Redistribution: Distribute Lists versus Route Maps

Unanswered Question
Aug 9th, 2007

I've been reading about distribute lists and route maps for redistribution. It looks like route maps on the whole have more options. They have more match criteria than just IP address and they can also set things whereas distribute lists can't.

At first glance they'd seem far superior but then I realised that they may have certain basic functionality missing that distribute lists can do...

With both distribute lists and route maps they can be applied to a routing protocol that is being distributed into another. But with distribute lists (and not route maps that I can see) they can be applied inbound to an interface for a routing protocol to permit or deny certain routes from coming into the router. And also outbound on an interface to stop certain routes leaving the router.

I can't see a way to block routes coming in based on the interface with route maps. Is this possible? The route map command under the routing process comes after the redistribute command so that means that all the routes have already come in and been put into the routing table and the route map is just applied when redistributing into another protocol.

Is it the case that distribute lists can permit or deny certain routes coming into a router and route maps can't?

Thanks

Pete.

I have this problem too.
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Pavel Bykov Thu, 08/09/2007 - 05:52

Well, you can match next hop interface in route-maps.

But i don't see a way how you can apply it to EIGRP routing process, like distribute list.

Although in BGP it's really easy. Since you can apply route-maps per neighbor, all the information can be filtered to the most granular level.

Peter.D.Brown Fri, 08/10/2007 - 00:50

Yes I see what you mean. Thanks for the reply. I had a play around with both route maps and distribute lists last night at home and found the following:

For routing protocol manipulation, route maps can only used on routers performing redistribution. They're applied to routes already in the routing table and can't filter routes from entering a router whereas distribute lists can be used on any router whether it's redistributing or not and can filter routes from entering the routing table.

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