I have IPIP tunnels running between two ros 6.42.1 routers. If an internet circuit fails at a router, the tunnel goes down. However when the circuit comes back, the tunnel does not come back up.
I can ping the router from the another, and vice-versa. I tried re-enable and recreating the IPIP interface but that didn’t help. Even I tried rebooting the routers. Nothing works.
Any ideas?
How does the network between the two routers (the “internet circuit”) look like? Do both routers have a static address, and is there any NAT between them? IPIP is a port-less protocols so if several devices behind the same NAT use that protocol, the NAT can serve one of them at most if the remote end is the same (as it cannot tell one session from another as the only identifier on the public side is the IP address of the remote end and it is the same for both sessions). So if one router is behind a NAT and has received a different internet-facing address after the event, the NAT somewhere in between may still remember the old one so the IPIP tunnel only works in one direction or not at all.