Router R1 Configuration:
conf t
service password-encryption
n 000000000000000000000000000000000000000000000000000o ip domain lookup
Hostname R1
enable secret class
line con 0
 logging synchronous
 password cisco
 login
line vty 0
 password cisco
 login
banner motd @Unauthorized Access is Prohibited!@
ipv6 unicast-routing
ipv6 router ospf 1
 router-id 1.1.1.1
 passive-interface g0/0
interface g0/0
 ip address 192.168.1.1 255.255.255.0
 ipv6 address 2001:db8:acad:a::1/64
 ipv6 address fe80::1 link-local
 interface s0/0/0
 clock rate 128000
 ip address 192.168.12.1 255.255.255.0
ipv6 address 2001:db8:acad:12::1/64
 ipv6 address fe80::1 link-local
 ipv6 ospf 1 area 0
 no shutdown
interface s0/0/1
 ip address 192.168.13.1 255.255.255.0
  ipv6 address 2001:db8:acad:13::1/64
 ipv6 address fe80::1 link-local
 ipv6 ospf 1 area 0
 no shutdown
router ospf 1
 network 192.168.1.0 0.0.0.255 area 0
 network 129.168.12.0 0.0.0.3 area 0
 network 192.168.13.0 0.0.0.3 area 0
 passive-interface g0/0
end


Router R2 Configuration:
conf t
service password-encryption
no ip domain lookup
hostname R2
enable secret class
line con 0
 logging synchronous
 password cisco
 login
line vty 0
 password cisco
 login
banner motd @Unauthorized Access is Prohibited!@
ipv6 unicast-routing
ipv6 router ospf 1
 router-id 2.2.2.2
interface g0/0
ip address 192.168.2.1 255.255.255.0
 ipv6 address 2001:db8:acad:B::2/64
 ipv6 address fe80::1 link-local
no shutdown
interface s0/0/0
 ip address 192.168.12.2 255.255.255.252
 ipv6 address 2001:db8:acad:12::2/64
 ipv6 address fe80::2 link-local
 ipv6 ospf 1 area 0
 no shutdown
interface s0/0/1
 clock rate 128000
ipv6 address 2001:db8:acad:23::2/64
 ipv6 address fe80::2 link-local
  no shutdown
router ospf 1
 network 192.168.2.0 0.0.0.255 area 0
 network 192.168.12.0 0.0.0.3 area 0
 network 192.168.23.0 0.0.0.3 area 0
 end


Router R3 Configuration:
conf t
service password-encryption
no ip domain lookup
enable secret class
hostname R3
line con 0
 logging synchronous
 password cisco
 login
line vty 0
 password cisco
 login
banner motd @Unauthorized Access is Prohibited!@
interface g0/0
ipv6 address 2001:db8:acad:c::3/64
 ipv6 address fe80::3 link-local
 interface s0/0/0
 clock rate 128000
 ip address 192.168.13.1 255.255.255.252
ipv6 address 2001:db8:acad:13::3/64
 ipv6 address fe80::3 link-local
  no shutdown
interface s0/0/1
 ip address 192.168.23.2 255.255.255.252
 ipv6 address 2001:db8:acad:23::3/64
 ipv6 address fe80::3 link-local
 router ospf 1
 network 192.168.3.0 0.0.0.255 area 0
passive-interface g0/0
end