The RWIN calculation requires a latency value for a large packet, pinged some distance and averaged.

To find this value, open a command prompt and type: ping -t www.xxx.xxx -l 1472
(where www.xxx.xxx is any URL you like as long as it's fairly distant from you.)

Note that the -l is a lower case L, not an I. Also note that if you use PPPoE, use 1464 or lower, not 1472. In other words, use a number that is 28 less than your reported MTU.

If you are on the east coast of the US, for instance, you'd want to pick a western URL. Colleges seem to work well since their websites are generally located somewhere on campus.

If the pings time out, you've chosen a URL that is blocking ping. Press "Ctrl" and "C" together and the request will stop. Choose a different URL and try again. Once you find a site that responds, let it run for two or three minutes and then press "Ctrl" and "C" together.

A summary will be displayed showing an average result time in milliseconds. Multiply this value by 1.5 and use the result in the RWIN calculation formula.

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by garp123 edited by JMGullett
last modified: 2007-02-27 09:54:48