Switching technology

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The switching technology is a branch of communication engineering that deals with the procedures and technical equipment for the production of only temporarily existing communication links between changing terminals via a communication network is concerned. The terminals (subscribers, terminals , telephones , modems ) are connected to the communications network and identified by a telephone number or address. When setting up and clearing call connections and operating the terminals, the terminals exchange signaling information with the network, for example the dialed number, indications for the occupancy of the lines and, with older analog subscriber signaling, audible tones and the call signal . The principles of switching technology are also used in conventional telephone systems.

In contrast to switching technology, multiplex technology does not have signaling technology for setting up and clearing communication links. With multiplex technology, the connections are also only switched temporarily. In multiplex technology, however, the connection path is switched via a central control that can be implemented in a network management system . Because of the similarity of the technologies, multiplex technology is often viewed as a branch of switching technology.

Tasks of switching technology

The tasks of switching technology are connection establishment, message transmission and disconnection.

Connection establishment
While the connection is being established, a (also virtual) connection is established from the message source to the message sink, which can also be several. Various signaling algorithms are run through and when communication is ready, a communication channel is opened from the source to the sink. The terms source and sink denote the logical level of action and reaction, not the direction of data transmission in the communication channel.
The message transmission is the transparent exchange of information between the participants. Charge information can be registered during transmission.
When the connection is disconnected , the message channel is closed and all technical facilities involved are released.
Configuration interface for subscriber and line functions, overload protection, traffic monitoring.

Basic structure of the switching facility

The switching equipment (VE) consists of the periphery, that is, connection modules for terminal equipment and connecting lines to other VE, the switching network and the controller (e.g. coordination processor). The control can take place centrally or decentrally.

The digital switching technology

The digital switching technology is part of the public digital communication network. Different systems are used in Germany depending on the network operator . Deutsche Telekom uses the S12 and EWSD systems in its network .

Main parts

The main parts of digital switching technology are the connection part, call connection, codec , switching arrangement of the PCM switching, switching center, switching matrix and control.

  • Connector with BORSCHT functions
  • Coupling arrangement of the PCM exchange. The switching arrangement establishes connections between the channels of the feeder groups and channels of the customer groups. To increase the performance of the switching arrangement, it can contain several switching stages. Coupling arrangements can consist of space multiple, time multiple or a combination of both. See also digital switching center , switching field , EWSD .

Different switching techniques


  • Karl Steinbuch: communication technology. Springer Verlag, Berlin / Heidelberg 1977.
  • Cornelius Neutsch: From the wing telegraph to the Internet. Franz Steiner Verlag, Stuttgart 1998, ISBN 3-515-07414-7 .
  • Wolf-Dieter Haaß: Handbook of the communication networks. Springer Verlag, Berlin / Heidelberg 1997, ISBN 978-3-642-63825-1 .

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