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I have two windows servers on the same network, communicating to each other. What would be the best way to come up with the MTU setting?

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2 Answers 2

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An easy way to determine your best MTU value, which should make your tinkering a lot less complicated: Start by opening a dos prompt, then enter this following command:

ping -f -l [trial MTU number] [other server IP]

Start with 1400 and go up or down depending on the message (if it tells you that the packets are being fragmented, you need to go down - you want the highest setting that doesn't cause packet fragmentation). To derive your MTU from the ping data, add 28 to the highest number that worked (packet size+28).

For example: Ping -f -l 548 10.0.0.3 If this does not cause packet fragmentation, use 576 for MTU because 548+28=576

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In my experience, the default MTU in Windows doesn't need adjusting. Why do you think you need to modifiy the MTU? Does your network infrastucture (switches) support MTU sizes other than the standard Ethernet MTU of 1500? (I'm assuming we're talking Ethernet here).

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