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CTM: The technique of sending data across the network is known as Switching technique. The three types
of techniques used are circuit switching, packet switching and message switching.

Circuit Switching

This provides end-to-end connection between two computers. Circuit switching is established
usually in a telephone network where one person is making a call and another is receiving a call.
In telephone system, the communication must be established between the two participants, i.e.,
the sender and the receiver. The circuit is established between these two participants before the
transfer of data takes place.

Receiver Caller

Fig. 8.6: Circuit Switching

In this technique, the entire link remains dedicated and no other user can use it even if the path
remains idle. The following actions take place during circuit switching:
1. A request signal is sent by the sender to set up the connection with the receiver. It establishes
a physical connection between the two participants.
2. All intermediate nodes are identified. These nodes are also called switching nodes.

3. If the destination node is available, it sends back the acknowledgement of receiving a signal.
Hence, data transmission begins.
4. When the data transmission is complete, the call can be terminated.

CTM: Circuit switching is a connection-oriented service. In this technique, there is a dedicated link between
the sender and the receiver and no other call can be made during this link, even if the link remains idle.

Packet Switching

In packet switching technique, the entire data is divided into small fragments called packets. Each
packet is of a fixed size, usually 128 bytes or 512 bytes. Packet switching is similar to post office
operation. Each packet has a source address as well as destination address (IP address) for being
Computer Science with Python–XII 8.8 follows different routes and, therefore, the packets are delivered in a random order at the
transmitted, in the same way as a postman delivers a letter to a specific destination address.
As there is no direct connection established between the sender and the receiver, each packet

destination address. It is the TCP protocol which then arranges all received packets in a sequential
order. During the transfer of packets, each packet has to pass through several intermediate nodes,
so each intermediate node checks for destination IP address. If the packet matches with the node
address, it is received; otherwise it is passed on to the next node until it reaches the destination IP
address.