Test your connectivity for World IPv6 Day

Marc Blanchet marc.blanchet at viagenie.ca
Tue Jun 7 14:07:13 CEST 2011

Le 11-06-07 07:55, Rémi Després a écrit :
> Le 7 juin 2011 à 13:26, Marc Blanchet a écrit :
>> Le 11-06-07 07:03, Mohacsi Janos a écrit :
>>> Dear All,
>>> A possible option would be for develop a new opportunistic PMTUD standard:
>>> - start from 1280 and increase it until it is possible....
>> see RFC4821.
> Agreed.
> However, RFC 4821 isn't completely clear as to which PMTU to try first.

I've heard that it is already implemented on linux. don't know the 
details yet.

> As detailed in my last answer to Fred, 1280 seems the best choice, at least in IPv6.
> Can we agree on this?

nooo! IPv4 typical MTU is 1500. you are suggesting downgrading IPv6 
performance (compared to IPv4) by doing MTU 1280? does not make sense to 
me. PMTUd issues are the exception, not the problem. But the level of 
exceptions are higher now than it shall be later, since we are really 
deploying IPv6 now, removing old stuff, fixing as we go.

Think also about backbone nodes/high-end servers that are able to do 9K 
MTU. Change to 1280 MTU. no.


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