11848.  
  11849. 5. Security Considerations
  11850.  
  11851. Security issues are not discussed in this memo.
  11852.  
  11853. References
  11854.  
  11855. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  11856. over SONET/SDH, Version 1," RFC-2171, June 1997.
  11857.  
  11858. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  11859. Rates (1990).
  11860.  
  11861. [3] CCITT Recommendation G.708: Network Node Interface for
  11862. Synchronous Digital Hierarchy (1990).
  11863.  
  11864. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  11865. (1990).
  11866.  
  11867. [5] American National Standard for Telecommunications - Digital
  11868. Hierarchy - Optical Interface Rates and Formats Specification,
  11869. ANSI T1.105-1991.
  11870.  
  11871. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  11872. Numbers," RFC-2172, June, 1997.
  11873.  
  11874. Acknowledgements
  11875.  
  11876. The authors would like to acknowledge the contributions and
  11877. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  11878. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  11879.  
  11880. Authors' Address
  11881.  
  11882. Ken Murakami
  11883. NTT Software Laboratories
  11884. 3-9-11, Midori-cho
  11885. Musashino-shi
  11886. Tokyo 180, Japan
  11887. E-mail: murakami@ntt-20.ecl.net
  11888.  
  11889. Mitsuru Maruyama
  11890. NTT Software Laboratories
  11891. 3-9-11, Midori-cho
  11892. Musashino-shi
  11893. Tokyo 180, Japan
  11894. E-mail: mitsuru@ntt-20.ecl.net
  11895.  
  11896.  
  11897.  
  11898.  
  11899.  
  11900. Murakami & Maruyama Informational [Page 6]
  11902.  
  11903.  
  11904.  
  11905.  
  11906.  
  11907.  
  11908.  
  11909. Network Working Group K. Murakami
  11910. Request for Comments: 2173 M. Maruyama
  11911. Category: Informational NTT Laboratories
  11912. June 1997
  11913.  
  11914.  
  11915. A MAPOS version 1 Extension - Node Switch Protocol
  11916.  
  11917. Status of this Memo
  11918.  
  11919. This memo provides information for the Internet community. This memo
  11920. does not specify an Internet standard of any kind. Distribution of
  11921. this memo is unlimited.
  11922.  
  11923. Abstract
  11924.  
  11925. This document describes a MAPOS extension, Node Switch Protocol, for
  11926. automatic node address assignment. MAPOS is a multiple access
  11927. protocol for transmission of network-protocol datagrams, encapsulated
  11928. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  11929. automates the HDLC address configuration of each node. Using NSP, a
  11930. node retrieves its HDLC address from the switch to which it is
  11931. connected.
  11932.  
  11933. 1. Introduction
  11934.  
  11935. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  11936. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  11937. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  11938. switch provides multiple access capability to each node. In MAPOS,
  11939. each node has a unique HDLC address within a switch. The address is
  11940. equivalent to the port number of the switch to which the node is
  11941. connected. This document describes an extension to MAPOS, Node
  11942. Switch Protocol, which enable automatic HDLC address assignment.
  11943. First, it explains the addressing of MAPOS. Then, it describes the
  11944. NSP protocol for automatic HDLC node address assignment.
  11945.  
  11946. 2. Node Address Format
  11947.  
  11948. This section describes MAPOS Version 1 address format in single and
  11949. multiple switch environment.
  11950.  
  11951.  
  11952.  
  11953.  
  11954.  
  11955.  
  11956.  
  11957.  
  11958.  
  11959.  
  11960. Murakami & Maruyama Informational [Page 1]
  11962. RFC 2173 MAPOS June 1997
  11963.  
  11964.  
  11965. 2.1 Address Format
  11966.  
  11967. In MAPOS network, each end node has a unique HDLC address. As shown
  11968. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  11969. indicates the end of the field. When a SONET switch receives an HDLC
  11970. frame, it forwards the frame based on the address in the frame
  11971. header.
  11972.  
  11973. In unicast, MSB is 0 and the rest of the bits are the port number to
  11974. which a node is connected. Since the LSB is always 1, the minimum and
  11975. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  11976. reserved and is assigned to the control processor in a SONET switch.
  11977.  
  11978. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  11979. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  11980. indicate the group address.
  11981.  
  11982. +-------------+-+
  11983. | | | | | | | | |
  11984. | |port number|1|
  11985. +-+-----------+-+
  11986. ^ ^
  11987. | |
  11988. | +------- EA bit (always 1)
  11989. |
  11990. 1 : broadcast, multicast
  11991. 0 : unicast
  11992.  
  11993. Figure 1 Address format
  11994.  
  11995. 2.2 Address in multi-switch environment
  11996.  
  11997. In a multi-switch environment, variable-length subnet addressing is
  11998. used. Each switch has a switch number that is unique within the
  11999. system. Subnetted node addresses consist of the switch number and the
  12000. port number to which a node is connected. The address format is "0
  12001. <switch number> <node number> 1" for a unicast address, "all 1" for
  12002. the broadcast address, and "1 <group address> 1" for a multicast
  12003. address.
  12004.  
  12005. The address 0x01 is reserved and is assigned to the control processor
  12006. in the "local" switch. That is, it indicates the switch itself to
  12007. which the node is connected. The addresses of the form "0 <switch
  12008. number> <all 0> 1" are reserved, and indicates the control processor
  12009. of the switch designated by the switch number.
  12010.  
  12011. In Figure 2, the switch numbers are two bits long. Node N1 is
  12012. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  12013.  
  12014.  
  12015.  
  12016. Murakami & Maruyama Informational [Page 2]
  12018. RFC 2173 MAPOS June 1997
  12019.  
  12020.  
  12021. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  12022. has an address 01001001(0x49), since the switch number of S2 is 0x2
  12023. (10 in binary) and the port number is 0x09. Note that all the port
  12024. numbers are odd because the LSBs are always 1.
  12025.  
  12026. +------+
  12027. | node |
  12028. | N1 |
  12029. +------+
  12030. | 00100011(0x23)
  12031. |
  12032. |0x3 |0x3
  12033. +------+ +---+----+ +---+----+ +------+
  12034. | node +----+ SONET +-------+ SONET +-----+ node |
  12035. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  12036. +------+ | S1 | | S2 | +------+
  12037. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  12038. +---+----+ +---+----+
  12039. |0x7 |0x7
  12040.  
  12041.  
  12042. Figure 2 Addressing in Multiple Switch Environment
  12043.  
  12044. 4 NSP(Node-Switch Protocol)
  12045.  
  12046. This section describes the NSP protocol used for automatic node
  12047. address assignment.
  12048.  
  12049. 4.1 NSP protocol
  12050.  
  12051. NSP is introduced to provide an automatic node address assignment
  12052. function in MAPOS version 1. It reduces the administrative overhead
  12053. of node address configuration for each node and prevents troubles
  12054. such as address inconsistency and collision. When a node is connected
  12055. to a switch and receives SONET signal correctly, the node sends an
  12056. address request packet to the control processor in the local switch.
  12057. The destination address of this packet is 00000001(0x01). When the
  12058. control processor receives the packet, it replies with an address
  12059. assignment packet. The destination is the assigned node address. If
  12060. the node does not receive the address assignment packet within 5
  12061. seconds, it retransmits the address request packet. The
  12062. retransmission continues until the node successfully receives the
  12063. address assignment packet.
  12064.  
  12065. Whenever a node detects a transmission error such as carrier loss or
  12066. out-of-synchronization, it SHOULD send an address request packet to
  12067. the control processor and verify its current address. In addition, a
  12068. node MUST verify its address by sending address request packets every
  12069.  
  12070.  
  12071.  
  12072. Murakami & Maruyama Informational [Page 3]
  12074. RFC 2173 MAPOS June 1997
  12075.  
  12076.  
  12077. 30 seconds. The switch regards them as keep-alive packets and
  12078. utilizes them to detect the node's status. If it has not received a
  12079. request packet for more than 90 seconds, it assumes that the node
  12080. went down. In addition, it also assumes the node went down when a
  12081. switch detects a SONET signal failure.
  12082.  
  12083. 4.2 Packet Format
  12084.  
  12085. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  12086. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  12087. information field contains the NSP packet as shown in Figure 3.
  12088.  
  12089.  
  12090. +-----------+------------+
  12091. I command I address I
  12092. +-----------+------------+
  12093. I<- 32bit ->I<- 32 bit ->I
  12094.  
  12095. Figure 3 NSP packet format
  12096.  
  12097. The command field is 32 bits long and has the following values (in
  12098. decimal);
  12099.  
  12100. 1 address request
  12101. 2 address assignment
  12102. 3 reject(error)
  12103.  
  12104. The length of the address field is 32bits. In address request
  12105. packets, the NSP address field SHOULD be filled with zeroes, although
  12106. the switch ignores it. In address assignment packets, the assigned
  12107. address is placed in the least significant byte of the field. The
  12108. rest of the field is padded with zeroes. When the switch can not
  12109. assign the address for some reason, the switch replies with a reject
  12110. command (the values is 3). The value of the address field is
  12111. undefined.
  12112.  
  12113. 4.3 Consideration for special cases
  12114.  
  12115. There are two special cases to consider. One is a point-to-point
  12116. connection without a switch. The other is loop-back, that is, direct
  12117. connection between the input and the output of the same port.
  12118.  
  12119. 4.3.1 point-to-point
  12120.  
  12121. In the case of a point-to-point connection shown in Figure 4, a node
  12122. sends an address request packet to the other node. The destination
  12123. address is 00000001(0x01), that is usually a control processor in a
  12124. switch. When a node receives the address request, it detects the
  12125.  
  12126.  
  12127.  
  12128. Murakami & Maruyama Informational [Page 4]
  12130. RFC 2173 MAPOS June 1997
  12131.  
  12132.  
  12133. point-to-point connection by examining both the destination address
  12134. and the command contained. Then, it MUST reply with an address
  12135. assignment packet. The assigned address MUST be 00000011(0x03). Since
  12136. both nodes send an address request to each other, both of them get
  12137. address 00000011(0x03). Since any address can be used in point-to-
  12138. point environment, there is no problem even if both of the nodes have
  12139. the same address.
  12140.  
  12141. ---- address request ----> 0x01
  12142. 0x03 <---- address assignment ----
  12143. +------+ +------+
  12144. | node +--------------------------------+ node |
  12145. +------+ +------+
  12146. 0x01 <---- address request ----
  12147. ---- address assignment ----> 0x03
  12148.  
  12149. Figure 4 Point-to-point connection
  12150.  
  12151. 4.3.2 loop-back
  12152.  
  12153. Another special case is loop-back where the output port of a node is
  12154. simply connected to its input port as shown in Figure 5. In this
  12155. case, the same mechanism as that for point-to-point can be applied
  12156. without modification. A node sends an address request packet
  12157. destined to 00000001(0x01). The node then receives the same packet.
  12158. Since the destination is 00000001(0x01), it replies with an address
  12159. assignment packet, containing the assigned address 00000011(0x03), to
  12160. the address 0000 0011(0x03). Thus, the node obtains the address
  12161. 00000011(0x03).
  12162.  
  12163. ---- address request ----> 0x01
  12164. +------+ --- address assignment --> 0x03
  12165. | +-------------->-----------------+
  12166. | node + |
  12167. | +--------------<-----------------+
  12168. +------+
  12169.  
  12170. Figure 5 Loop-back Configuration
  12171.  
  12172.  
  12173.  
  12174.  
  12175.  
  12176.  
  12177.  
  12178.  
  12179.  
  12180.  
  12181.  
  12182.  
  12183.  
  12184. Murakami & Maruyama Informational [Page 5]
  12186. RFC 2173 MAPOS June 1997
  12187.  
  12188.  
  12189. 5. Security Considerations
  12190.  
  12191. Security issues are not discussed in this memo.
  12192.  
  12193. References
  12194.  
  12195. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  12196. over SONET/SDH, Version 1," RFC-2171, June 1997.
  12197.  
  12198. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  12199. Rates (1990).
  12200.  
  12201. [3] CCITT Recommendation G.708: Network Node Interface for
  12202. Synchronous Digital Hierarchy (1990).
  12203.  
  12204. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  12205. (1990).
  12206.  
  12207. [5] American National Standard for Telecommunications - Digital
  12208. Hierarchy - Optical Interface Rates and Formats Specification,
  12209. ANSI T1.105-1991.
  12210.  
  12211. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  12212. Numbers," RFC-2172, June, 1997.
  12213.  
  12214. Acknowledgements
  12215.  
  12216. The authors would like to acknowledge the contributions and
  12217. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  12218. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  12219.  
  12220. Authors' Address
  12221.  
  12222. Ken Murakami
  12223. NTT Software Laboratories
  12224. 3-9-11, Midori-cho
  12225. Musashino-shi
  12226. Tokyo 180, Japan
  12227. E-mail: murakami@ntt-20.ecl.net
  12228.  
  12229. Mitsuru Maruyama
  12230. NTT Software Laboratories
  12231. 3-9-11, Midori-cho
  12232. Musashino-shi
  12233. Tokyo 180, Japan
  12234. E-mail: mitsuru@ntt-20.ecl.net
  12235.  
  12236.  
  12237.  
  12238.  
  12239.  
  12240. Murakami & Maruyama Informational [Page 6]
  12242.  
  12243.  
  12244.  
  12245.  
  12246.  
  12247.  
  12248.  
  12249. Network Working Group K. Murakami
  12250. Request for Comments: 2173 M. Maruyama
  12251. Category: Informational NTT Laboratories
  12252. June 1997
  12253.  
  12254.  
  12255. A MAPOS version 1 Extension - Node Switch Protocol
  12256.  
  12257. Status of this Memo
  12258.  
  12259. This memo provides information for the Internet community. This memo
  12260. does not specify an Internet standard of any kind. Distribution of
  12261. this memo is unlimited.
  12262.  
  12263. Abstract
  12264.  
  12265. This document describes a MAPOS extension, Node Switch Protocol, for
  12266. automatic node address assignment. MAPOS is a multiple access
  12267. protocol for transmission of network-protocol datagrams, encapsulated
  12268. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  12269. automates the HDLC address configuration of each node. Using NSP, a
  12270. node retrieves its HDLC address from the switch to which it is
  12271. connected.
  12272.  
  12273. 1. Introduction
  12274.  
  12275. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  12276. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  12277. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  12278. switch provides multiple access capability to each node. In MAPOS,
  12279. each node has a unique HDLC address within a switch. The address is
  12280. equivalent to the port number of the switch to which the node is
  12281. connected. This document describes an extension to MAPOS, Node
  12282. Switch Protocol, which enable automatic HDLC address assignment.
  12283. First, it explains the addressing of MAPOS. Then, it describes the
  12284. NSP protocol for automatic HDLC node address assignment.
  12285.  
  12286. 2. Node Address Format
  12287.  
  12288. This section describes MAPOS Version 1 address format in single and
  12289. multiple switch environment.
  12290.  
  12291.  
  12292.  
  12293.  
  12294.  
  12295.  
  12296.  
  12297.  
  12298.  
  12299.  
  12300. Murakami & Maruyama Informational [Page 1]
  12302. RFC 2173 MAPOS June 1997
  12303.  
  12304.  
  12305. 2.1 Address Format
  12306.  
  12307. In MAPOS network, each end node has a unique HDLC address. As shown
  12308. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  12309. indicates the end of the field. When a SONET switch receives an HDLC
  12310. frame, it forwards the frame based on the address in the frame
  12311. header.
  12312.  
  12313. In unicast, MSB is 0 and the rest of the bits are the port number to
  12314. which a node is connected. Since the LSB is always 1, the minimum and
  12315. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  12316. reserved and is assigned to the control processor in a SONET switch.
  12317.  
  12318. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  12319. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  12320. indicate the group address.
  12321.  
  12322. +-------------+-+
  12323. | | | | | | | | |
  12324. | |port number|1|
  12325. +-+-----------+-+
  12326. ^ ^
  12327. | |
  12328. | +------- EA bit (always 1)
  12329. |
  12330. 1 : broadcast, multicast
  12331. 0 : unicast
  12332.  
  12333. Figure 1 Address format
  12334.  
  12335. 2.2 Address in multi-switch environment
  12336.  
  12337. In a multi-switch environment, variable-length subnet addressing is
  12338. used. Each switch has a switch number that is unique within the
  12339. system. Subnetted node addresses consist of the switch number and the
  12340. port number to which a node is connected. The address format is "0
  12341. <switch number> <node number> 1" for a unicast address, "all 1" for
  12342. the broadcast address, and "1 <group address> 1" for a multicast
  12343. address.
  12344.  
  12345. The address 0x01 is reserved and is assigned to the control processor
  12346. in the "local" switch. That is, it indicates the switch itself to
  12347. which the node is connected. The addresses of the form "0 <switch
  12348. number> <all 0> 1" are reserved, and indicates the control processor
  12349. of the switch designated by the switch number.
  12350.  
  12351. In Figure 2, the switch numbers are two bits long. Node N1 is
  12352. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  12353.  
  12354.  
  12355.  
  12356. Murakami & Maruyama Informational [Page 2]
  12358. RFC 2173 MAPOS June 1997
  12359.  
  12360.  
  12361. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  12362. has an address 01001001(0x49), since the switch number of S2 is 0x2
  12363. (10 in binary) and the port number is 0x09. Note that all the port
  12364. numbers are odd because the LSBs are always 1.
  12365.  
  12366. +------+
  12367. | node |
  12368. | N1 |
  12369. +------+
  12370. | 00100011(0x23)
  12371. |
  12372. |0x3 |0x3
  12373. +------+ +---+----+ +---+----+ +------+
  12374. | node +----+ SONET +-------+ SONET +-----+ node |
  12375. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  12376. +------+ | S1 | | S2 | +------+
  12377. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  12378. +---+----+ +---+----+
  12379. |0x7 |0x7
  12380.  
  12381.  
  12382. Figure 2 Addressing in Multiple Switch Environment
  12383.  
  12384. 4 NSP(Node-Switch Protocol)
  12385.  
  12386. This section describes the NSP protocol used for automatic node
  12387. address assignment.
  12388.  
  12389. 4.1 NSP protocol
  12390.  
  12391. NSP is introduced to provide an automatic node address assignment
  12392. function in MAPOS version 1. It reduces the administrative overhead
  12393. of node address configuration for each node and prevents troubles
  12394. such as address inconsistency and collision. When a node is connected
  12395. to a switch and receives SONET signal correctly, the node sends an
  12396. address request packet to the control processor in the local switch.
  12397. The destination address of this packet is 00000001(0x01). When the
  12398. control processor receives the packet, it replies with an address
  12399. assignment packet. The destination is the assigned node address. If
  12400. the node does not receive the address assignment packet within 5
  12401. seconds, it retransmits the address request packet. The
  12402. retransmission continues until the node successfully receives the
  12403. address assignment packet.
  12404.  
  12405. Whenever a node detects a transmission error such as carrier loss or
  12406. out-of-synchronization, it SHOULD send an address request packet to
  12407. the control processor and verify its current address. In addition, a
  12408. node MUST verify its address by sending address request packets every
  12409.  
  12410.  
  12411.  
  12412. Murakami & Maruyama Informational [Page 3]
  12414. RFC 2173 MAPOS June 1997
  12415.  
  12416.  
  12417. 30 seconds. The switch regards them as keep-alive packets and
  12418. utilizes them to detect the node's status. If it has not received a
  12419. request packet for more than 90 seconds, it assumes that the node
  12420. went down. In addition, it also assumes the node went down when a
  12421. switch detects a SONET signal failure.
  12422.  
  12423. 4.2 Packet Format
  12424.  
  12425. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  12426. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  12427. information field contains the NSP packet as shown in Figure 3.
  12428.  
  12429.  
  12430. +-----------+------------+
  12431. I command I address I
  12432. +-----------+------------+
  12433. I<- 32bit ->I<- 32 bit ->I
  12434.  
  12435. Figure 3 NSP packet format
  12436.  
  12437. The command field is 32 bits long and has the following values (in
  12438. decimal);
  12439.  
  12440. 1 address request
  12441. 2 address assignment
  12442. 3 reject(error)
  12443.  
  12444. The length of the address field is 32bits. In address request
  12445. packets, the NSP address field SHOULD be filled with zeroes, although
  12446. the switch ignores it. In address assignment packets, the assigned
  12447. address is placed in the least significant byte of the field. The
  12448. rest of the field is padded with zeroes. When the switch can not
  12449. assign the address for some reason, the switch replies with a reject
  12450. command (the values is 3). The value of the address field is
  12451. undefined.
  12452.  
  12453. 4.3 Consideration for special cases
  12454.  
  12455. There are two special cases to consider. One is a point-to-point
  12456. connection without a switch. The other is loop-back, that is, direct
  12457. connection between the input and the output of the same port.
  12458.  
  12459. 4.3.1 point-to-point
  12460.  
  12461. In the case of a point-to-point connection shown in Figure 4, a node
  12462. sends an address request packet to the other node. The destination
  12463. address is 00000001(0x01), that is usually a control processor in a
  12464. switch. When a node receives the address request, it detects the
  12465.  
  12466.  
  12467.  
  12468. Murakami & Maruyama Informational [Page 4]
  12470. RFC 2173 MAPOS June 1997
  12471.  
  12472.  
  12473. point-to-point connection by examining both the destination address
  12474. and the command contained. Then, it MUST reply with an address
  12475. assignment packet. The assigned address MUST be 00000011(0x03). Since
  12476. both nodes send an address request to each other, both of them get
  12477. address 00000011(0x03). Since any address can be used in point-to-
  12478. point environment, there is no problem even if both of the nodes have
  12479. the same address.
  12480.  
  12481. ---- address request ----> 0x01
  12482. 0x03 <---- address assignment ----
  12483. +------+ +------+
  12484. | node +--------------------------------+ node |
  12485. +------+ +------+
  12486. 0x01 <---- address request ----
  12487. ---- address assignment ----> 0x03
  12488.  
  12489. Figure 4 Point-to-point connection
  12490.  
  12491. 4.3.2 loop-back
  12492.  
  12493. Another special case is loop-back where the output port of a node is
  12494. simply connected to its input port as shown in Figure 5. In this
  12495. case, the same mechanism as that for point-to-point can be applied
  12496. without modification. A node sends an address request packet
  12497. destined to 00000001(0x01). The node then receives the same packet.
  12498. Since the destination is 00000001(0x01), it replies with an address
  12499. assignment packet, containing the assigned address 00000011(0x03), to
  12500. the address 0000 0011(0x03). Thus, the node obtains the address
  12501. 00000011(0x03).
  12502.  
  12503. ---- address request ----> 0x01
  12504. +------+ --- address assignment --> 0x03
  12505. | +-------------->-----------------+
  12506. | node + |
  12507. | +--------------<-----------------+
  12508. +------+
  12509.  
  12510. Figure 5 Loop-back Configuration
  12511.  
  12512.  
  12513.  
  12514.  
  12515.  
  12516.  
  12517.  
  12518.  
  12519.  
  12520.  
  12521.  
  12522.  
  12523.  
  12524. Murakami & Maruyama Informational [Page 5]
  12526. RFC 2173 MAPOS June 1997
  12527.  
  12528.  
  12529. 5. Security Considerations
  12530.  
  12531. Security issues are not discussed in this memo.
  12532.  
  12533. References
  12534.  
  12535. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  12536. over SONET/SDH, Version 1," RFC-2171, June 1997.
  12537.  
  12538. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  12539. Rates (1990).
  12540.  
  12541. [3] CCITT Recommendation G.708: Network Node Interface for
  12542. Synchronous Digital Hierarchy (1990).
  12543.  
  12544. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  12545. (1990).
  12546.  
  12547. [5] American National Standard for Telecommunications - Digital
  12548. Hierarchy - Optical Interface Rates and Formats Specification,
  12549. ANSI T1.105-1991.
  12550.  
  12551. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  12552. Numbers," RFC-2172, June, 1997.
  12553.  
  12554. Acknowledgements
  12555.  
  12556. The authors would like to acknowledge the contributions and
  12557. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  12558. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  12559.  
  12560. Authors' Address
  12561.  
  12562. Ken Murakami
  12563. NTT Software Laboratories
  12564. 3-9-11, Midori-cho
  12565. Musashino-shi
  12566. Tokyo 180, Japan
  12567. E-mail: murakami@ntt-20.ecl.net
  12568.  
  12569. Mitsuru Maruyama
  12570. NTT Software Laboratories
  12571. 3-9-11, Midori-cho
  12572. Musashino-shi
  12573. Tokyo 180, Japan
  12574. E-mail: mitsuru@ntt-20.ecl.net
  12575.  
  12576.  
  12577.  
  12578.  
  12579.  
  12580. Murakami & Maruyama Informational [Page 6]
  12582.  
  12583.  
  12584.  
  12585.  
  12586.  
  12587.  
  12588.  
  12589. Network Working Group K. Murakami
  12590. Request for Comments: 2173 M. Maruyama
  12591. Category: Informational NTT Laboratories
  12592. June 1997
  12593.  
  12594.  
  12595. A MAPOS version 1 Extension - Node Switch Protocol
  12596.  
  12597. Status of this Memo
  12598.  
  12599. This memo provides information for the Internet community. This memo
  12600. does not specify an Internet standard of any kind. Distribution of
  12601. this memo is unlimited.
  12602.  
  12603. Abstract
  12604.  
  12605. This document describes a MAPOS extension, Node Switch Protocol, for
  12606. automatic node address assignment. MAPOS is a multiple access
  12607. protocol for transmission of network-protocol datagrams, encapsulated
  12608. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  12609. automates the HDLC address configuration of each node. Using NSP, a
  12610. node retrieves its HDLC address from the switch to which it is
  12611. connected.
  12612.  
  12613. 1. Introduction
  12614.  
  12615. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  12616. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  12617. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  12618. switch provides multiple access capability to each node. In MAPOS,
  12619. each node has a unique HDLC address within a switch. The address is
  12620. equivalent to the port number of the switch to which the node is
  12621. connected. This document describes an extension to MAPOS, Node
  12622. Switch Protocol, which enable automatic HDLC address assignment.
  12623. First, it explains the addressing of MAPOS. Then, it describes the
  12624. NSP protocol for automatic HDLC node address assignment.
  12625.  
  12626. 2. Node Address Format
  12627.  
  12628. This section describes MAPOS Version 1 address format in single and
  12629. multiple switch environment.
  12630.  
  12631.  
  12632.  
  12633.  
  12634.  
  12635.  
  12636.  
  12637.  
  12638.  
  12639.  
  12640. Murakami & Maruyama Informational [Page 1]
  12642. RFC 2173 MAPOS June 1997
  12643.  
  12644.  
  12645. 2.1 Address Format
  12646.  
  12647. In MAPOS network, each end node has a unique HDLC address. As shown
  12648. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  12649. indicates the end of the field. When a SONET switch receives an HDLC
  12650. frame, it forwards the frame based on the address in the frame
  12651. header.
  12652.  
  12653. In unicast, MSB is 0 and the rest of the bits are the port number to
  12654. which a node is connected. Since the LSB is always 1, the minimum and
  12655. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  12656. reserved and is assigned to the control processor in a SONET switch.
  12657.  
  12658. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  12659. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  12660. indicate the group address.
  12661.  
  12662. +-------------+-+
  12663. | | | | | | | | |
  12664. | |port number|1|
  12665. +-+-----------+-+
  12666. ^ ^
  12667. | |
  12668. | +------- EA bit (always 1)
  12669. |
  12670. 1 : broadcast, multicast
  12671. 0 : unicast
  12672.  
  12673. Figure 1 Address format
  12674.  
  12675. 2.2 Address in multi-switch environment
  12676.  
  12677. In a multi-switch environment, variable-length subnet addressing is
  12678. used. Each switch has a switch number that is unique within the
  12679. system. Subnetted node addresses consist of the switch number and the
  12680. port number to which a node is connected. The address format is "0
  12681. <switch number> <node number> 1" for a unicast address, "all 1" for
  12682. the broadcast address, and "1 <group address> 1" for a multicast
  12683. address.
  12684.  
  12685. The address 0x01 is reserved and is assigned to the control processor
  12686. in the "local" switch. That is, it indicates the switch itself to
  12687. which the node is connected. The addresses of the form "0 <switch
  12688. number> <all 0> 1" are reserved, and indicates the control processor
  12689. of the switch designated by the switch number.
  12690.  
  12691. In Figure 2, the switch numbers are two bits long. Node N1 is
  12692. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  12693.  
  12694.  
  12695.  
  12696. Murakami & Maruyama Informational [Page 2]
  12698. RFC 2173 MAPOS June 1997
  12699.  
  12700.  
  12701. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  12702. has an address 01001001(0x49), since the switch number of S2 is 0x2
  12703. (10 in binary) and the port number is 0x09. Note that all the port
  12704. numbers are odd because the LSBs are always 1.
  12705.  
  12706. +------+
  12707. | node |
  12708. | N1 |
  12709. +------+
  12710. | 00100011(0x23)
  12711. |
  12712. |0x3 |0x3
  12713. +------+ +---+----+ +---+----+ +------+
  12714. | node +----+ SONET +-------+ SONET +-----+ node |
  12715. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  12716. +------+ | S1 | | S2 | +------+
  12717. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  12718. +---+----+ +---+----+
  12719. |0x7 |0x7
  12720.  
  12721.  
  12722. Figure 2 Addressing in Multiple Switch Environment
  12723.  
  12724. 4 NSP(Node-Switch Protocol)
  12725.  
  12726. This section describes the NSP protocol used for automatic node
  12727. address assignment.
  12728.  
  12729. 4.1 NSP protocol
  12730.  
  12731. NSP is introduced to provide an automatic node address assignment
  12732. function in MAPOS version 1. It reduces the administrative overhead
  12733. of node address configuration for each node and prevents troubles
  12734. such as address inconsistency and collision. When a node is connected
  12735. to a switch and receives SONET signal correctly, the node sends an
  12736. address request packet to the control processor in the local switch.
  12737. The destination address of this packet is 00000001(0x01). When the
  12738. control processor receives the packet, it replies with an address
  12739. assignment packet. The destination is the assigned node address. If
  12740. the node does not receive the address assignment packet within 5
  12741. seconds, it retransmits the address request packet. The
  12742. retransmission continues until the node successfully receives the
  12743. address assignment packet.
  12744.  
  12745. Whenever a node detects a transmission error such as carrier loss or
  12746. out-of-synchronization, it SHOULD send an address request packet to
  12747. the control processor and verify its current address. In addition, a
  12748. node MUST verify its address by sending address request packets every
  12749.  
  12750.  
  12751.  
  12752. Murakami & Maruyama Informational [Page 3]
  12754. RFC 2173 MAPOS June 1997
  12755.  
  12756.  
  12757. 30 seconds. The switch regards them as keep-alive packets and
  12758. utilizes them to detect the node's status. If it has not received a
  12759. request packet for more than 90 seconds, it assumes that the node
  12760. went down. In addition, it also assumes the node went down when a
  12761. switch detects a SONET signal failure.
  12762.  
  12763. 4.2 Packet Format
  12764.  
  12765. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  12766. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  12767. information field contains the NSP packet as shown in Figure 3.
  12768.  
  12769.  
  12770. +-----------+------------+
  12771. I command I address I
  12772. +-----------+------------+
  12773. I<- 32bit ->I<- 32 bit ->I
  12774.  
  12775. Figure 3 NSP packet format
  12776.  
  12777. The command field is 32 bits long and has the following values (in
  12778. decimal);
  12779.  
  12780. 1 address request
  12781. 2 address assignment
  12782. 3 reject(error)
  12783.  
  12784. The length of the address field is 32bits. In address request
  12785. packets, the NSP address field SHOULD be filled with zeroes, although
  12786. the switch ignores it. In address assignment packets, the assigned
  12787. address is placed in the least significant byte of the field. The
  12788. rest of the field is padded with zeroes. When the switch can not
  12789. assign the address for some reason, the switch replies with a reject
  12790. command (the values is 3). The value of the address field is
  12791. undefined.
  12792.  
  12793. 4.3 Consideration for special cases
  12794.  
  12795. There are two special cases to consider. One is a point-to-point
  12796. connection without a switch. The other is loop-back, that is, direct
  12797. connection between the input and the output of the same port.
  12798.  
  12799. 4.3.1 point-to-point
  12800.  
  12801. In the case of a point-to-point connection shown in Figure 4, a node
  12802. sends an address request packet to the other node. The destination
  12803. address is 00000001(0x01), that is usually a control processor in a
  12804. switch. When a node receives the address request, it detects the
  12805.  
  12806.  
  12807.  
  12808. Murakami & Maruyama Informational [Page 4]
  12810. RFC 2173 MAPOS June 1997
  12811.  
  12812.  
  12813. point-to-point connection by examining both the destination address
  12814. and the command contained. Then, it MUST reply with an address
  12815. assignment packet. The assigned address MUST be 00000011(0x03). Since
  12816. both nodes send an address request to each other, both of them get
  12817. address 00000011(0x03). Since any address can be used in point-to-
  12818. point environment, there is no problem even if both of the nodes have
  12819. the same address.
  12820.  
  12821. ---- address request ----> 0x01
  12822. 0x03 <---- address assignment ----
  12823. +------+ +------+
  12824. | node +--------------------------------+ node |
  12825. +------+ +------+
  12826. 0x01 <---- address request ----
  12827. ---- address assignment ----> 0x03
  12828.  
  12829. Figure 4 Point-to-point connection
  12830.  
  12831. 4.3.2 loop-back
  12832.  
  12833. Another special case is loop-back where the output port of a node is
  12834. simply connected to its input port as shown in Figure 5. In this
  12835. case, the same mechanism as that for point-to-point can be applied
  12836. without modification. A node sends an address request packet
  12837. destined to 00000001(0x01). The node then receives the same packet.
  12838. Since the destination is 00000001(0x01), it replies with an address
  12839. assignment packet, containing the assigned address 00000011(0x03), to
  12840. the address 0000 0011(0x03). Thus, the node obtains the address
  12841. 00000011(0x03).
  12842.  
  12843. ---- address request ----> 0x01
  12844. +------+ --- address assignment --> 0x03
  12845. | +-------------->-----------------+
  12846. | node + |
  12847. | +--------------<-----------------+
  12848. +------+
  12849.  
  12850. Figure 5 Loop-back Configuration
  12851.  
  12852.  
  12853.  
  12854.  
  12855.  
  12856.  
  12857.  
  12858.  
  12859.  
  12860.  
  12861.  
  12862.  
  12863.  
  12864. Murakami & Maruyama Informational [Page 5]
  12866. RFC 2173 MAPOS June 1997
  12867.  
  12868.  
  12869. 5. Security Considerations
  12870.  
  12871. Security issues are not discussed in this memo.
  12872.  
  12873. References
  12874.  
  12875. [1] Murakami, K. and M. Maruyama, "MAPOS - Multiple Access Protocol
  12876. over SONET/SDH, Version 1," RFC-2171, June 1997.
  12877.  
  12878. [2] CCITT Recommendation G.707: Synchronous Digital Hierarchy Bit
  12879. Rates (1990).
  12880.  
  12881. [3] CCITT Recommendation G.708: Network Node Interface for
  12882. Synchronous Digital Hierarchy (1990).
  12883.  
  12884. [4] CCITT Recommendation G.709: Synchronous Multiplexing Structure
  12885. (1990).
  12886.  
  12887. [5] American National Standard for Telecommunications - Digital
  12888. Hierarchy - Optical Interface Rates and Formats Specification,
  12889. ANSI T1.105-1991.
  12890.  
  12891. [6] Maruyama, M. and K. Murakami, "MAPOS Version 1 Assigned
  12892. Numbers," RFC-2172, June, 1997.
  12893.  
  12894. Acknowledgements
  12895.  
  12896. The authors would like to acknowledge the contributions and
  12897. thoughtful suggestions of John P. Mullaney, Clark Bremer, Masayuki
  12898. Kobayashi, Paul Francis, Toshiaki Yoshida, and Takahiro Sajima.
  12899.  
  12900. Authors' Address
  12901.  
  12902. Ken Murakami
  12903. NTT Software Laboratories
  12904. 3-9-11, Midori-cho
  12905. Musashino-shi
  12906. Tokyo 180, Japan
  12907. E-mail: murakami@ntt-20.ecl.net
  12908.  
  12909. Mitsuru Maruyama
  12910. NTT Software Laboratories
  12911. 3-9-11, Midori-cho
  12912. Musashino-shi
  12913. Tokyo 180, Japan
  12914. E-mail: mitsuru@ntt-20.ecl.net
  12915.  
  12916.  
  12917.  
  12918.  
  12919.  
  12920. Murakami & Maruyama Informational [Page 6]
  12922.  
  12923.  
  12924.  
  12925.  
  12926.  
  12927.  
  12928.  
  12929. Network Working Group K. Murakami
  12930. Request for Comments: 2173 M. Maruyama
  12931. Category: Informational NTT Laboratories
  12932. June 1997
  12933.  
  12934.  
  12935. A MAPOS version 1 Extension - Node Switch Protocol
  12936.  
  12937. Status of this Memo
  12938.  
  12939. This memo provides information for the Internet community. This memo
  12940. does not specify an Internet standard of any kind. Distribution of
  12941. this memo is unlimited.
  12942.  
  12943. Abstract
  12944.  
  12945. This document describes a MAPOS extension, Node Switch Protocol, for
  12946. automatic node address assignment. MAPOS is a multiple access
  12947. protocol for transmission of network-protocol datagrams, encapsulated
  12948. in High-Level Data Link Control (HDLC) frames, over SONET/SDH. NSP
  12949. automates the HDLC address configuration of each node. Using NSP, a
  12950. node retrieves its HDLC address from the switch to which it is
  12951. connected.
  12952.  
  12953. 1. Introduction
  12954.  
  12955. MAPOS[1], Multiple Access Protocol over SONET(Synchronous Optical
  12956. Network)/SDH(Synchronous Digital Hierarchy)[2][3][4][5], is a
  12957. protocol for transmission of HDLC frames over SONET/SDH. A SONET
  12958. switch provides multiple access capability to each node. In MAPOS,
  12959. each node has a unique HDLC address within a switch. The address is
  12960. equivalent to the port number of the switch to which the node is
  12961. connected. This document describes an extension to MAPOS, Node
  12962. Switch Protocol, which enable automatic HDLC address assignment.
  12963. First, it explains the addressing of MAPOS. Then, it describes the
  12964. NSP protocol for automatic HDLC node address assignment.
  12965.  
  12966. 2. Node Address Format
  12967.  
  12968. This section describes MAPOS Version 1 address format in single and
  12969. multiple switch environment.
  12970.  
  12971.  
  12972.  
  12973.  
  12974.  
  12975.  
  12976.  
  12977.  
  12978.  
  12979.  
  12980. Murakami & Maruyama Informational [Page 1]
  12982. RFC 2173 MAPOS June 1997
  12983.  
  12984.  
  12985. 2.1 Address Format
  12986.  
  12987. In MAPOS network, each end node has a unique HDLC address. As shown
  12988. in Figure 1, the address length is 8 bits. The LSB is always 1 which
  12989. indicates the end of the field. When a SONET switch receives an HDLC
  12990. frame, it forwards the frame based on the address in the frame
  12991. header.
  12992.  
  12993. In unicast, MSB is 0 and the rest of the bits are the port number to
  12994. which a node is connected. Since the LSB is always 1, the minimum and
  12995. maximum addresses are 0x01 and 0x7F, respectively. Address 0x01 is
  12996. reserved and is assigned to the control processor in a SONET switch.
  12997.  
  12998. In broadcast, MSB is 1 and the rest of the bits are all 1s. In
  12999. multicast, MSB is 1 and the rest of the bits, except for the LSB,
  13000. indicate the group address.
  13001.  
  13002. +-------------+-+
  13003. | | | | | | | | |
  13004. | |port number|1|
  13005. +-+-----------+-+
  13006. ^ ^
  13007. | |
  13008. | +------- EA bit (always 1)
  13009. |
  13010. 1 : broadcast, multicast
  13011. 0 : unicast
  13012.  
  13013. Figure 1 Address format
  13014.  
  13015. 2.2 Address in multi-switch environment
  13016.  
  13017. In a multi-switch environment, variable-length subnet addressing is
  13018. used. Each switch has a switch number that is unique within the
  13019. system. Subnetted node addresses consist of the switch number and the
  13020. port number to which a node is connected. The address format is "0
  13021. <switch number> <node number> 1" for a unicast address, "all 1" for
  13022. the broadcast address, and "1 <group address> 1" for a multicast
  13023. address.
  13024.  
  13025. The address 0x01 is reserved and is assigned to the control processor
  13026. in the "local" switch. That is, it indicates the switch itself to
  13027. which the node is connected. The addresses of the form "0 <switch
  13028. number> <all 0> 1" are reserved, and indicates the control processor
  13029. of the switch designated by the switch number.
  13030.  
  13031. In Figure 2, the switch numbers are two bits long. Node N1 is
  13032. connected to port 0x3 of switch S1 numbered 0x1 (01 in binary). Thus,
  13033.  
  13034.  
  13035.  
  13036. Murakami & Maruyama Informational [Page 2]
  13038. RFC 2173 MAPOS June 1997
  13039.  
  13040.  
  13041. the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
  13042. has an address 01001001(0x49), since the switch number of S2 is 0x2
  13043. (10 in binary) and the port number is 0x09. Note that all the port
  13044. numbers are odd because the LSBs are always 1.
  13045.  
  13046. +------+
  13047. | node |
  13048. | N1 |
  13049. +------+
  13050. | 00100011(0x23)
  13051. |
  13052. |0x3 |0x3
  13053. +------+ +---+----+ +---+----+ +------+
  13054. | node +----+ SONET +-------+ SONET +-----+ node |
  13055. | N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
  13056. +------+ | S1 | | S2 | +------+
  13057. 00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
  13058. +---+----+ +---+----+
  13059. |0x7 |0x7
  13060.  
  13061.  
  13062. Figure 2 Addressing in Multiple Switch Environment
  13063.  
  13064. 4 NSP(Node-Switch Protocol)
  13065.  
  13066. This section describes the NSP protocol used for automatic node
  13067. address assignment.
  13068.  
  13069. 4.1 NSP protocol
  13070.  
  13071. NSP is introduced to provide an automatic node address assignment
  13072. function in MAPOS version 1. It reduces the administrative overhead
  13073. of node address configuration for each node and prevents troubles
  13074. such as address inconsistency and collision. When a node is connected
  13075. to a switch and receives SONET signal correctly, the node sends an
  13076. address request packet to the control processor in the local switch.
  13077. The destination address of this packet is 00000001(0x01). When the
  13078. control processor receives the packet, it replies with an address
  13079. assignment packet. The destination is the assigned node address. If
  13080. the node does not receive the address assignment packet within 5
  13081. seconds, it retransmits the address request packet. The
  13082. retransmission continues until the node successfully receives the
  13083. address assignment packet.
  13084.  
  13085. Whenever a node detects a transmission error such as carrier loss or
  13086. out-of-synchronization, it SHOULD send an address request packet to
  13087. the control processor and verify its current address. In addition, a
  13088. node MUST verify its address by sending address request packets every
  13089.  
  13090.  
  13091.  
  13092. Murakami & Maruyama Informational [Page 3]
  13094. RFC 2173 MAPOS June 1997
  13095.  
  13096.  
  13097. 30 seconds. The switch regards them as keep-alive packets and
  13098. utilizes them to detect the node's status. If it has not received a
  13099. request packet for more than 90 seconds, it assumes that the node
  13100. went down. In addition, it also assumes the node went down when a
  13101. switch detects a SONET signal failure.
  13102.  
  13103. 4.2 Packet Format
  13104.  
  13105. The HDLC protocol field of a NSP frame contains 0xFE03 (hexadecimal)
  13106. as defined by the "MAPOS Version 1 Assigned Numbers" [6]. The
  13107. information field contains the NSP packet as shown in Figure 3.
  13108.  
  13109.  
  13110. +-----------+------------+
  13111. I command I address I
  13112. +-----------+------------+
  13113. I<- 32bit ->I<- 32 bit ->I
  13114.  
  13115. Figure 3 NSP packet format
  13116.  
  13117. The command field is 32 bits long and has the following values (in
  13118. decimal);
  13119.  
  13120. 1 address request
  13121. 2 address assignment
  13122. 3 reject(error)
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