If we want to change the MTU of interface eth1 to 9000 we use this command:

# ifconfig eth1 mtu 9000 up

This change is not permanent and doesn’t survive a reboot. However it is useful to for test before making it permanent.

In order to make it permanent we have to add the following directive to the interface script in /etc/sysconfig/network-scripts

In order to ping and determine the packet size and set it not to fragment we can use the following command:

# ping 192.168.200.71 -M do -s 1477

In which -s is the packet size and “-M do” is in order for the packet not to be fragmented.

In XenServer this has to be done through XenCenter. Select the Xen server and then under Networking tab select the name of the network that you want to change the MTU.

Properties –> Network Settings –> MTU

After changing the MTU check it by logging into XenServer using SSH. If the value of MTU is larger than the max that is supported by Xen server, Xen Center doesn’t return any error and keeps it in the MTU field but it doesn’t take effect in the server.

In Nic properties windows click on “Configure”

Then select “Jumbo Packet” in the property list and choose the proper value for MTU (usually 9000 or 9014)

Sometimes the above process doesn’t take effect without returning any error message. So it is necessary to verify the MTU using CLI

C:\> netsh interface ipv4 show interfaces  (or netsh int ip sh int )

in which l is the packet size. “-f” is in order for the packet not to be fragmented.

In windows only MTU of team members can be changed and the team interface itself doesn’t have this option.

In Linux, MTU of member interfaces and bond interface can be configured.