[6021] in North American Network Operators' Group
Re: BGP Configuration Problem
daemon@ATHENA.MIT.EDU (Jon Green)
Thu Nov 7 22:52:01 1996
To: "Michael H. Lambert" <lambert@psc.edu>
cc: nanog@merit.edu
In-reply-to: Your message of "Thu, 07 Nov 1996 22:21:15 EST."
<199611080321.WAA27997@ebola.psc.edu>
Date: Thu, 07 Nov 1996 21:34:45 -0600
From: Jon Green <jcgreen@netins.net>
On Thu, 07 Nov 1996 22:21:15 -0500, lambert@psc.edu writes:
>
>We are having a BGP configuration problem which looks trivial but is not
>working the way we expect. I'm going to throw myself on the mercy of
>the court and ask for help.
>
>There are three routers A, B and C. These are in ASa, ASb and ASc,
>respectively. B imports 10.1.64/19 from A and 10.1/16 from C. What
>we were expecting was for B's route to the /19 to be via A, just because
>this is the more specific route. However, the only route (both in the
>BGP and routing tables on B) is for the entire /16 via C.
>
>I have a hunch that what is happening is that B is saying "gee, I can
>get to the entire /16 by going through C, so why bother with A". If I'm
>not mistaken, this can be fixed by introducing local_pref for both peers.
>Could someone please comment on this?
If B is hearing the route from A, it should at least show up in the BGP
table. The behavior that you expect is what it should be doing; it
sounds to me like B is not even hearing the BGP announcement from A.
Check how you have accept policies configured on B, and how you have
announce policies configured on A, and when in doubt, call your router
vendor for help. :)
-Jon
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