[105222] in North American Network Operators' Group
Re: Single IP routing problems through Level3
daemon@ATHENA.MIT.EDU (Matthew Kaufman)
Sun Jun 15 18:08:58 2008
Date: Sun, 15 Jun 2008 15:07:21 -0700
From: Matthew Kaufman <matthew@eeph.com>
To: nanog@nanog.org
In-Reply-To: <20080615143956.GN9702@hezmatt.org>
Reply-To: matthew@eeph.com
Errors-To: nanog-bounces@nanog.org
Matt Palmer wrote:
> A multiple-link bundle which is load balanced by source/destination pair
> with an undetected dud link? I hadn't thought of that, but it does make an
> *awful* lot of sense....
I've also seen interesting OSPF misconfigurations that resulted in a
router doing path-wise load balancing between the live link and an
unroutable destination address that went into the bit bucket.
On the Cisco boxes I was using at the time, the hallmark of
load-balancing into a dead path was that every other IP address worked,
but then every some number of addresses (12, as I remember, but I'm not
100% sure) the polarity flipped, so that whichever of odd vs even had
worked before was now the one that didn't for the next N addresses.
Artifact of the hash algorithm in use, no doubt.
Matthew Kaufman
matthew@eeph.com
http://www.matthew.at
