From: Donnie Hale (donnie@haleonline.net)
Date: 07/22/03
From: "Donnie Hale" <donnie@haleonline.net> Subject: RE: tcptrace TCP window utilization Date: Tue, 22 Jul 2003 18:44:51 -0400 Message-ID: <INECKHKOHJGEDEFOMDPMAEFGCHAA.donnie@haleonline.net>
I'm definitely not looking for advertised window info, at least with respect
to the question I asked. I'm not sure if the "owin" item is what I'm looking
for or not. Some other utilities I've seen dub the info I'm looking for "max
unacknowledged data" or "max in-flight data"; i.e. the max bytes that an
endpoint actually streamed onto a connection before stopping to wait for an
ack. If that's what "owin" means, then that's what I'm looking for.
Thanks,
Donnie
-----Original Message-----
From: sdo@picard.cs.ohiou.edu [mailto:sdo@picard.cs.ohiou.edu]On Behalf
Of Shawn Ostermann
Sent: Tuesday, July 22, 2003 6:09 PM
To: Donnie Hale
Cc: Tcptrace Maintainers
Subject: Re: tcptrace TCP window utilization
Donnie Hale <donnie@haleonline.net> wrote:
> I've just started using tcptrace, and I clearly have a ways to go to
> understand all the implications of its detailed output.
>
> I'm wondering if tcptrace can output the maximum (and perhaps min/avg as
> well) window size *reached* (as opposed to advertised) for each direction
in
> a connection. I'm looking to get more concrete info on if an app protocol
is
> taking advantage of the window size that the other endpoint advertises.
This
> information may be in the "-l" output and I don't know which identifier
> indicates this info. If you could point me in the right direction, I'd
> appreciate it.
Looking at the advertised window might get you into trouble, because
the sender is allowed to shrink it in certain circumstances (to save
memory, for example). What you're really looking for, I suspect, is the
maximum 'congestion window'. Tcptrace estimates that value with the
'owin', or "outstanding window". In recent versions of tcptrace, you
can get it to print some simple stats on that value with the '-W' flag.
--sdo
----------------------------------------------------------------------------
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Dr. Shawn Ostermann - EECS Department Chair - Ohio University
330 Stocker Center, Ohio University, Athens, Ohio 45701-2979
ostermann@eecs.ohiou.edu -- FAX: (740)593-0007 -- Voice: (740)593-1566
http://www.eecs.ohiou.edu/faculty/ostermann.html
http://www.eecs.ohiou.edu
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