[112150] in North American Network Operators' Group
RE: lots of prepends
daemon@ATHENA.MIT.EDU (Paul Stewart)
Thu Feb 19 16:24:38 2009
Date: Thu, 19 Feb 2009 16:24:27 -0500
In-Reply-To: <alpine.DEB.1.10.0902192215400.16135@uplift.swm.pp.se>
From: "Paul Stewart" <pstewart@nexicomgroup.net>
To: "Mikael Abrahamsson" <swmike@swm.pp.se>,
<nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
Just seen that here too:
Feb 19 16:20:35: %BGP-6-ASPATH: Long AS path 8001 8928 20912 20912 20912
20912 20912 20912 20912 20912 20912 20912 20912 20912 20912 20912 20912
20912 20912 20912 20912 20912 20912 20912 20912 20912 20912 20912 20912
20912 20912 20912 20912 20912 20912 20912 20912 20912 20912 20912 20912
20912 20912 20912 20912 20912 20912 20912 20912 20912 20912 20912 20912
20912 20912 20912 20912 20912 20912 20912 20912 20912 20912 20912 20912
20912 20912 20912 20912 20912 20912 20912 20912 20912 20912 20912 20912
20912 20912 20912 received from 207.99.64.25: More than configured
MAXAS-LIMIT
Our AS path limit is 100 which is way too high in my opinion but
regardless I was trying to figure out any logic in this.... I can
remember prepending one of our upstreams 4X at one point thinking that
was a bit nuts .... thankfully we don't prepend anyone these days....
Paul
-----Original Message-----
From: Mikael Abrahamsson [mailto:swmike@swm.pp.se]
Sent: Thursday, February 19, 2009 4:21 PM
To: nanog@nanog.org
Subject: lots of prepends
Today 85.119.176.0/21 was announced by AS20912 with 177 prepends. I
noticed 20912 modulo 256 is 176. AS47868 modulo 256 is 252 which matches
this mondays prepend-incident.
So, what router OS will put 20912 into a byte and thus end up with 176
in
something like "set as-path prepend last-as <no of prepends>" ? It needs
to be fixed.
Has anyone noticed any ill effects with IOS and using "bgp max-as"? Will
it just drop any prefixes with long as-paths and no other ill
operational
effects?
--
Mikael Abrahamsson email: swmike@swm.pp.se
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