Computer Hardware Terms, Glossary and Dictionary

Maximum Transmission Unit (MTU) is the largest physical packet size in bytes that can be passed by a layer of a communications protocol. A MTU parameter is usually associated with a communications interface (NIC, serial port, etc.). Each type of networks may have different size of MTU. The MTU for Ethernet is 1500 bytes. Higher-level network protocols like TCP/IP can be configured with a maximum packet size, but this setting is distinct from the physical MTU. Any messages larger than the MTU are divided into smaller packets before being sent. The MTU of a network has important implications on the performance of computer communications because that too large an MTU size may mean retransmissions if the packet encounters a router that can't handle that large a packet, and too small an MTU size means relatively more header overhead and more acknowledgements that have to be sent and handled.

Related Terms

MTU: Maximum Transmission Unit