Re: ICMP fragmentation required but DF set problems.

[Felix von Leitner <leitner () VIM ORG>]

Thus spake Mark.Andrews () NOMINUM COM (Mark.Andrews () NOMINUM COM):
> > IPv6 is another case though.  Here you have mandatory PMTU for all
> > protocols.
>       This is a myth.  It is quite possible to have a IPv6
>       implementation that does not require PMTU discovery.  You
>       just fragment all your traffic at the network MTU.  If fact
>       there are hooks in the BSD advansed API to allow you to do
>       this on a per socket basis.

That is a myth, too.
If chose not to to PMTU in IPv6, you have to limit your MTU to ~1200
byts (the exact value is in the RFC).  So it's not the network MTU you
are using.

>       DNS servers, for one, need to be able to disable PMTU on
>       the replies.

?

Felix