A maximum transmission unit (MTU) is the largestsize packet or frame, specified in octets (eight-bit bytes), thatcan be sent in a packet or frame-based network such as theInternet. The Internet´s Transmission Control Protocol uses the MTU to determine the maximum size of each packet in any transmission. Too large an MTU size may mean re-transmission if the packet encounters a router that can´t handle that large a packet. Too small an MTU size means relatively more header overhead and more acknowledgements that have to be sent and handled. Most computer operating systems provide a default MTU value that is suitable for most users. In general, Internet users should follow the advice of their Internet service provider (ISP) about whether to change the default value and what to change it to.
