MTU Ping Test

A series of ping tests using the command, ping www.expedient.net -f -l xxxx, where xxxx is the packet size, can be used to determine the optimal MTU for your connection.

• Go to Start and select Run.
• Type in cmd (Windows 2000/XP) or command (Windows 98/ME) into the Open: field. Hit the enter key or click OK. The DOS prompt should open.
• At the DOS prompt, type in ping www.expedient.net -f -l 1492 and hit the Enter key.
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• Note the results above indicate that the packet needs to be fragmented. Lower the size the packet in increments of +/-10 (e.g. 1472, 1462, 1440, 1400) until you have a packet size that does not fragment.
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• Begin increasing the packet size from this number in small increments until you find the largest size that does not fragment. Add 28 to that number (IP/ICMP headers) to get the optimal MTU setting. For example, if the largest packet size from ping tests is 1462, add 28 to 1462 to get a total of 1490 which is the optimal MTU setting.
• Change the MTU using DrTCP or editing the registry. See MTU Settings for further information.

http://strongvpn.com/mtu_ping_test.html

Misc Tools

• MTU Ping Test
• Adjusting MTU
• Speed Test