Sets the IP maximum transmission unit (MTU) globally or on an interface.
The default IP MTU size is 1500 bytes.
Global configuration mode
Interface configuration mode
Port-channel configuration mode
The no form of the command reverts the MTU size to the default value.
Using the no form of this command in global configuration mode resets the default value on all interfaces except the interfaces that you manually configured with MTU values.
When you change the IP MTU size globally, the change is applied to all Ethernet and VE interfaces on the device. However, it does not change a configured interface MTU value. The configured interface value takes precedence over the configured global MTU value.
The show running-config command displays the the MTU size when it is not the default value. If you change the global MTU size and do not change the interface MTU size, the show running-config command does not display the global MTU value at the interface level.
If the interface is part of a VE, change the IPv4 MTU only at the VE interface and not at the physical port. All member ports of a VE inherit the VE-interface IPv4 MTU value.
The following example sets the IP MTU to 2000 bytes on the specified Ethernet interface.
device# configure terminal device(config)# interface ethernet 2/9 device(conf-if-eth-2/9)# ip mtu 2000
The following example changes the IP MTU for a VE.
device# configure terminal device(config)# interface ve 103 device(config-vif-103)# ip mtu 2000
The following example changes the IP MTU globally.
device(config)# ip mtu 2000