Too bigs are sacred, was: Re: IPv6 addressing for core network

Wed Feb 9 17:50:35 UTC 2011

Iljitsch van Beijnum wrote:
> On 9 feb 2011, at 18:30, David Freedman wrote:
> 
>> (yes, even ICMP TOOBIG
>> can be filtered safely if you have designed things in a sane way)
> 
> NO.
> 
> Even if you run with 1280-byte MTUs everywhere so you'd think path MTU discovery wouldn't be needed, this can still cause problems with IPv6-to-IPv4 translators.
> 

Calm down, I think you misunderstand,

I'm suggesting that you don't design your infrastructure in such a way
that your backbone/infrastructure links ever have to receive TOOBIG
messages from outside your AS and work with these, your backbone links
are of course free to send TOOBIG out!

Dave.

-- 

David Freedman
Group Network Engineering
Claranet Group