From: Scott Morris (swm@emanon.com)
Date: Mon Jul 17 2006 - 01:48:06 ART
Assuming that you aren't going to be able to reprogram bgp in the lab, a
couple of things pop into mind:
1. Make everything else before AS-Path selection equal. Therefore the
first difference would be the AS Path
2. Use something called the BGP Cost Community
See: http://www.cisco.com/warp/public/459/25.shtml
or
http://www.cisco.com/en/US/products/sw/iosswrel/ps1829/products_feature_guid
e09186a008053b5b6.html
That one seems to be supported in a variety of IOS releases, but is more
tied to MPLS stuff. So I would doubt that.
We can take AS path AWAY from the selection proces by using "bgp bestpath
as-path ignore", but that is a hidden command (although well documented!)
and likely won't be part of your test.
I would view it more as "avoiding" the things higher in the preference list
than "overriding" them.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of D.H.
Williams
Sent: Sunday, July 16, 2006 8:31 PM
To: ccielab@groupstudy.com
Subject: BGP selection process
Okay, I'm curious if anybody knows (or can provide a link) that explains the
different ways to override those BGP methods that are higher in the
selection process.
To leave the AS, Weight and LP.
For traffic coming in, AS-Path, and MED.
So, is there a way to only take into account AS-Path, for example (even
though it is further down the list)? Effectively ignoring the other methods
(weight, lp, which are taken into account first). Obviously I know of the
always compare med, but I was curious about possibly any other ways to
override things that are higher up in the selection process.
Thanks!
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