8 messages in net.nether.puck.cisco-nsp[c-nsp] VRF randomly, stably install ...
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Everton da Silva MarquesJan 7, 2005 11:26 am 
Oliver Boehmer (oboehmer)Jan 7, 2005 12:33 pm 
Everton da Silva MarquesJan 7, 2005 1:20 pm 
Everton da Silva MarquesJan 7, 2005 1:23 pm 
Oliver Boehmer (oboehmer)Jan 7, 2005 1:37 pm 
Oliver Boehmer (oboehmer)Jan 7, 2005 1:39 pm 
Everton da Silva MarquesJan 7, 2005 3:14 pm 
Oliver Boehmer (oboehmer)Jan 7, 2005 6:06 pm 
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Subject:[c-nsp] VRF randomly, stably install only one from multiple route setsActions...
From:Everton da Silva Marques (ever@lab.ipaccess.diveo.net.br)
Date:Jan 7, 2005 1:20:59 pm
List:net.nether.puck.cisco-nsp

Oliver Boehmer (oboehmer) wrote:

R1, R2 and R3 represent the same IPv4 prefix(es), but from different VRFs?

Yes. I forgot to make such note.

Possibly not. VRF-C PE will compare all paths using the standard BGP decision algorithm (http://www.cisco.com/warp/public/459/25.shtml) and will import the best path into the VRF.

That's what I was afraid of, but hoped to find a way to tell the central VRF-C to import routes in that specific way.

I don't think so. For eBGP paths, we don't compare the router-id and stick with the "oldest" path. But for iBGP we can't do this and perform a deterministic decision which will, given all other attributes like localpref, as-path, igp-metric/etc. being equal, compare the router-id.

I see. Is it even technologically feasible? I wonder whether Cisco could implement an IOS option to make eBGP to behave like iBGP in that respect? Just out of curiosity.

Why do you need this? Maybe there are alternatives?

I now face a very similar scenario, where PE1 becomes unstable, stops exporting R1, central VRF-C switches to R2. Then PE1 would flap, its unstable routes R1 taking over R2. Then again, PE2 may also become unstable. Fortunately, both R1 and R2 (almost) never become unstable at the same time. The definitive fix is to stabilize those PE routers, and we've been working on this with Cisco for months, without an acceptable work-around. The scenario described in the previous mail could provide an acceptable, if temporary, stabilization method. Of course, alternative suggestions are appreciated.

Thank you, Oliver.