[c-nsp] BGP routes co-existing with different local-preference

Oliver Boehmer (oboehmer) oboehmer at cisco.com
Tue Oct 25 05:46:56 EDT 2005


Kristofer Sigurdsson <mailto:kristo at ipf.is> wrote on Tuesday, October
25, 2005 11:28 AM:

>> a BGP speaker always advertises its best path towards BGP neighbors.
>> If the best path is learned via iBGP (as your 7500 above), this path
>> is only advertised to other iBGP peers if the BGP speaker (the 7500)
>> is acting as route-reflector. This is the way BGP works..
> 
> Hmm, a very good point.  The actual problem is that it doesn't
> seem to start advertising the less preferred routes if the other
> edge router loses it's connectivity (actually: goes down).
> 
> I'm probably searching the wrong haystack here...

Possibly.. this is what you need to troubleshoot, so a "show ip bgp
<prefix>" (when iBGP path is not available) and the config would help to
diagnose this..

>> 
>> Are all your iBGP speakers fully-meshed?
> 
> Yes, they are - however, both of the edge routers
> are physically connected via point-to-point links to the
> actual backbone.  That shouldn't matter, though...

no, it doesn't matter..

	oli



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