Sample Configuration for an IPIP tunnel. The IP addressed have been changed to protect the innocent.
interface Tunnel0 ip address 10.10.10.5 255.255.255.252 no ip directed-broadcast tunnel source 192.168.253.21 tunnel destination 111.111.2.3 tunnel mode ipip ! ip route 111.111.2.3 255.255.255.255 Serial0If you enjoyed this post, make sure you subscribe to my RSS feed!






Where possible, use GRE instead of IP-in-IP.
GRE has less overheads (as little as 4 bytes vs 20 bytes) so is leaner, and gives you more payload space to play with.
Simply “no tunnel mode ipip” or omit that line when you configure the tunnel as the default operating mode of a tunnel on a Cisco router is GRE.
However, one thing to keep in mind is that GRE is its own protocol and may be blocked by some firewalls.