How does circuit switching work

Information flows in two directions. Information sent from the calling end is shown in pink and information returned from the remote end is shown in blue. After a user requests a circuit, the desired destination address must be communicated to the local switching node B.

In a telephony network, this is achieved by dialing the number. Node B receives the connection request and identifies a path to the destination D via an intermediate node C. This is followed by a circuit connection phase handled by the switching nodes and initiated by allocating a free circuit to C link BC , followed by transmission of a call request signal from node B to node C.

The sender and receiver transmits communication signals to request and acknowledge establishment of circuits. Data Transfer : Once the circuit has been established, data and voice are transferred from the source to the destination. The dedicated connection remains as long as the end parties communicate. Circuit Disconnection : When data transfer is complete, the connection is relinquished. The disconnection is initiated by any one of the user.

Disconnection involves removal of all intermediate links from the sender to the receiver. This method of switching establishes a dedicated communication path between the sender and receiver.

Here the link is established in physical form between two stations present in the network. The link will be established, maintained and terminated for each communication session. The most common example of circuit switching is the Analog telephone network. This method of switching provides a constant bit delay and fixed data rate channel between the sender and receiver.

The full channel capacity is dedicated for the duration of a connection. When data is to be transferred from sender to receiver, firstly the sender sends a request to the switching station for the establishment of a connection.

The receiver replies with an acknowledgment. After receiving the acknowledgment signal the sender starts the data transmission. This switching is commonly used for voice circuits. The public switched telephone network, Datakit, B channel of ISDN, Optical mesh network, etc are some of the examples of circuit-switched networks. In this type of switching, there is a set of switches connected with physical links. See additional Computerworld QuickStudies.

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