In asynchronous transfer mode (ATM), 8 bits in the cell header that identify the virtual path (VP), which is determined at the input port and is fixed for each call, and is shared among multiple calls.The path is from switch input port, through the switching matrix, to the output port, and then across a link between any two consecutive ATM entities and, therefore, has only local significance. See also ATM, ATM reference model, cell, header, link, port, switch matrix, and VP.