How do I find the proper MTU size on my router?

To find the proper MTU Size, you'll have to do a special ping ofthe destination you're trying to go to. A destination could beanother computer, or a URL.

Step 1 Click on Start and thenclick Run.

Step 2 Windows 95, 98, and ME users type incommand (Windows NT, 2000, and XP users type incmd) and press Enter (or clickOK).

Step 3 Once the window opens, you'll need to do aspecial ping. Use the following syntax:

ping [url] [-f] [-l] [MTU value]

Example: ping yahoo.com -f -l 1472


You should start at 1472 and work your way down by 10 each time.Once you get a reply, go up by 2 until you get a fragmented packet.Take that value and add 28 to the value to account for the variousTCP/IP headers. For example, lets say that 1452 was the propervalue, the actual MTU size would be 1480, which is the optimum forthe network we're working with (1452 28=1480).

Once you find your MTU, you can now configure your router with theproper MTU size.

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