There are three types of switching networks-
- Circuit Switched network
- Message Switched network
- Packet Switched network
Circuit Switched Network: – In Circuit Switched Network, once a connection is made between two nodes, it is maintained until one of them terminates it. This can be said in another way that the connection is dedicated to the communication between the two parties. Circuit switching is common in the telephone system because the channel assigned to one telephone connection cannot be used by another.
A circuit Switched network is showing in fig-1 in fig-1 node A has determined that C is a better choice than B in the route from A to F., therefore, node A connects to node C. Node C, in turn Proceeds similarly. It might Select node F, or it Might decide to go node E. Again, cost and exiting connections affect the choice. In this case, node C connects to node E. Lastly, E connects to F. The Connection is made, and node F may be willing to accept it. If node F does not respond, Node A terminates the request.
A circuit Switched network is showing in fig-1 Circuit swathing needs that the route be determined and the connection made before any information sent. In addition, the network maintains the connection until a node terminates it. This type of connection is most useful when the communications between the two nodes are continuous, that is when node A says something and node F hears almost immediately, with virtually no transmission delay.
Message Switched Network: – A Message Switched Network is shown in Fig-2, a network uses message switching to establish a route when a message (a unit of information) is transmitted. For ex. Node A transmits the message, “will you go to the college with me?” to node F. Node A attaches the location or address of F to the message and looks for the first node in the route. As Fig 2 shows, node A choose node C. node A transmits the message along with the address of F to C.
The message is stored there temporarily while logic looks for another node. It transmits the message to node E, where it again stored temporarily. Lastly, logic at E locates node F and transmits the message to its final destination. Since the message is stored in its entirety at each node, networks that use this method are also Known as Store-and- forward networks.
Packet Switched Network: – Packet Switched Network minimizes the effects of problems caused by long message on message switched networks. In packet switched networks, if the message is long, it is divided into smaller units called Packets. Their size is design dependent. Each packet contains its destination address or some other designator indicating where it should go and is routed there by network protocols. When the packets all arrive, they are reassembled. A physical connection between the two endpoints is not maintained. The smaller size of the packets facilitates the essential buffering at intermediate network nodes. In packet switched networks, two common routing methods are used, which are – datagram and virtual circuit.
In the datagram approach, each packet is sent independently. That is, networks protocols route each one as though it where a separate message. This permits routing strategies to consider the changing conditions within the network. Congestion on certain routes may cause rerouting.
In virtual circuit approach, networks protocols establish a route before transmitting any packets. They delivery of the packets using the same route ensure that the packets arrive in order and without error.