[153242] in North American Network Operators' Group
Re: IPv6 day and tunnels
daemon@ATHENA.MIT.EDU (Joe Maimon)
Sun Jun 3 22:06:16 2012
Date: Sun, 03 Jun 2012 22:05:40 -0400
From: Joe Maimon <jmaimon@ttec.com>
To: North American Networking and Offtopic Gripes List <nanog@nanog.org>
In-Reply-To: <4FCC11B2.2090405@ttec.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Joe Maimon wrote:
> Looks like a tunnel mtu issue. I have not as of yet traced the
> definitive culprit, who is (not) sending ICMP too big, who is (not)
> receiving them, etc.
>
The culprit is the v6 tunnel, which wanders into v4 ipsec/gre tunnels,
which means the best fix is ipv6 mtu 1280 on the tunnels, and possibly
on the hosts. PMTUD works fine, just comes up with the wrong answer.
1280, the new 1500.
> Joe
