Network switching is the process of transmitting data packets from the source to the destination through a number of intermediate network nodes. Here, each node controls or switches data packets to the next node towards the destination. When data comes on a node it is called ingress, and when data goes out of a node it is called egress.
The two broad level switching methods are connection oriented switching and connectionless switching.
Connection – oriented Switching : In connection – oriented switching, a dedicated path is established between the source and the destination before data switching. Once this path is established, the entire message sent through this route.
Connectionless Switching : In connectionless switching, no path is established prior to data switching. Each data unit has complete address information and is individually routed from the source to the destination using forwarding tables of the nodes.
The three common switching techniques are circuit switching, packet switching and message switching −
Circuit Switching : Here, a dedicated path is established between the source and the destination and then all the message is sent over this route. It is an example of connection – oriented switching method.
Packet Switching : The entire message is broken down into small data packets each of which has switching information in its header. The packets are then individually routed from the source to the destination. The destination node reassembles out-of-order packets according to header information. It is an example of connectionless switching.
Message Switching : It is a combination of circuit switching and message switching. Here, the entire message is considered as a data unit and is routed from one node to another in a connectionless manner.