Question

What is a packet switch? What is a circuit switch? What is a message switch? Give two examples of packet-switched networks and explain how they work.

Answer 1

Packet Switching : - This is a communication techniques where no dedicated path for data transfer is specified. Here data are divided into small parts called packet and sent over the network. It can identify suitable route and get delivered by using alternative route if any route in it's path is down.

Circuit Switching :- The communications which have a dedicated path or circuit for communication is known as circuit switching. Circuit Switching mainly used in telephone network where a dedicated route follow three steps to complete full process i.e Circuit establishments, Data transfer and circuit disconnects. Although it is reliable but due to path dependency if any inconvenience happens in this dedicated path whole communication between this two node will be disconnected.

Message Switching :- In this switching method instead of establishing a dedicated physical line between the sender and the receiver, the message is sent to the nearest directly connected switching node. This node stores the message, checks for errors, selects the best available route and forwards the message to the next intermediate

Example of Packet switching is frame relay and IP. In packet switching, data are generally transferred using small sizes packets. The maximum length of the packet is 1000 octets. If a long message has to be send, then the message is broken up into series of packets of small sizes. The packet contains the user data and the control information that routes the packet from source to destination. The control information contains the information that is needed to route the packets throughout the network. At each node in the network, the packet is received and some information about it is stored in that node and passed to the next node. After received at destination small part of packets joined as per sequence maintained at sender end and create full message at receiver end.