I was trying to move 13G of music between my Powerbook and Windows machines on my gig network at home. It would seem that SOHO switches aren’t really capable of operating at the advertised gigabit rates, and additionally, Windows XPPro-SP2 is nowhere near optimally tuned straight out of the box. At best, I was only getting close to 120Mbits/sec.
After performing some tuning based on the walkthrough found here: http://www.psc.edu/networking/projects/tcptune/OStune/winxp/winxp_stepbystep.html, I was able to get the Win -> Mac communications up to 260 Mbit/sec. Just for comparison, unoptimized Mac<->Linux rates were 260Mbit/sec using OS X 10.4 and FC 6. I suspect that the limitations of my switch will cap my throughput at that rate.
Naturally, after having done all of the edits instructed in the tutorial, I discovered that dslreports.com offers a utility called DrTCP that drastically simplifies making windows TCP tuning changes. At a minimum, you will need to restart the network interface that you’ve tuned, if you don’t simply reboot the machine altogether.
For aid in testing during the tuning I used the following utilities:
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Windows – http://www.pcausa.com/Utilities/pcattcp.htm
- Â A copy of the windows binaries are at http://www.genvmunix.com/ttcpzip.exe
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Mac & Linux – http://www.genvmunix.com/ttcp.c
- The source compiled without any changes with a few warnings doing just a cc -o ttcp ttcp.c on both unix variants.
- If I can find a netperf client as well I will rerun my testing using that utility.
When time permits, my final round of testing will involve directly connecting the machines together and see what kind of rates I can get by eliminating the switch altogether. For now I have settled with the 260 MBits/sec.
>>>Karl
