Thank you very much Marc,
Is there a reason why the client would not send udp data higher than ~115Mbps
till I lower the datagram size to about 900 bytes? (when I do this it goes to
about 700Mbps on a 1Gbps link). This is regardless of my buffer size on both
the client and sever machine.
On a seperate test, I also noticed that if I have the exact same setup with
identical Windows PC's connected locally to a 100Mbps switch and all my ports
were running at 100Mbps, the bandwidth the client sends does not seem to follow
any specific trend. For example, if I set the client to send in 1,25, or
50Mbps, the client does seem to send packets at that rate. However, when I
increase it to 100Mbps, it no longer scales and continues to send data at
~50Mbps. The rate it sends the data starts to increase at about '-b150m'. It
peaks at about -b185m where it sends data at about ~94Mbps. If I increase the
value of '-b' a little further, the client sharply drops its sending rate to
about ~63-64Mbps (again this is regardless of the buffer size I have on the
client and server).
Any input you can provide on the machanics of this is greatly appreciated,
Best Regards,
Yousuf,
> Date: Tue, 23 Feb 2010 13:00:53 +0000
> Subject: Re: [Iperf-users] Iperf UDP parameters
> From: marc.herb...@free.fr
> To: yous...@hotmail.com
> CC: iperf-us...@dast.nlanr.net
>
> 2010/2/22 Yousuf Ahmad <yous...@hotmail.com>:
> > How does iperf use “b, w and l” parameters?
>
> AFAIK Iperf does nothing with the socket buffer size argument ('-w')
> but pass it to your operating system.
>
>
> > Is there a way I can calculate or estimate their value in order to achieve
> > max. UDP throughput for a given link?
>
> Not without understanding the TCP/IP stack of your operating system
> (this is of course much easier with an open-source system).
>
> Regards,
>
> Marc
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