Remove Default Route when link goes down

[h.parsons]

I have remote network connected to a central site with a T1 connection that is prone to go down. At the remote site I have a static default route pointing to the router at the central site, the problem is that when the T1 goes down it looks like I have a routing loop, when I ping the central site the ping response is: the ttl has expired in transit and a trace route show that the packet is circling in the router that has the T1 circuit.Is there a way to remove the default route when the T1 link goes down?

Thanks

[thisisshanky]

That is normal behaviour.

If youhave one only T1, you have two ways of setting up defaulr route

ip route 0.0.0.0 0.0.0.0 s0

OR

ip route 0.0.0.0 0.0.0.0 172.16.1.2

(172.16.1.2 is the HO router's wan ip address)

Either ways, if the T1 goes down, this default route should go out of the routing table. Do a show ip route to verify this.

So this router does not have any way to route packets destined to the HO's LAN, so it replies back with an ICMP response to the PC behind the remote site router's LAN, TTL expired in transit.

HTH.

[Richard Burts]

This seems to be an interesting situation with behavior not as we expect. Sankar is correct that usually a static default route pointed out a point to point interface will be withdrawn if the interhace goes down. From the description in the original post that is not happening. If the route were withdrawn the response to ping should be network unreachable not TTL expired in transit.

I wonder if the outbound interface is point to point or not. If the outbound interface were not point to point (perhaps something like Frame Relay on the physical interface) then the static route would not be withdrawn. Perhaps the origial poster could post the config of the router.

If the static default route is not being withdrawn when the interface goes down there might be a potential solution using a fairly new feature in IOS called Object Tracking. This link has information that could get you started on this:

http://www.cisco.com/en/US/products/sw/iosswrel/ps5413/products_feature_guide09186a00801d862d.html

HTH

Rick