From: Trond Myklebust <trond.myklebust@fys.uio.no>
Subject: Re: NFS not negotiating MTU correctly?
Date: Tue, 25 May 2004 11:04:49 -0400
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To: Chris Worley <cworley@lnxi.com>
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P=E5 ty , 25/05/2004 klokka 09:18, skreiv Chris Worley:

> In grilling my switch vendor, they assure me that it's the client &
> servers job to negotiate properly fragmented packets based on the lessor
> MTU.

That sounds like a piss-poor switch to me. AFAIK all routers are
supposed to automatically fragment datagrams when forwarding between
networks that have a different MTU. Automatic MTU discovery is not part
of the IP protocol (although methods for doing so under certain
circumstances do exist).

In any case, dealing with MTUs is entirely the networking layer's job.
NFS just deals with sockets. I suggest that you check that the
ip_no_pmtu_disc sysctl is set correctly, and then check with the Linux
networking mailing list (netdev@oss.sgi.com) if there are further
problems.

Cheers,
  Trond


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