The Internet Protocol (IP) was designed to work over an internetwork comprised of different network technologies, such as Ethernet and Frame Relay. Each network technology has a different maximum transmission unit (MTU), the maximum size of a frame that can be sent. The IP MTU is the maximum size IP packet that can be sent. A good example is Ethernet, which has an MTU of 1526 bytes. By subtracting the size of the Ethernet header and trailer (a total of 26 bytes), the IP MTU for Ethernet is 1500 bytes.

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