[76795] in North American Network Operators' Group
Re: Smallest Transit MTU
daemon@ATHENA.MIT.EDU (Tony Rall)
Wed Dec 29 16:34:19 2004
In-Reply-To: <904C6A26-59C9-11D9-BF97-000D93B24C7A@isc.org>
To: nanog@merit.edu
From: Tony Rall <trall@almaden.ibm.com>
Date: Wed, 29 Dec 2004 13:33:44 -0800
Errors-To: owner-nanog-outgoing@merit.edu
On Wednesday, 2004-12-29 at 13:43 EST, Joe Abley <jabley@isc.org> wrote:
> However, there are a growing throng of broadband users who have PPTP or
> other encaps between them and the world,
Encapsulated traffic (vpns, etc.) is indeed what I see as the largest
contributor to connectivity problems for large packets.
> and who are able to get along
> just fine by reducing the advertised MSS in their TCP stack.
But that only affects tcp traffic - it does nothing to help other
protocols. In other words, it's a fairly lame circumvention that happens
to do the job for most usage (but assuming it solves the problem often
results in seemingly inexplicable failures when other protocols happen to
be used).
The better solution is to ensure that PMTUD works correctly for your
network, and get on the case of any correspondent or provider for which it
doesn't.
Tony Rall
