Sunday, April 15, 2007

Packet Switching: Circuit Switching’s Nemesis… Well alternative, but “Nemesis” is more dramatic and funnier to say

Packet Switching
Circuit Switching’s Nemesis… Well alternative, but “Nemesis” is more dramatic and funnier to say

Packet switching is a WAN (Wide Area Network) technology of protocols that divide messages/data into packets (units of information carriage), then route them individually to its destination. During the transfer of the packets, the packets can be delivered altogether or independently of each other through different routes. Once at its destination, they are recompiled into the original message.

To prevent unpredictably long delays and ensure that the network has a reliably fast transit time, a maximum length is allowed for each packet. This is why a message would be submitted to the “transport layer” first, and then divided by the “transport protocol” entity into a number of smaller packet units before transmission. The end result is a reassembled message at the destination. This method of transferring data optimizes bandwidth available in a network to minimize the transmission latency (time it takes for data to pass across a network), and to increase the strength of communication.

The costs to customers using packet switching are lower than point-to-point lines because packet switching is more efficient in using a network infrastructure. The carrier can create virtual circuits between customers’ sites through its packet routing protocols. The section of the network that is shared is often referred to as a “cloud.” Packet switching is also called connectionless networking because no physical connections, like circuit switching, are established.

Packet-switched networks using satellite or terrestrial radio as the transmission medium are known as packet satellite or packet radio networks, respectively. These networks were designed for covering large areas for mobile stations, or for applications that benefit from the availability of real-time information at several locations.

Handling messages of different lengths was always done very well by packet switching, as well as different priorities when quality of service (QoS) attributes were included. Packet switching was originally designed for data, but lately packet networks are becoming the norm for voice and video as well.

The most well known use of packet switching is the Internet, which is often referred to as a “Datagram Packet Switching Network.” The first international standard for wide area packet switching networks was X.25. Other examples of packet switching are Ethernet, frame relay, and mobile phone technologies such as GPRS and I-mode.

Already, we can see that there is more flexibility with packet switching than with circuit switching. The Internet, which is a widely used infrastructure, can be used efficiently without the need for a point-to-point connection that circuit-switching networks require.

Come back later this week as I compare circuit switching and packet switching.