Hi Rahim,

To make the answer complete:

Because route filtering works by regulating the routes that are entered into or advertised out of the route table, they have different effects on link state routing protocols than they do on distance vector protocols. A router running a distance vector protocol advertises routes based on what is in its route table. As a result, a route filter influences which routes the router advertises to its neighbors.

On the other hand, routers running link state protocols determine their routes based on information in their link state database, rather than on the advertised route entries of its neighbors. Route filters have no effect on links state advertisements or on the link state database.

HTH, please rate if it does help,

Mohammed Mahmoud.

Mohammed,

I think we can use distribute-lists with link state protocols like OSPF. The difference is, it does not filter the Link state database but the routes from entering the route table

Narayan

Hi Narayan,

You are right, i didn't mean that we can't use distribute-list with link-state protocols, i meant that it works differently.

In the case of distance vector a route filter influences which routes the router advertises to its neighbors.

On the other hand, routers running link state protocols determine their routes based on information in their link state database, rather than on the advertised route entries of its neighbors. Route filters have no effect on links state advertisements or on the link state database, meaning that it doesn't affect the link-state advertisements them self but rather filtering routes from entering the routing table.

BR,

Mohammed Mahmoud.