R2#sh run | b  tun
interface tunnel0
 ip address 24.24.24.2 255.255.255.0
 tunnel source Loopback1
 tunnel destination 4.4.4.4
!
interface Loopback1
 ip address 2.2.2.2 255.255.255.255
!
interface Serial1/2
 ip address 180.40.7.2 255.255.255.224
 ip pim sparse-dense-mode
 clock rate 64000
!
router ospf 1
 router-id 180.40.7.98
 log-adjacency-changes
 network 2.2.2.2 0.0.0.0 area 51
 network 180.40.7.2 0.0.0.0 area 51
 network 0.0.0.0 255.255.255.255 area 0
!

R3#sh run | b router
router ospf 1
 router-id 180.40.7.129
 log-adjacency-changes
 network 180.40.7.3 0.0.0.0 area 51
 network 180.40.7.129 0.0.0.0 area 51
 network 0.0.0.0 255.255.255.255 area 0
!

R4#sh run | b interface Loo
interface Loopback0
 ip address 4.4.4.4 255.255.255.0
!
interface Tunnel0
 ip address 24.24.24.4 255.255.255.0
 ip pim sparse-dense-mode
 tunnel source Loopback0
 tunnel destination 2.2.2.2
!
interface FastEthernet0/0
 ip address 180.40.7.130 255.255.255.224
 ip nat inside
 ip pim state-refresh origination-interval 88
 ip pim sparse-dense-mode
 ip igmp join-group 224.44.44.44
 ip igmp join-group 224.4.4.4
 duplex auto
 speed auto
 !
!
router ospf 1
 log-adjacency-changes
 network 4.4.4.4 0.0.0.0 area 51
 network 180.40.7.130 0.0.0.0 area 51
 network 0.0.0.0 255.255.255.255 area 0
!