[58338] in North American Network Operators' Group
Re: PMTU and Broken Servers
daemon@ATHENA.MIT.EDU (Leo Bicknell)
Thu May 8 11:22:09 2003
Date: Thu, 8 May 2003 11:18:27 -0400
From: Leo Bicknell <bicknell@ufp.org>
To: nanog@merit.edu
Mail-Followup-To: nanog@merit.edu
In-Reply-To: <20030508151215.GB1248@iglou.com>
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In a message written on Thu, May 08, 2003 at 11:12:19AM -0400, Jeff McAdams=
wrote:
> An only slightly better hack would be to have the tunnel and/or firewall
> twiddle the MSS on outgoing TCP connections to compensate for the lower
> tunnel MTU. Still pretty gross, but won't have as much of an effect on
> the TCP performance.
I did leave out some details. We tried Cisco code that mucks with MSS,
and that part worked but the image had other issues for us. :(
Of course, I'm also highly annoyed that you can't raise the MTU on
a Cisco tunnel. You can raise the MTU on T1's, so you can add the
tunnel overhead, but you can't then raise the MTU of the tunnel
itself. In a couple cases we could make it so the tunnel had an
MTU of 1500 if we could change it. *sigh*
--=20
Leo Bicknell - bicknell@ufp.org - CCIE 3440
PGP keys at http://www.ufp.org/~bicknell/
Read TMBG List - tmbg-list-request@tmbg.org, www.tmbg.org
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