Question of the Day 1/29/09
Posted by jrensink78 on January 29, 2009
The answer to yesterday’s question “When configuring a RIP enabled interface as a passive interface, what is the end result?” is RIP will not send updates. This is something unique to RIP. You can stop RIP from sending updates on an interface with the passive-interface command. But there aren’t any commands designed to prevent RIP from receiving and processing updates on a RIP enabled interface.
There are a few methods that you can use on a router to stop RIP from processing the updates. You could use different methods for filtering the routes. You could block RIP traffic with an access list. You could enable authentication on the interface. One other option would be to use an offset list to poison the routes (push the metric to 16+). Depending on the requirements of your lab, some options will work better than others.
kamlesh sharma said
Hi,
I would like to do it with minimum config than if I am running rip v1 on neighbor side than I will configure passive interface to accept only rip v2 and if I am running rip v2 on neighbor side than I will configure passive interface to accept/recieve v1 only
Let me know if it is doable solution
Thanks
Kamlesh
jrensink78 said
That looks like it should work as well. As it’s plain to see, there are a lot of ways to skin this cat. The important point in terms of the CCIE is being able to solve a problem in multiple ways. The way that you can come up with these different solutions on the fly is to really know how the technologies work.
In this problem, there are a number of things that all have to happen for RIP to receive the advertisement and put the routes in the routing table. You just need to choose to prevent one of those things. The catch is making sure that your solution doesn’t break any other functionality or requirements of the lab.