Multiplexing and switching: preliminary concepts
ATM networks

This brief historical overview has introduced a number of fundamental concepts which we need to return to in order to establish the vocabulary of high-speed networks and ATM. The place of ATM, as a multiplexing and switching principle, needs to be clarified among digital multiplexing and switching techniques if we are to understand both its objectives and its nature. To say that ATM is a time-division multiplexing and space-switching technique, that it is a packet-mode, asynchronous technique (strictly speaking, it should have been called anisochronous) as opposed to circuit-mode, synchronous (isochronous), position-multiplexing techniques, requires that these notions at the basis of digital telecommunication networks be clearly defined.

For the sake of terminological clarity, we'll use the term "switching" here in the restrictive sense of routing information through...