Re: Iperf: UDP question
Hi,
have you done the same tests on UNIX or Linux? It seems like there
might be a problem with clock resolution on windows in which case it
would mean that iperf is having problems calculating the speed.....but
I wonder why the same problem won't occur with TCP...
If you try out the tests with Linux, please let me know the results.
Thanks
Najaf
On 9/16/05, Rosanna <rosannajaimes --at-- cantv.net> wrote:
> Hello
>
> I also got similar results when I run Iperf version 1.7.0 in 2 PC´s with 100
> Mbps cards, connected through a switch. Initially both nodes got Windows XP,
> then I tested in one node with Windows Server 2003 and the second node with
> Windows XP, to see if I got any difference, but results were the same.
>
> For TCP, I got nearly 94 Mbps but for UDP I got approximately 60 Mbps. I
> agree that UDP should be faster but I haven´t figured out yet why this is
> happening.
>
> The command I used to get that UDP throughput was:
>
> iperf -c serveraddress -u -b 100G <--- Observe that I used a bit
> rate higher than system bandwidth
>
> iperf -s -u
>
> The only way I got a better UDP throughput (around 91 Mbps) was changing the
> socket buffer size (-w) and the datagram length (-l). I used the following
> commands to do so:
>
> iperf -c serveraddress -u -b 100G -w 128k -l 32k
>
> iperf -s -u -w 128k -l 32k
>
> I will also appreciate if someone knows what is happening.
>
> Thanks, Rosanna
>
> ----- Original Message -----
> From: "Najaf A. Shah" <najafali --at-- gmail.com>
> To: <iperf-users --at-- dast.nlanr.net>
> Sent: Monday, September 12, 2005 9:16 PM
> Subject: Iperf: UDP question
>
> > Hi,
> > I've been using IPerf for doing some tests on our
> > network. For TCP tests, I'm able to get around 94
> > mbps between two systems. However, the speed drops to
> > around 30 mpbs over UDP. Shouldn't UDP be faster?
> >
> > I've googled this but haven't come up with a good
> > answer. Is it IPerf not doing the measurements
> > correctly or is it something with Windows XP?
> >
> > The commands I'm using are:
> >
> > iperf -c -u myserversIP -b 100M -p 5002
> >
> > iperf -s -u
> >
> > If someone can give me some clues on this I'd really
> > appreciate it.
> >
> > Also, is there a webpage that lists the max, min, and
> > default parameter values for things such as packet
> > size, etc for Windows and Linux?
> >
> > Thanks
> >
> > Najaf
> >
> >