Configure TCPIP Max Transfer Unit (MTU) size

5 July 2007 by Snakefoot | Comment » | Trackback Off

The default Max Transfer Unit (MTU) size for ethernet is 1500 bytes, if using a network with a different MTU size, then one should make sure to configure MTU in Windows to avoid packet fragmentation or connection loss.

Open an Elevated Command Prompt and run this command to view current MTU size of the available IPv4 sub-interfaces (Can also be done with IPv6):

netsh interface ipv4 show interfaces

To change the MTU size of sub-interface no. 1 (See "Idx" from above command):

netsh interface ipv4 set subinterface 1 mtu=1500 store=persistent

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Updated: 26 July 2012

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Comment by Phantom - 5 July 2008 @ 1:03 Reply

The show interfaces line reveals that the loopback is set to a much higher number, should that be changed to 1500 as well?

Comment by Coscu - 8 July 2008 @ 4:31 Reply

i have make a change with a friend in the MTU but now we want to delete it and we dont know the command =/ can someone help ?

Comment by kontol - 8 July 2008 @ 20:28 Reply

If you have more than one NICs and you want to see which subinterface is, you need to run:

netsh interface ipv4 show interfaces

The result will be like this:
Idx Met MTU State Name
— — —– ———– ——————-
1 50 4294967295 connected Loopback Pseudo-Interface 1
17 25 1500 connected Wireless Network Connection 1
19 25 1500 connected Wireless Network Connection 2

Hence, if you like to change MTU of “Wireless Netwrok Connection 1″, you should run command:

netsh interface ipv4 set subinterface “17″ mtu=1384 store=persistent

and so on for the other interfaces.

Comment by Snakefoot - 8 July 2008 @ 20:59 Reply

Phantom
The show interfaces line reveals that the loopback is set to a much higher number, should that be changed to 1500 as well?

The loopback adapter can only communicate with the local machine hence the name. No need to change the MTU.

Comment by Lennon Zimmerman - 13 June 2009 @ 21:18 Reply

When looking in the ipv6 i find 6 other NICs but they are not given a index number. How do i change the MTU for these?

Comment by MOMO - 6 February 2010 @ 11:43 Reply

Dear All,
Could you help me for the below issue.
I’ve a VoIP device (SBC) that’s connected to a L2 network then to a router.
The problem is that the Server interface is divided into several logical subinterfaces(the same for the router) & each interface has its own VLAN tag.
I dont have any administration right for both the router & the L2 network while I need to connect my vista PC instead of the SBC to troubleshoot a problem.
This means that I’ve to make my PC undersatand VLAN ID as the router is going to send the packets tagged to me.
Do you have any idea of how to make my PC aware of tagged packets?

Comment by Rafael - 14 June 2010 @ 2:45 Reply

In my case, when I type the netsh interface ipv4 set subinterface “11″ mtu=1384 store=persistent - 11 is in my case - I get an error: the following command was not found. What can I do ??

Regards.

Comment by Michael - 23 November 2010 @ 10:53 Reply

The correct command would be:
netsh interface ipv4 set subinterface interface=11 mtu=1384 store=persistent

Then it should work fine

Comment by John - 21 September 2012 @ 21:16 Reply

Michael’s command works correctly for me. Many thanks.

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