Switching techniques
Switching techniques are used for transmitting data across networks.
Different types are :
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Circuit Switching
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Message Switching
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Packet Switching
Circuit Switching
- Circuit switching is the transmission technology that has been used since the first communication networks in the nineteenth century.
- First the complete physical connection between two computers is established and then the data are transmitted from the source computer to the destination.
- When a call is placed the switching equipment within the system seeks out a physical copper path all the way from the sender to the receiver.
- It is must to setup an end-to-end connection between computers before any data can be sent.
- The circuit is terminated when the connection is closed.
- In circuit switching, resources remain allocated during the full length of a communication, after a circuit is established and until the circuit is terminated and the allocated resources are freed.
Message Switching
- In this the source computer sends data or the message to the switching circuit which stores the data in its buffer.
- Then using any free link to the switching circuit the data is send to the switching circuit.
- Entire message is sent to the destination. It reaches through different intermediate nodes following the “store and forward” approach.
- No dedicated connection is required.
Packet Switching
- Conceived in the 1960’s, packet switching is a more recent technology than circuit switching.
- Packet switching introduces the idea of cutting data i.e. at the source entire message is broken in smaller pieces called packets which are transmitted over a network without any resource being allocated.
- Then each packet is transmitted and each packet may follow any rout available and at destination packets may reach in random order.
- If no data is available at the sender at some point during a communication, then no packet is transmitted over the network and no resources are wasted.
- At the destination when all packets are received they are merged to form the original message.
- In packet switching all the packets of fixed size are stored in main memory.
