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Was testing out some wireless equipment today using iperf on (at first) two Windows XP workstations. Throughput testing was fairly consistent at around 18Mbps.

Moved equipment around (outside), tested again this time with a Windows 7 laptop and one of the XP machines again and throughput dropped to ~4Mbps. Thinking that I somehow had incorrect gain settings, poor LoS, etc., I changed configuration several times but to no avail.

Brought the gear back indoors and setup the antennas exactly as they had been with my original XP-to-XP iperf tests, reverted the configuration to as it was, but still using the laptop as the iperf server (-s) and again, ~4Mbps throughput.

As a sanity check, I plugged the patch cable into the second XP workstation as I had originally tested it and voila: 18Mbps avg. throughput.

My question is: is this a known issue with iperf 2.0.5 on Windows 7 (compiled using cygwin) or is there something on Windows 7 as far as network settings that I should be looking at? Windows 7 laptop is a higher-end Dell laptop; only a few months old. Not sure of the NIC manufacturer at this point so could be Intel or Broadcom I imagine (the latter may be the culprit?).

gravyface
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Gravyface, I have had similar experiences as you have described... all under Windows XP... my solution to this issue was to burn a couple of Knoppix discs. My results instantly made sense, which leads me to believe it was an issue due to "something from Redmond"... but I couldn't say what it was.

Mike Pennington
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  • I normally use a couple of Linux netbooks for this; didn't have them with me, but yeah, a bootable distro would be good to leave in the car just in case. – gravyface Apr 27 '11 at 23:19