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Ethereal-users: Re: [Ethereal-users] TCP performance measurment in csv format

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From: "Ronnie Sahlberg" <ronnie_sahlberg@xxxxxxxxxxxxxx>
Date: Tue, 1 Apr 2003 19:15:42 +1000
You should be able to do some tethereal + perl magic to do that.

Something similar is already available in ethereal if you just want to
verify that
bulk tcp transfers are behaving properly:


The 5 second method to verify if the tcp layer is a-ok or not for optimal
throughput for bulk transfers:
==================================================

Select one packet in the direction of the tcp bulk transfer performane
analysis.
Select Tools/TCP Stream Analysis

Apply eyeball to graph:
* If after zooming in looks like a straight line from bottom left to top
right corner
everything is a-ok on the tcp layer.
* If you get a staircase where the height of each step is approximately the
same height
you have a problem with tcp window size being too small.
The width of each step should only vary a little and is the RTT for the
flow.
This effect is caused by having the tcp window smaller than what can be
transmitted end-to-end during one RTT and this small tcp window size is
capping throughput.
Increase the tcp window size to compensate for the end to end latency.
* If you get a staircase with different heights of the steps and also widely
varying lengths of the steps, with some steps being very long/wide. Then
what you see is normal (i.e. non-fast) tcp
 retransmissions which kills your performance.
Ivestigate what is causing the congestion/packet-loss and reduce it and
performance will
be enhanced.
This often means that the tcp window size is too high and that this causes
bursts that will overflow
a buffer somewhere.



----- Original Message -----
From: victor.lee
Sent: Tuesday, April 01, 2003 12:12 AM
Subject: [Ethereal-users] TCP performance measurment in csv format


Hi,

I would like to know if there is a good method to calculate the end-to-end
TCP throughput against time and converted the result into a csv file in
other for further Excel post-processing.

Cheers,

Victor Lee

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