R1:
interface Ethernet0/1
ipv6address 12::1/64
ipv6ospf 1 area 0
ipv6 route ::/0 23::5EFE:303:303
ipv6 router ospf 1
router-id 1.1.1.1
R2:
interface Loopback1
ipaddress 2.2.2.2 255.255.255.0
ipospf 1 area 0
interface Tunnel1
ipv6 address 23::/64 eui-64
ipv6ospf 1 area 0
tunnel source Loopback1
tunnel mode ipv6ip isatap
interface Ethernet0/0
ipaddress 23.1.1.2 255.255.255.0
ipospf 1 area 0
router ospf 1
ipv6 route 34::/64 Tunnel1FE80::5EFE:303:303
ipv6 route ::/0 Tunnel1
ipv6 router ospf 1
R3:
interface Loopback1
ipaddress 3.3.3.3 255.255.255.0
ipospf 1 area 0
interface Tunnel1
noip address
noip redirects
ipv6address 23::/64 eui-64
ipv6ospf 1 area 0
tunnel source Loopback1
tunnel mode ipv6ip isatap
interface Ethernet0/0
ipaddress 23.1.1.3 255.255.255.0
ipospf 1 area 0
interface Ethernet0/1
ipv6 address 34::3/64
ipv6ospf 1 area 0
router ospf 1
ipv6 route 12::/64 Tunnel1FE80::5EFE:202:202
ipv6 route ::/0 Tunnel1
ipv6 router ospf 1
R4:
interface Loopback1
noip address
ipv6address 4::1/64
ipv6ospf 1 area 0
interface Ethernet0/1
ipv6 address 34::4/64
ipv6ospf 1 area 0
ipv6 route ::/0 23::5EFE:202:202
ipv6 router ospf 1
router-id 4.4.4.4