Circuit switching
The circuit switching (also circuit switching, Eng. Circuit switching, line switching) in telecommunications is a method of switching technology, in which a communication link temporarily a circuit-switched communication channel is assigned with constant bandwidth, the then available of this compound for exclusive use, even if no information is transferred.
The most famous network that makes connections to circuit switching, is the conventional telephone network.
The connection is established as a rule based on the input destination information from the calling terminal before the actual message exchange can start. After the end of the message exchange, a reduction of the compound. The control of the assembly and disassembly in the communications network is carried out by the exchanges. For this purpose, they exchange with the terminals and with each other control information, which is referred to as signaling or signaling. Use this control information, the tasks of the path search, traffic management and routing - switching through be performed.
Since the switches learn all the necessary information during the connection setup, the messages if a connection has on the intermediate stations must not be cached ( engl. Store and forward ) and contain no additional destination information. Circuit switching has the advantage that qualities of service in regard to the transmission rate can be maintained at all times and the signal propagation delays are constant, ie occur only delays a known and constant delay between the transmitter and receiver. However, the connection is time consuming. Communication relationships with multiple partners require a repeated structure and both participants must send and receive the same capacity.
A virtual connection (English Virtual circuit) can be based on packet-switching technology and the emulation of a circuit switching. In this case, a connection is established and transmitting the packets to the correct order.
More complex than the line switching mechanisms using packet switching in which a transmission channel is not used exclusively at the same time for a communication link but for multiple connections. A combination of circuit and packet switching used early packet networks such as Datex -P.