RINA - scott whaps at the nanog hornets nest :-)

sthaug at nethelp.no sthaug at nethelp.no
Sat Nov 6 16:57:25 CDT 2010


> > > RFC 4821 PMTUD is that "negotiation" that is "lacking".  It is there.
> > > It is deployed.  It actually works.  No more relying on someone sending
> > > the ICMP packets through in order for PMTUD to work!
> > 
> > For some value of "works". There are way too many places filtering
> > ICMP for PMTUD to work consistently. PMTUD is *not* the solution,
> > unfortunately.
> 
> I guess you missed the part about 4821 PMTUD does not rely on ICMP.
> 
> Modern PMTUD does not rely on ICMP and works even where it is filtered.

As long as the implementations are few and far between:

    https://www.psc.edu/~mathis/MTU/
    http://www.ietf.org/mail-archive/web/rrg/current/msg05816.html

the traditional ICMP-based PMTUD is what most of use face today.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no




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