Circuit Switching is a connection oriented technique for establishing the connection. Suppose A first make connection request packet called control packet (CP), which contain following.
Circuit switching was designed for voice communication. In telephone conversation for example, once a circuit is established it remain connected for duration of the session. Circuit switching creates temporary (dialled) or permanent (leased) dedicated link that are well suited to this type of communication.
Explanation:
Suppose A make connection with following path like A--V--W--X--Y--B decision is taken place at each router, that decision is routing decision when (CP) is reached at that router.
When the connection is established then the whole path is reserved for that particular transmission. This path is reserved until the whole transmission is not completed.
After that B make a connection confirm packet (CC) and send to A. (CC) does not contain any source address and destination address because path is already establish and (CC) packet will follow that path to reach A.
When A receive (CC) packet than it confirm that B is ready to receive data.
The time which is used to make circuit or connection is called circuit setup.
In circuit switching before sending message connection is establish. Handshaking is done before message sending.
Drawback of Circuit Switching:
✔ When circuit switching link are used for data transmission therefore the line is often ideal and its facilities wasted.
✔ A second weakness of circuit switched connection for data transmission is in its data rate. A circuit switched link creates the equivalent of a single cable between two device and there by assume a single data rate for both device. This assumption limits the flexibility and usefulness of a circuit switched connection for network interconnecting a variety of digital device.
✔ Third circuit switching is inflexible once a circuit has been established that circuit is the path which is reserved until all the message are not transferred.
✔ Utilisation of channel is poor.
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