[175976] in North American Network Operators' Group
Re: v6 cdn problems
daemon@ATHENA.MIT.EDU (Jeroen Massar)
Mon Nov 10 03:17:32 2014
X-Original-To: nanog@nanog.org
Date: Mon, 10 Nov 2014 09:17:08 +0100
From: Jeroen Massar <jeroen@massar.ch>
To: Christopher Morrow <morrowc.lists@gmail.com>
In-Reply-To: <CAL9jLab6OM1Jae-A9V_5aKNH+jvkUGTtxQ6pjdRPWsvviu6JsQ@mail.gmail.com>
Cc: nanog list <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
On 2014-11-10 09:10, Christopher Morrow wrote:
> On Mon, Nov 10, 2014 at 12:51 AM, Jeroen Massar <jeroen@massar.ch> wrote:
>> There used to be a handy ipv6@google address for reporting things. This
>> nowadays bounces.
>
> yes, it changed to noc@ I think.
Thus, in case of an IPv6 issue, contacting noc@google.com is the right
thing to do? Good to hear that the folks there are aware of IPv6.
> and yup, damian (and a few other folk) beat the mtu issue with a cold trout.
Thanks for that.
From a message by Lorenzo:
http://lists.cluenet.de/pipermail/ipv6-ops/2014-November/010278.html
it seems Google is breaking PMTUD on purpose preferring to force the
MSS to a minimum value instead.
But the problem there is not PMTUD, but what is described in:
https://tools.ietf.org/html/draft-v6ops-jaeggli-pmtud-ecmp-problem-01
Which makes sense on a Google-scale of connections. I am not sure that
breaking PTMUD and forcing MSS is the correct answer though. Forcing MSS
is likely a good intermediary step, actually fixing the load-balancer is
a better one though.
I am now wondering if that is what is hitting Akamai too, as that would
explain the problem being seen: contacting the same IP sometimes works
and sometimes does not; which could be a result of the real endnode not
always seeing the correct ICMP and thus knowing the correct MTU.
Greets,
Jeroen
