Theme: Data transmission based on channel and packet switching

What is Packet Switching?

Introduction:
In packet switching network unlike CS network, it is not required to establish the connection initially. The connection/channel is available to use by many users, but when capacity or number of users increases then it will lead to congestion in the network. Packet switched networks are mainly used for data and voice applications requiring non-real time scenarios.

In packet switching, station or IP device breaks long message into small size packets and inserts headers as per predefined formats of TCP/IP stack. These headers contain many useful informations including source address, destination address, length of packet, port number, protocol field, checksum etc. Packets are transmitted sequentially. Packets are assembled at the receiver with the help of sequence numbers. In packet switching, packets are handled in two ways viz. datagram and virtual circuit. In datagram type, each packet is treated independently. Packets can take up any route between source PC and destination PC. Packets may arrive out of order and may even not reach destination in some cases. In virtual circuit type, pre-planned route is established before the transmission of packets. The Call request and call accept messages are used as handshake mechanism. In this type, each packet contains VCI (virtual circuit identifier) instead of the destination IP address. In this type, routing decisions for each packet are not needed as it is made only once for all the packets using virtual circuit.

Refer circuit switching vs packet switching which mentions difference between circuit switching and packet switching types.