ospf gre tunnel

Remember the gre tunnel is a logical subnet. This is connected using addressing in the real world space.

| ----tunnel  subnet---------|
|                                         |
|     |     real addresses    |     |
| __|_______________|__ |



R2#s run int tu0
Building configuration...

Current configuration : 134 bytes
!
interface Tunnel0
 ip address 7.7.21.2 255.255.255.0
 ip ospf cost 65535
 tunnel source Serial0/2
 tunnel destination 7.7.12.1
end

R1#s run int tu0
Building configuration...

Current configuration : 134 bytes
!
interface Tunnel0
 ip address 7.7.21.1 255.255.255.0
 ip ospf cost 65535
 tunnel source Serial0/3
 tunnel destination 7.7.12.2
end