On Sat, Jun 14, 2003 at 10:59:28AM -0500, Donald Lee wrote:
> My reading of the RFCs tells me that the 1.5.2 behavior is broken, though.

It depends. How old is the RFC about non-local packets size ?

> 
> Unless you have PMTU turned on, using an ethernet MTU out "in the internet" is
> not safe.

It should be. If the router with the low MTU link can send back an ICMP
unreachable for PMTU to work, it should as well be able to fragment the
packet (anf fragmenting big packets which don't have the DF bit set *is*
a requirement).

I guess that with the developement of pppoe for ADSL, more and more
networks don't comply with this requirement (typically because the
big -> small MTU switch happens at a non-IP device), so the requirement
of using a small MTU for non-local addresses is only a workaround for such
brocken setups.

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 24 ans d'experience feront toujours la difference
--