nanog mailing list archives

Re: MTU (was Re: ULA and RIR cost-recovery)


From: Bill Owens <owens () nysernet org>
Date: Thu, 25 Nov 2004 09:11:07 -0500


On Thu, Nov 25, 2004 at 02:05:25PM +0000, Alex Bligh wrote:
Given how pMTUd works, this speculation should be relatively easy to test
(take end point on >1500 byte MTU, run traceroute with appropriate MTU to
various points and see where fragmentation required comes back). Of course
I'd have tried this myself before posting, except, urm, I can't find a
single machine I have root on that I can get more than a hop or two from
without running into 1500 byte (or less) MTU.

I happen to have such a machine and an application that specifically tests hop-by-hop MTUs, if there are any specific 
destinations you'd like checked. It has 9k to the R&E world, and 4470 to Qwest.

Bill.


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