David K. Hunter: Switching Systems Switching Systems

Switching systems connect and disconnect users in a communications network by activating and deactivating switching devices. At first sight, this may seem trivial, but there is, in fact, a vast literature on the subject, much of which is highly technical. This article provides a flavour of this subject and identifies some of its principal features. It starts by looking at some key results from the mathematical theory of switching, providing idealized models of real switching systems and yielding useful insights into them. After that, time switching and packet switching are discussed and some switching systems currently in the research stage using a new technology – optical switching – are described.