Speed Testing and Throughput testing

Michael Helmeste mhelmest at uvic.ca
Wed Nov 4 22:49:42 UTC 2009

We had a problem where our (mostly research network connected, international) users were getting generally low HTTP transfer speeds, even though the path was often gigabit. The classic high bandwidth/high latency problem.

Initially I tried using iperf/ndt and friends but found that iperf required too much user knowledge and interaction, and NDT was sometimes inaccurate at diagnosing problems -- it seemed to be overly fond of saying there was a duplex mismatch or congestion. Iperf in TCP mode either requires manually seeking the number of streams to try and find optimum throughput, or doing window size tweaks.

I also found that packet captures were useful for discovering problems in the path; you can load it up in wireshark or tcptrace and get a sequence no. vs time graph, look for packetloss, or other good things like that.

Anyways I didn't find much out there in terms of automating this type of thing (simple throughput tests with packet capture) so I just ended up making my own. It does a dump of 10 sec. of test traffic, uses a somewhat dumb algorithm to seek up the number of TCP streams, and gets an AS path from a BGP route server and displays it to the user. The caveat is that it only tests your download speed, not upload, since that was primarily what I was interested in.

You can give it a try at: http://caranthir.dao.nrc.ca/netperf-www/ (login nanog/nanog). User guide here: http://www.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/netperf/testdetail.shtml

I might end up packaging and releasing the code if there is interest.

On Mon, 2 Nov 2009 15:56:56 -0600
Mark Urbach <mark.urbach at pnpt.com> wrote:

> Anyone have a good solution to get "accurate" speed results when testing at 10/100/1000 Ethernet speeds?
> Do you have a server/software that customer can test too?
> Thanks,
> Mark Urbach
> PinPoint Communications, Inc.
> 100 N. 12th St  Suite 500
> Lincoln, NE 68508
> 402-438-6211  ext 1923  Office
> 402-660-7982  Cell
> mark.urbach at pnpt.com
> [cid:image003.jpg at 01CA5BD5.1A5CEE20]

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