Cisco router- routing problem

[jonks]

I have a number of cisco routers that route traffic off to a diffrent subnet.

About once a day these routers become unavailable. Our core router which has a static routes for each of this networks that sit behind the routers says that the route is inactive and the network becomes unreachable. If i reboot the cisco routers the routes in our core router become active again and traffic can be routed to the ciscos and beyond.

Does anyone know what causes the routes in our core router to be come inactive and the networks behind the ciscos unreachable.

If i add a static route to my PC then i can get to this networks therefor the routers are still alive and doing their job, but i cannot used the route on the core router.

 

[rbelt]

how about posting the routing table (show ip route) -- if you can, do this pre and post problem. Do you have other routing protocols enabled?

//rb

 

[routerman]

If the networks are reached via a static route it could be that an interface is going down, when the this happens any routes across that interface drop out of the routing table.

First thing I'd check is the interface counters (sh int), looking for interface resets, errors etc. Use clear count first to reset the values to 0, then monitor over a day or so.

You could use debug IP routing to track the event. Put a pc on the console port, set the exec timer to 0 0 and save the output to a text file. You may capture something which provides a clue to the problem. This would also indicate if the interfaces were bouncing on that router.

This can generate quite a bit of traffic, which could affect CPU usage on the router, you would need to check this before and after applying the debug using the show proc command.