[182755] in North American Network Operators' Group
Re: UDP clamped on service provider links
daemon@ATHENA.MIT.EDU (Christopher Morrow)
Fri Jul 31 10:36:44 2015
X-Original-To: nanog@nanog.org
In-Reply-To: <20150731070730.7bfafbde@localhost>
Date: Fri, 31 Jul 2015 10:35:37 -0400
From: Christopher Morrow <morrowc.lists@gmail.com>
To: John Kristoff <jtk@cymru.com>
Cc: NANOG <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
On Fri, Jul 31, 2015 at 8:07 AM, John Kristoff <jtk@cymru.com> wrote:
> On Thu, 30 Jul 2015 21:18:10 -0500
> Jason Baugher <jason@thebaughers.com> wrote:
>
>> In one case, when we were having an issue with a SIP trunk, we
>> re-numbered our end to another IP in the same subnet. Same path from
>> A to Z, but the packet loss mysteriously disappeared using the new
>> IP. It sure seems like they are throttling somewhere.
>
> Not knowing how you evaluated the two paths, but if MPLS was not
> considered, it may have perhaps been due in part to ECMP behavior.
> While not ruling out UDP limits, it is plausible that the changed
> source IP address resulted in a less congested path to be chosen.
ding! this sounds like the most plausible answer... I wouldn't expect
L3 to limit udp/5060/6061/SIP traffic, as a common carrier that also
runs a SIP trunking service they:
1) probably know what SIP traffic is
2) don't want to get bitten being seen as preferring their own
network offerings over other external ones (or perhaps accidentally
impacting actual customers).
