OSPF redistributing BGP routes

Unanswered Question
Oct 1st, 2008


I have the following topology along with routing protocol listed:

ASA (ospf)--> 871W(ospf/bgp)--> 871(bgp)

My dilemma/problem/issue is this:

The 871s are peering with each other with ibgp. OSPF is running between the 871w and the ASA. When I add a loopback interface to the 871 and then add to BGP, I see that route to the loopback on my 871W, but my ASA doesn't show it.

I thought BGP will distribute routes that correspond with loopbacks. I have a network on the 871W, and it's not showing up on the ASA, but the ASA can get to it because it's a directly connected network on the 871W. I would LIKE to see my loopback addresses of the other router on the ASA. Is that even possible?

I've got "redistributing bgp subnets" under the OSPF process on the 871W. Everything is up-to-date according to bgp and ospf. This is a home network, so I don't have the configs, but I can get them if nothing jumps out.



I have this problem too.
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Giuseppe Larosa Wed, 10/01/2008 - 09:19

Hello John,

you are facing a default protection mechanism thought to avoid to overload OSPF with the iBGP routes.

By default, only EBGP-learned information is candidate to be redistributed into IGP when the redistibute bgp command is issued. The IBGP routes is not redistributed into IGP until the bgp redistribute-internal command is configured under the router bgp command. But precautions must be taken in order to avoid loops within the Autonomous System when IBGP routes are redistirbuted into IGP.



Hope to help


Richard Burts Wed, 10/01/2008 - 09:23


I believe that your issue is that you are attempting to redistribute a BGP route that it learned as an IBGP route. By default BGP does not want to redistribute INGP learned routes. You can use this command under router bgp:

bgp redistribute-internal

and it should fix your issue.




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