Ethereal-users: Re: RE: [Ethereal-users] Can you help me diagnose a performanceproblem?

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From: "Ronnie Sahlberg" <ronnie_sahlberg@xxxxxxxxxxxxxx>
Date: Fri, 30 Jul 2004 22:15:46 +1000
>From: bleonhardt
>Subject: RE: RE: [Ethereal-users] Can you help me diagnose a
performanceproblem?
>
>tcp uses windowing, so not every packet should be acknowledged - of
>course, a ACK of every packet / frame will slow down the connection as
>there's more traffic on the network than usual ..
rfc2582->rfc1122->rfc813 tells it all

a tcp should ACK (pick first that matches)
* evey segment with PSH bit set
* immediately repeat prevoius ack for segments outside the window (duplicate
ack, keepalives and zerowindow probes)
* every second full size segment upon receival
* other segments within a reasonable time but may collapse acking of
multiple acks into a single ack

>.. maybe a resize of the window-size could help .. try DrTCP ( just google
>for it ) to change the settings .. then restart your network ( 2k/xp ) or
>restart the pc/notebook.

use ping to measure end-to-end latency in seconds.  call it RTT. (unit is
seconds)
pick out of the air what throughput you want to sustain in Bytes/second.
call this TP  and unit is Bytes/second

RequiredWindowSize is then ::= TP * RTT

set tcp window size to twice this value   (to have some safety margin)