Circuit Switching in Networking
In Circuit Switching, a dedicated path is established between two communicating nodes before actual data transfer begins. The path means that connected sequence of physical links in which logical channel is dedicated to the connection.
Example: Telephonic Communication.
Phase of Circuit Switching :
There are three phases of circuit switching.
Circuit Establishment :
In circuit switching, data transfer can’t start automatically, before data transfer, a dedicated link is to established end-to-end. At first, the sender sends a request for connection to its attached switch. The switch depending on the destination address and the condition of traffic routes the connection request to the next switch. The second switch also does the same work. This process goes on until a switch is reached with which the destination node is connected directly. The last switch sends the connection request then it sends an acknowledgment signal to the sender. The time required for circuit establishment is 2-10 seconds depending on the network and distance between the endpoints.
Data Transfer :
Once the connection is established, the data can be transferred from one sender to receiver. Generally, the connection is full duplex. In that case, the data can be exchanged both ways simultaneously. Data may be digital or analog depending on the network architecture. Data are exchanged in a block and sent continuously. No routing or other controlling mechanisms are required during data transfer.
Circuit Disconnect :
The circuit may be disconnected by either end and the disconnection information is transferred from one end to another following the dedicated path. The intermediate switches after passing the disconnection information release the path. In this way, the dedicated path becomes free and it can be used for a new connection.