R2#sh run | b interface

interface Loopback1
 ip address 2.2.2.2 255.255.255.255
!
interface Tunnel0
 ip address 24.24.24.2 255.255.255.0
 ip pim sparse-dense-mode
 tunnel source Loopback1
 tunnel destination 4.4.4.4
!

R4#sh run | b int
interface Loopback0
 ip address 4.4.4.4 255.255.255.255
!
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
!
ip mroute 0.0.0.0 0.0.0.0 Tunnel0