[116767] in North American Network Operators' Group
Re: Anyone else seeing "(invalid or corrupt AS path) 3 bytes E01100" ?
daemon@ATHENA.MIT.EDU (Joe Provo)
Mon Aug 17 17:49:25 2009
Date: Mon, 17 Aug 2009 17:48:40 -0400
From: Joe Provo <nanog-post@rsuc.gweep.net>
To: randal k <nanog@data102.com>
In-Reply-To: <daf895880908171437m19b7f7f8u2bda80d82a28b8b@mail.gmail.com>
Cc: nanog@nanog.org
Reply-To: nanog-post@rsuc.gweep.net
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Mon, Aug 17, 2009 at 03:37:07PM -0600, randal k wrote:
> Yep, we started seeing this right around 12:20pm MST. We saw it from a
> customer's rapidly-flapping BGP peer. We told them to configure bgp
> maxas-limit, but apparently CRS1s don't have that command.
>
> Anybody have a handy route-map that will deny anything with a as-path
> longer than say 15-20? ;-)
Been a while since I had to throw this on cisco, but I since it lacks
sane repeat constraint, you have to either choose to iterate over your
acceptable space or deny on the longer-than-acceptable. For the latter,
^[0-9]+_[0-9]+_[0-9]+_[0-9]+_[0-9]+_[0-9]+_[0-9]+_[0-9]+_[0-9]+_[0-9]+_[0-9]+_[0-9]+_[0-9]+_[0-9]+_([0-9]+_)+
clobbers 15 ASNs and longer.
--
RSUC / GweepNet / Spunk / FnB / Usenix / SAGE
