nanog mailing list archives

Re: Sprint Help


From: Leo Bicknell <bicknell () ufp org>
Date: Thu, 18 Mar 2004 14:20:43 -0500

In a message written on Thu, Mar 18, 2004 at 11:08:21AM -0800, Michel Py wrote:
Leo Bicknell wrote
Your problem is right here:
14 urish-pitts-gw.centrepc.net (67.97.250.166) 100 msec *
100 msec NT in many configs defaults to a TCP Window size
of 8k, other NT and Server 2000 default to 16k.

This seems premature as a conclusion to me. If they don't have issues
with Japan where the best RTT they can get is around 130ms I don't see
why 100ms would be an issue.

Because these are theoretical maximums.  Very minor other issues
(eg some packet reordering, 5-10ms of jitter, a single lost packet
every now and then) will easily cut this in half.  130ms link at
95% of max (about the best you do on a clean link) would be 59k/sec,
a 100ms link with 10ms jitter would drop to around 50% of max, or
40k/sec, or 33% slower.

I bet setting the windows to 32k on both sides fixes his problem.

-- 
       Leo Bicknell - bicknell () ufp org - CCIE 3440
        PGP keys at http://www.ufp.org/~bicknell/
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