The Turing switch is a logical construction similar to the Turing machine

Turing machine

A Turing machine is a theoretical device that manipulates symbols on a strip of tape according to a table of rules. Despite its simplicity, a Turing machine can be adapted to simulate the logic of any computer algorithm, and is particularly useful in explaining the functions of a CPU inside a...

. The Turing switch models the operation of a basic network switch

Network switch

A network switch or switching hub is a computer networking device that connects network segments.The term commonly refers to a multi-port network bridge that processes and routes data at the data link layer of the OSI model...

 in a network of switches, much the same as a Turing machine models the operation of a basic computational entity. Both are named in honor of the English logician Alan Turing

Alan Turing

Alan Mathison Turing, OBE, FRS , was an English mathematician, logician, cryptanalyst, and computer scientist. He was highly influential in the development of computer science, providing a formalisation of the concepts of "algorithm" and "computation" with the Turing machine, which played a...

. Some introductory research on the Turing switch was started at the University of Cambridge

University of Cambridge

The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...

 by Jon Crowcroft.

In essence, Crowcroft suggests that instead of using general purpose computers to do packet switching, the required operations should be reduced to application specific logic and then that application specific logic should be implemented using optical components. The work is not actually based on Turing's research.

A Turing switch consists of a switching fabric

Switched fabric

Switched fabric, switching fabric, or just fabric, is a network topology where network nodes connect with each other via one or more network switches . The term is popular in telecommunication, Fibre Channel storage area networks and other high-speed networks, including InfiniBand...

, one or more ingress interfaces (also referred to as sources), one or more egress interfaces (sinks), and a decision procedure to determine an egress interface given an ingress interface. Interfaces are sometimes referred to as ports. A packet (cell or switched unit) arrives at an ingress interface, the appropriate egress interface is determined by the decision procedure, and the packet is then transported across the switching fabric to the egress interface. A packet is a symbol or sequence of 1's and 0's. An ingress interface is connected to an ingress line, an egress interface to an egress line. The ingress line is said to feed the ingress interface; the egress interface feeds the egress line.