[Asterisk-Users] Re: UDP Fragmentation Problem

[Julio Arruda]

Tom Ivar Helbekkmo wrote:
> Bastian Schern wrote:
> 
> 
>>How I can setup Linux to handle UDP fragments?
> There's no setting up to do -- it simply handles them correctly.  Any
> IP stack has to.  The problem isn't there, but is an unfortunate
> interaction between the sender and gateway/firewalls along the way.
> 
> Julio Arruda wrote:
> 
> | But....it is quite weird they have such a small MTU. Many websites
> | that have problems with Path MTU discovery would be broken by that
> | (dumb websites, but still, way too many...).
> 
> The web sites in question aren't the problem.  Again, it's things that
> happen to the packets along the way that cause communication to fail.
..
> Modern Microsoft IP stacks do path MTU discovery by default, which
> means that the problem is often seen when accessing IIS web sites.
> But it's not "dumb websites", it's dumb firewall administrators. :-)

Humm...I've to disagree..Let me rephrase, I do agree with the despise 
for the blocking madness, and this is the actual cause for breaking 
pmtu, BUT, IMHO, a decent TCP stack should BY DEFAULT detect the PMTU 
Discovery blackhole, and fallback accordingly. That was not the default 
in MS from what I understand, maybe the fixed it ?
Stealing from someone else "be conservative in its sending behavior, and 
liberal in its receiving".