Adapter MTU setting

All devices on the same physical network, or logical network if using VLAN tagging, must have the same Media Transmission Unit (MTU) size. This is the maximum size of a frame (or packet) that can be sent on the wire.

The various network adapters support different MTU sizes, so make sure that you use the same MTU size for all the devices on the network. For example, you can not have a Gigabit Ethernet adapter using jumbo frame mode with a MTU size of 9000 bytes, while other adapters on the network use the default MTU size of 1500 bytes. 10/100 Ethernet adapters do not support jumbo frame mode, so they are not compatible with this Gigabit Ethernet option. You also have to configure Ethernet switches to use jumbo frames, if jumbo frames are supported on your Ethernet switch.

It is important to select the MTU size of the adapter early in the network setup so you can properly configure all the devices and switches. Also, many AIX® tuning options are dependent upon the selected MTU size.