R1:
interface Tunnel0
 ip address 5.0.0.1 255.0.0.0
 tunnel source FastEthernet0/0
 tunnel destination 11.0.0.2
!
!
interface FastEthernet0/0
 ip address 10.0.0.2 255.0.0.0
 duplex auto
 speed auto
!
interface FastEthernet0/1
 ip address 192.168.0.1 255.255.255.0
 duplex auto
 speed auto
!
router ospf 1
 network 192.168.0.0 0.0.0.255 area 0
 network 10.0.0.0 0.255.255.255 area 0
!
ip route 0.0.0.0 0.0.0.0 5.0.0.2

R2:
interface FastEthernet0/0
 ip address 10.0.0.1 255.0.0.0
 duplex auto
 speed auto
!
interface FastEthernet0/1
 ip address 11.0.0.1 255.0.0.0
 duplex auto
 speed auto
!
router ospf 1
 network 10.0.0.0 0.255.255.255 area 0
 network 11.0.0.0 0.255.255.255 area 0

R3:
interface Tunnel0
 ip address 5.0.0.2 255.0.0.0
 tunnel source FastEthernet0/0
 tunnel destination 10.0.0.2
!
!
interface FastEthernet0/0
 ip address 11.0.0.2 255.0.0.0
 duplex auto
 speed auto
!
interface FastEthernet0/1
 ip address 175.0.0.1 255.255.255.0
 duplex auto
 speed auto
!
router ospf 1
 network 11.0.0.0 0.255.255.255 area 0
 network 175.0.0.0 0.0.0.255 area 0
!
ip route 0.0.0.0 0.0.0.0 5.0.0.1