The Maximum Transmission Unit (MTU) is the largest possible frame size of a communications Protocol Data Unit (PDU) on an OSI Model Layer 2 data network.

How is MTU determined?

The maximum transfer unit (MTU) specifies the maximum transmission size of an interface. A different MTU value may be specified for each interface that TCP/IP uses. The MTU is usually determined by negotiating with the lower-level driver. However, this value may be overridden.

What is the expansion of MTU?

The maximum transmission unit (MTU) is the largest size frame or packet -- in bytes or octets (eight-bit bytes) -- that can be transmitted across a data link. It is most used in reference to packet size on an Ethernet network using the Internet Protocol (IP).