Here are the procedures for adjusting RWIN for on Microsoft Windows systems:

0) Baseline your current throughput

telus.net Speedtest

Select 1meg test and click test button. Repeat test 4-5 times and compute average throughput.

1) Verify current RWIN setting

DSL Reports Tweak Test

(click on "Start" button to run test)

Results will look like:

* Results
* Your public IP address is 209.214.36.138
* Your MTU is set ok
* Wide variation in ping, 54 to 311
* Quick packet-loss tested ok
* Your RWIN is set ok at 16384
* Conclusion.. HEALTHY SETUP!
* End

Note your RWIN setting.

2) Compare to RWIN requirements

Compare your RWIN to typical b*d values.

If you want a more accurate setting, you may want to ping a few hosts that you frequently access to determine actual delays. If your measurements differ significantly from those in the typical table, you may want to recalculate your RWIN requirements.

If your RWIN is already set greater than the requirement, then there no need to change anything. If it is significantly greater, then you might actually want to reduce it. If your RWIN is set too low, then adjust as follows:

3) Adjusting RWIN

Warning: The following procedures will modify your Windows Registry. Proceed at your own risk.

Right-click on the appropriate file above and save as to your Desktop. These files automatically set your RWIN value to 32KB which should be acceptable for most circumstances. Double-click on the file on your desktop.

If you need a different value, then manually edit the downloaded file and adjust the value to your needs before executing it.

Reboot your system.

4) Verify RWIN settings

Repeat step 1 to ensure that RWIN has been adjusted as expected.

5) Baseline Throughput

Repeat step 0 to determine impact of RWIN change.

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