Re: aptitude/apt-get hangs during update (plus) on IPv6
Rick Thomas a écrit :
>
> My point is that by setting your MTU to 1280, you have done *your*
> part.
By doing that you have just used a side effect of the MTU as a
workaround to hide the problem originating at the other end, for TCP
connections only. Nothing has been fixed.
> At least you can be assured that all your packets will get thru
> without fragmentation,
Setting the MTU to the minimum value does not prevent fragmentation.
Datagrams bigger that the path MTU will still need to be fragmented, and
the lower you set the MTU, the more frequently fragmentation will happen.
> If the host on the other end sets its MTU to something larger and an
> intervening router doesn't do fragmentation
IPv6 routers don't do fragmentation. Fragmentation is done by the
sending host only. Intermediate routers must only generate ICMPv6
"packet too big" messages. That is similar to IPv4 when packets have the
DF flag set. Anything that drops or ignore those ICMPv6 messages will
break the path MTU discovery.
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