MTU refers to Maximum Transmission Unit. This pertains to the maximum datagram or packet size that a network allows to be sent from one station to another. MTU is a parameter used by computer networks to control the flow of data and prevent excessive data transfer.

Normally, network technologies appropriate a certain MTU size. This parameter, however, can be changed by the network administrator. Stated below are a few examples of network technologies and their corresponding default MTU sizes. Note that the MTU size of each network technology is measured in bytes.

  • PPP or Point-to-Point Protocol has a default MTU of 296.
  • Ethernet has a default MTU of 1500.
  • 4Mb Token Ring has a default MTU of 4464.
  • Hyperchannel has a default MTU of 65,535.

In the event of a specific datagram being larger than the MTU of the network, the datagram will be fragmented into several smaller ones. Fragmentation is a process wherein data packets are divided in order for them to be permitted to transfer to another network location. There are cases where the MTU is smaller than most or all of the datagrams that need to be sent over the network. In this situation, all the datagrams have to be fragmented.

MTU can also increase bandwidth efficiency. This is done by increasing the MTU size in a network. However, increasing the size of the MTU may result to multiple sending of data due to errors that may take place.