Re: iperf different numbers on server vs. client
Well you are sending like 4 packets. The times are so small that a couple
microseconds can have a huge effect on bandwidth. There are a large number
of reasons that different streams will have different bandwidth, the
biggest being TCP and thread scheduling. Given enough time for TCP to
reach steady state the difference will shrink. Also with more time most of
the factors begin to drop out.
Kevin
On Tue, 25 Mar 2003, Jason Axley wrote:
> I'm using iperf and get vastly different bandwidth results from the server
> and client's perspective when using parallel connections from the client
> and specifying the -n and -l options to control how much data is sent from
> the client.
>
> The results are very similar, if not identical, when using the defaults.
> Why are the results so different? I would expect that both would report
> the same values. If not, what is the server reporting its numbers on?
> Which one would be a more reliable measure?
>
> The OS is Solaris 5.8; iperf version 1.6.5 (13 Jan 2003) pthreads
>
> Thanks,
>
> -Jason
>
> Server (removing extraneous information lines):
> iperf -s -p 5001
> ------------------------------------------------------------
> Server listening on TCP port 5001
> TCP window size: 64.0 KByte (default)
> ------------------------------------------------------------
> [ ID] Interval Transfer Bandwidth
> [ 6] 0.0- 0.0 sec 4.00 KBytes 59.3 Mbits/sec
> [ 7] 0.0- 0.0 sec 4.00 KBytes 437 Mbits/sec
> [ 8] 0.0- 0.0 sec 4.00 KBytes 504 Mbits/sec
> [ 9] 0.0- 0.0 sec 4.00 KBytes 141 Mbits/sec
> [ 10] 0.0- 0.0 sec 4.00 KBytes 529 Mbits/sec
> [ 11] 0.0- 0.0 sec 4.00 KBytes 475 Mbits/sec
> [ 12] 0.0- 0.0 sec 4.00 KBytes 520 Mbits/sec
> [ 13] 0.0- 0.0 sec 4.00 KBytes 282 Mbits/sec
> [ 5] 0.0- 0.0 sec 4.00 KBytes 4.81 Mbits/sec
> [ 4] 0.0- 0.0 sec 4.00 KBytes 1.45 Mbits/sec
>
>
> Client:
>
> iperf -c dh12017 -p 5001 -n 4k -l 4k -P 10
> ------------------------------------------------------------
> Client connecting to dh12017, TCP port 5001
> TCP window size: 64.0 KByte (default)
> ------------------------------------------------------------
> [ ID] Interval Transfer Bandwidth
> [ 6] 0.0- 0.0 sec 4.00 KBytes 24.5 Mbits/sec
> [ 7] 0.0- 0.0 sec 4.00 KBytes 10.9 Mbits/sec
> [ 8] 0.0- 0.0 sec 4.00 KBytes 5.98 Mbits/sec
> [ 10] 0.0- 0.0 sec 4.00 KBytes 4.20 Mbits/sec
> [ 11] 0.0- 0.0 sec 4.00 KBytes 3.78 Mbits/sec
> [ 12] 0.0- 0.0 sec 4.00 KBytes 3.47 Mbits/sec
> [ 13] 0.0- 0.0 sec 4.00 KBytes 3.16 Mbits/sec
> [ 5] 0.0- 0.0 sec 4.00 KBytes 6.03 Mbits/sec
> [ 4] 0.0- 0.0 sec 4.00 KBytes 6.89 Mbits/sec
> [ 9] 0.0- 0.0 sec 4.00 KBytes 3.45 Mbits/sec
>