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Archive for August, 2010

Modify your NIC MTU size setting in Windows Registry

August 12th, 2010 No comments

A quick and easy blog post today on how to modify your NIC MTU (Maximum Transmission Unit) size setting in the Windows Registry.

By default your MTU won’t be defined in registry. Microsoft state that (Link):

The MTU is usually determined by negotiating with the lower-level driver. However, this value may be overridden.

To change your MTU setting in Windows Server 2003 or 2008 use the following steps:

  • Open regedit as an administrator account on the server in question.
  • Navigate to HKLM\System\CurrentControlSet\services\Tcpip\Parameters\Interfaces\[Choose the interface in question] (Do this by checking the correct IP address is in the settings under this key for the adapter you are configuring)
  • Once you are in the correct key for your interface, right-click and select new DWORD value (32 bit).
  • Call it MTU
  • Give this a decimal value equal to the setting you would like your MTU to be (measured in bytes).

For more information about Maximum Transmission Unit sizes, have a look at the official Wikipedia article.

Here is a screenshot of an MTU setting I made on this server using 1400 bytes as an example. This would obviously be tuned to whatever amount you are wanting to use for your NIC and specific application settings.