R1#sh run
!
interface Loopback0
 ip address 223.1.1.1 255.255.255.0
!
interface Tunnel0
 ip address 17.13.13.1 255.255.255.0
 keepalive 10 3
 tunnel source Loopback0
 tunnel destination 222.1.1.3
!

R3#sh run | b inter
interface Loopback0
 ip address 222.1.1.3 255.255.255.0
!
interface Tunnel0
 ip address 17.13.13.3 255.255.255.0
 keepalive 10 3
 tunnel source Loopback0
 tunnel destination 223.1.1.1
!