I have an issue in our environement at the moment with our OSPF setup.
We have 2 edge routers with GRe over IPSec tunnels out to several remote sites. These routers are connected via our core router.
Each of the remote sites have 2 tunnels configured, 1 to each of the edge routers.
I've noticed an issue where the tunnel conection fails on on of the routers the OSPF does not re route via the other router.
What appear to happen is that Router A learns that the remote network is adjecent to one of it's local subnets (the tunnel interface) and therefore advertises that it can reach the subnet. This prevents routing from working. From Edge router B you can access the remote network but from the Core the advertised route from Router A takes precedence.
The tunnels and remote site are in a different OSPF area from the core.
The only way to resolve this is to shutdown the relevant Tunnel interface on router A then everything starts to work again.
If anyone has any ideas I'd love to hear them.
Thanks and regards