Switching is generally understood to be the way in which a transmission path is mediated between sender and receiver. A basic distinction is made between line switching and memory switching. In addition, optical transport networks use various switching techniques, including wavelength routing and wavelength switching.
In the case of circuit switching, a physical connection is established between the transmitter and receiver via one or more switching units, for the duration of the transmission. Circuit switching is suitable for real-time transmissions ofall types: for voice transmissions as well as for videotransmissions.
In memory switching, the message is temporarily stored in the switching units until further transport is possible. A distinction is made in this technology between data packet switching and message switching.
In data packet switching, the information to be transmitted is converted into data packets and transmitted via the data packet network. The data packets are buffered in the nodes one after the other with channel number and switching info and forwarded. Data packet switching is particularly suitable for the transmission of data that is not time-critical, such as occurs in file transfer or e-mail applications.
Message switching, like data packet switching, is based on the principle of memory switching. In message switching, the message is transmitted as a whole together with the destination address from the subscriber to the next exchange and from there to the next exchange or to the receiving subscriber. The main difference between the two switching techniques is that in circuit switching a specific bandwidth is permanently allocated to a connection, whereas in packet switching this is requested on demand.