Line switching

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The circuit switching (including circuit switching , Engl. Circuit switching , line switching ) in telecommunications is a switching technology , in which a communication link temporarily a circuit-switched transmission channel with constant bandwidth is assigned, which then is this compound for the exclusive use available even if no information be transmitted.

Probably the best-known network that establishes connections with line switching is the classic telephone network .

As a rule, the connection is established on the basis of the destination information entered by the calling terminal before the actual exchange of messages can begin. After the exchange of messages has ended, the connection is cleared down. The control of the establishment and dismantling of the communication links is carried out by the switching centers . For this purpose, they exchange control information with the terminals or with each other, which is referred to as signaling . With the help of this control information, the tasks of route search , traffic control and switching matrix switching are carried out.

Since the switching centers receive all the necessary information while the connection is being set up, the messages do not have to be temporarily stored at the intermediate stations when the connection is established ( store and forward ) and do not have to contain any additional destination information. Line switching has the advantage that quality of service with regard to the transmission speed can be maintained at all times and the signal transit times are constant; so there are only delays of known and constant transit time between sender and receiver. However, establishing a connection is time-consuming. Communication relationships with several partners require repeated establishment and both participants must send and receive with the same capacity.

A virtual connection (Engl. Virtual circuit ) can be applied to packet switching and the emulation based circuit switching. A connection is established and the packets are transmitted in the correct order.

More complex mechanisms than circuit switching use packet switching , in which a transmission channel is not used exclusively for a communication connection, but for several connections at the same time. A combination of circuit and packet switching used early packet networks such as B. Datex-P .


  • Rolf Herheuser: Planning of switching networks . Vdf Hochschulverlag, Zurich 2008, ISBN 978-3-8252-8394-0 .
  • James F. Kurose, Keith W. Ross: Computer Networks. Pearson Education, Munich 2008, ISBN 978-3-8273-7330-4 .
  • Martin Bossert, Markus Breitbach: Digital networks. BG Teubner Verlag, Stuttgart 1999, ISBN 3-519-06191-0 .
  • Martin Meyer: communication technology. Second edition, Friedrich Vieweg & Sohn Verlag, Braunschweig 2002, ISBN 978-3-322-93951-7 .
  • Martin Werner: Networks, protocols, interfaces and communication. 1st edition, Friedrich Vieweg & Sohn Verlag, Braunschweig 2005, ISBN 3-528-03998-1 .

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