v6 cdn problems

Jeroen Massar jeroen at massar.ch
Mon Nov 10 08:17:08 UTC 2014


On 2014-11-10 09:10, Christopher Morrow wrote:
> On Mon, Nov 10, 2014 at 12:51 AM, Jeroen Massar <jeroen at massar.ch> wrote:
>> There used to be a handy ipv6 at google address for reporting things. This
>> nowadays bounces.
> 
> yes, it changed to [email protected] I think.

Thus, in case of an IPv6 issue, contacting noc at 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



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