[165101] in North American Network Operators' Group
Re: BGP Route Issues
daemon@ATHENA.MIT.EDU (Seth Mattinen)
Sun Aug 18 23:10:59 2013
Date: Sun, 18 Aug 2013 20:10:26 -0700
From: Seth Mattinen <sethm@rollernet.us>
To: nanog@nanog.org
In-Reply-To: <521175F3.5010505@gmail.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On 8/18/13 6:33 PM, Christopher Karel wrote:
>
> I'm hoping you guys might be able to offer some advice or insight
> into a BGP problem I've got. I've noticed some strange routes between
> our network, AS27270, and AS22943. It looks like both our networks are
> dual homed. One ISP as the primary, and the other used as a backup,
> with path prepending to prevent it from actually being used except in an
> outage. However, our route to 22943 appears to be using their backup
> link. (27270 4323 7018 22943 22943 22943 22943 22943 22943 22943 22943
> 22943 22943 22943) Which is strange, because we can reach their primary
> ISP without any such rigmarole.
It's not strange. AS path prepending like a typewriter monkey on crack
doesn't mean anything and certainly does not a "backup" link make.
Localpref can and will make it the best path anyway.
~Seth
