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Re: [ns] thrpughtput BUG??



On Wed, 17 Jan 2001, Jacky Lee wrote:

> I found that when I traced the trace file, the total
> bytes sent indicated in the trace file was different
> to [$tcp set ndatabytes_] (total bytes sent from tcp).
> Anyone can tell me why?

1) Packet drops/reordering, leading to TCP resends.

2) Header overhead (depends on the TCP variant used; FullTcp simulates
this most accurately.)

If you snoop on data being delivered by the receiver sink to the
application (I posted a simple recv() method a while back) you should
see overall correspondence with ndatabytes_

L.

<[email protected]>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>