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. 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.
Since Bill said "(not IP in general, TCP specifically)", I don't think PMTUD breaking is what he's looking for.
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.
If a candidate gives me a more clever answer, I'd take that too. :-)
"This would block all IP traffic." is not a correct answer. It's not even a naively incorrect answer.
Regards, Bill Herrin
-- William D. Herrin ................ herrin@dirtside.com bill@herrin.us 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/> Falls Church, VA 22042-3004