Two Default Routes?

[sketterman]

Is it possible to have two default routes such as 0.0.0.0 0.0.0.0 172.19.0.3 and 0.0.0.0 0.0.0.0 172.20.0.2 ? This is for rudundancy and I would want traffic to travel over the second one only if the first one became available? I don't think this can happen, but any ideas?

[thisisshanky]

Yeah its possible. Increase the administrative distance of the second default route as follows

ip route 0.0.0.0 0.0.0.0 172.19.0.3

ip route 0.0.0.0 0.0.0.0 172.20.0.2 20

The second route has admin distance of 20, while the first one has admin distance of 1. The route with lowest admin distance is always used.Admin distance can be any value from 1 to 255.

I guess u wanted the question as "This is for rudundancy and I would want traffic to travel over the second one only if the first one became unavailable? " instead of "available" in the question.

Hope that helps

[rjackson]

You will also need to do the same thing in the other two routers. Each should have and redistribute a static route to the remote network/s. The backup should have a higher admin distance.

[sketterman]

OK. I can see that. I guess the confusing part is that this first default route is to my PIX. So, let's say the Internet link goes down and I want the traffic to go via the second default route. Technically, the 172.17.0.3 is not Unreachable, so, the traffic might never use the second default route, correct? And I wonder how this solution could work.

[thisisshanky]

You will need to run a routing protocol between the internet gateway (primary) and the router in question through the PIX to determine whether the internet link is down or not.