Cell - ATM Cell (ATM)
A cell is the basic data unit of the ATM (Asynchronous Transfer Mode) protocol. Cells contain identifiers known as VCI (Virtual Channel Identifier) and VPI (Virtual Path Identifier) to associate the cells with a logical data stream. Each cell consists of a 5 byte header and 48 bytes of payload. The cells are small in order to facilitate low processing delay and so high speed transmission.