Circuit switching is a connection-oriented network switching technique. Here, a dedicated route is established between the source and the destination and the entire message is transferred through it.
Circuit Establishment : In this phase, a dedicated circuit is established from the source to the destination through a number of intermediate switching centres. 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.
The following diagram represents circuit established between two telephones connected by circuit switched connection. The blue boxes represent the switching offices and their connection with other switching offices. The black lines connecting the switching offices represents the permanent link between the offices. When a connection is requested, links are established within the switching offices as denoted by white dotted lines, in a manner so that a dedicated circuit is established between the communicating parties. The links remains as long as communication continues.
It is suitable for long continuous transmission, since a continuous transmission route is established, that remains throughout the conversation.
The dedicated path ensures a steady data rate of communication.
No intermediate delays are found once the circuit is established. So, they are suitable for real time communication of both voice and data transmission.
Circuit switching establishes a dedicated connection between the end parties. This dedicated connection cannot be used for transmitting any other data, even if the data load is very low.
Bandwidth requirement is high even in cases of low data volume.
There is underutilization of system resources. Once resources are allocated to a particular connection, they cannot be used for other connections.
Time required to establish connection may be high.