R2#sh run | b interface Serial1/2
interface Serial1/2
 no ip address
 ipv6 address 2005:0:1203::/64 eui-64
 ipv6 ospf 1 area 20
 clock rate 64000

ipv6 router ospf 1
 router-id 2.2.2.2
 log-adjacency-changes
 area 20 virtual-link 3.3.3.3
!
R3#sh run | b interface Loo
interface Loopback0
 no ip address
 ipv6 address 2000:3:3::/64 eui-64
 ipv6 ospf 1 area 51
!
interface Serial1/2
 no ip address
 ipv6 address 2005:0:1203::/64 eui-64
 ipv6 ospf 1 area 20
!
ipv6 router ospf 1
 router-id 3.3.3.3
 log-adjacency-changes
 area 20 virtual-link 2.2.2.2
!