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New Member

Route-Reflectors and Default Gateways

I've got about 20 access routers that home back to 2 distribution routers.

Rather than fully mesh, I'm doing route-reflection on the distribution layer.

Everything is working fine, except that I have alot of BGP routes at the access-layer that point up to the distribution layer, along with default routes to the same two routers.

All the route-reflector-clients are in the same subnet, so reflected routes from the clients can be directly reached without needing to bounce through the reflector.

What is the best way to configure the route-reflectors and/or clients so that the only BGP routes the clients receive are those that were reflected from other clients ?

Thanks,

= K

  • Other Network Infrastructure Subjects
3 REPLIES
Gold

Re: Route-Reflectors and Default Gateways

You're trying to keep routes learned from a router from being reflected to a router on the same subnet? I'd probably do this with a community--set a community on the routes for any given subnet, and then block the reflection back out using a route map with a community list in it.

I'm not certain, though, that this is really what you want. It sounds more like you don't want the traffic to go through the hub--the routes still need to get between the route reflector clients, right? If so, you might try setting next-hop self on each of the route reflector clients, so the next hop is set all on the same subnet. BGP will install routes it learns from the reflector in the local table with the next hop set on the same subnet, which should resolve to a direct hop.

I would actually think this is already happening, since the IGP should show the next hop as being reachable through the common subnet, rather than through the reflector, unless you're setting next hop self on the reflector for some reason?

:-)

Russ.W

New Member

Re: Route-Reflectors and Default Gateways

Actually, what I wanted was for the route-reflector clients to only install routes from the other route reflector clients.

Since the topology is dual-hub and spoke, there was no point installing 90% of the IBGP routes since they were all reachable via the hubs anyways which happen to be originating a default route. In other words, the only IBGP routes that are actually useful at the access-layer are those that come from other access routers in the same subnet.

I went and configured a community list on the access-routers and then filterred the advertisements from the reflectors. It's working fine.

I just wanted to make sure there wasn't a single command I could type on the reflectors to only reflect routes between clients to save some time.

However, given that the advertisement policy was consistent throughout the access layer I was able to quickly implement the migration by creating a single script file and pasting it in to each of the 20 routers along with a soft-reconfig clear. Painless.

= K

Gold

Re: Route-Reflectors and Default Gateways

Nope--the community solution is the easiest and best you're going to get in this situation.

:-)

Russ.W

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