[154519] in North American Network Operators' Group
Re: job screening question
daemon@ATHENA.MIT.EDU (Derek Ivey)
Thu Jul 5 13:46:42 2012
From: Derek Ivey <derek@derekivey.com>
In-Reply-To: <CAP-guGVB1ut=MRhLNK+8boWLOAQoU+m_Kwd+0G_JjyVg55ftVg@mail.gmail.com>
Date: Thu, 5 Jul 2012 13:45:54 -0400
To: William Herrin <bill@herrin.us>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
This is exactly the issue comcast6.net is currently experiencing :). =
They seem to be blocking ICMP completely and that is causing my HE IPv6 =
tunnel to be unable to access their site from a browser.=20
On Jul 5, 2012, at 1:41 PM, William Herrin wrote:
> On Thu, Jul 5, 2012 at 1:20 PM, Darius Jahandarie =
<djahandarie@gmail.com> wrote:
>> On Thu, Jul 5, 2012 at 1:11 PM, Oliver Garraux <oliver@g.garraux.net> =
wrote:
>>> Seems fairly straightforward to me. It'll break path MTU discovery.
>>=20
>> Since Bill said "(not IP in general, TCP specifically)", I don't =
think
>> PMTUD breaking is what he's looking for.
>=20
> No, path MTU discovery is the answer I'm fishing for. The stack
> notifies TCP of the fragmentation needed message and TCP handles it
> within the TCP stack. Managing path MTU discovery is specific to each
> layer-4 protocol even if the trigger message (destination unreachable,
> fragmentation needed but DF set) is the same.
>=20
> If a candidate gives me a more clever answer, I'd take that too. :-)
>=20
> "This would block all IP traffic." is not a correct answer. It's not
> even a naively incorrect answer.
>=20
> Regards,
> Bill Herrin
>=20
>=20
> --=20
> William D. Herrin ................ herrin@dirtside.com bill@herrin.us
> 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
> Falls Church, VA 22042-3004
>=20
