Fixing MTU issues - would somebody like a 'tracepath6 from 47 different ISPs'? (Was: Test your connectivity for World IPv6 Day)

Andrew Yourtchenko ayourtch at
Tue Jun 7 11:57:48 CEST 2011

On Tue, Jun 7, 2011 at 11:46 AM, Jeroen Massar <jeroen at> wrote:
> First an insult: Folks who think that blocking ICMP is 'smart' and
> 'secure' please upgrade your brain and fix your local issue and at least
> don't block ICMP Packet Too Big, it really is needed for a proper
> functioning of the Internet.


Though sometimes it is a bit more complicated than just ICMP being blocked.
(speaking from personal experience with tracking down s/w bugs).


> This shows that a traceroute works, if enough people want though, then
> yell here on the list with a "+1" and I'll work on it tonight that I get
> a tracepath6 exposed from the PoPs that can offer it, that or option B
> would be that I set up a tunnel from each of the PoPs to one host, and
> then set an MTU of 1280 on those tunnels and allow people to get a
> result of a tracepath6 from that, that will show you if you are
> reachable from behind 47 locations in the world..... would anybody see a
> need for that?

Please please please please please.

This would be a huge help in dealing with the blackholes - more
specifically, in showing to the 3rd parties that their typical
statement "noone else complained so it's got to be your local problem"
is totally misguided.


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