Are We Moving Back to Fixed Cells?
One of the core issues of the argument between Asynchronous Transfer Mode (ATM) and the Internet Protocol (IP) was the fixed cell size. While IP network rely on variable length packets, ATM, in order to facilitate faster switching speeds, and in order to interoperate better with the many different Time Division Multiplexing (TDM) physical layers, specified fixed length cells. IPv4, in particular not only provides for a variable length packet, but fragmentation in flight. The figure below illustrates.