Packet switching is a digital network transmission process in which data is broken into suitably-sized pieces or blocks for fast and efficient transfer via different network devices. When a computer attempts to send a file to another computer, the file is broken into packets so that it can be sent across the network in the most efficient way. These packets are then routed by network devices to the destination.
There are two major modes of packet switching:
- Connectionless Packet Switching: Each packet contains complete addressing or routing information and is routed individually. This can result in out-of-order delivery and different paths of transmission, depending on the variable loads on different network nodes (adapters, switches and routers) at any given time. Also known as datagram switching.In connectionless packet switching, each packet has the following information written in its header section:
- The destination address
- The source address
- Total number of pieces
- The sequence number (Seq#) needed to enable reassembly
After reaching the destination through different routes, the packets are rearranged to form the original message. - Connection-Oriented Packet Switching: Data packets are sent sequentially over a predefined route. Packets are assembled, given a sequence number and then transported over the network to a destination in order. In this mode, address information is not required. Also known as virtual circuit switching.
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