Re: question about window size(receiver buffer) of iperf
On Mon, 28 Jul 2003, Mitch Kutzko wrote:
> >From: "Yung Yi" <yi --at-- ece.utexas.edu>
> >To: <dast --at-- nlanr.net>
> >Subject: question about window size(receiver buffer) of iperf
> >Date: Mon, 28 Jul 2003 02:39:16 -0500
> >
> >Dear dast,
> >
> >I have a question about window size(receiver buffer) change of iperf 1.7.1.
> >
> >When I change the window size of iperf(server mode) using -w option,
> >there are some warning messages like this.
> >
> >[root --at-- fluidsim iperf-1.7.0]# ./iperf -s -w 1024K
> >Receiver buffer is set to 1048576
> >------------------------------------------------------------
> >Server listening on TCP port 5001
> >TCP window size: 128 KByte (WARNING: requested 1.00 MByte)
> >------------------------------------------------------------
> >
> >The above message means that it's really changed into 1024K but it's too
> >large(warning) or it's not changed and the program uses 128K window size.
> >
> >The reason why I ask is that the sender in my network does not increase it's
> >sending speed due to the limitation of receiver window size.
> >
> >Best Regards,
> >Yung Yi.
> >
>
Hi there.
The FAQ for Iperf is located at:
http://dast.nlanr.net/Projects/Iperf/iperf_faq.html
It turns out that Question 19 addresses this very issue. I've copied and
pasted it for you:
--
19. Why am I unable to set a specific Window size?
Often, the operating system will not give you the window size you request.
If this happens, Iperf will show the requested amount and the actual
allocated amount.
For more information on specific operating systems and their networking
characteristics, you might try looking at some of the pages mentioned
under the Related Tools section of the main Iperf page.
--
Hopefully, the FAQ is awesome and will answer all your questions before
you ever have to ask them. If not, the Iperf-Users list will be here
(and yes, the FAQ will even tell you how to join if you haven't already).
-Damon