## Network types: circuit and packet switched network operation

| #### Most modern networks operate in what is called a circuit or packet switched mode. A circuit switched network is one where at the start of each complete message transaction (for example, a telephone call), the route through the network is identified, the correct links are switched in, and this configuration is held for the entire duration of the call.
#### A packet switched network, on the other hand, routes small chunks (packets) of the message, hopefully down the best route (least congested, least noisy, and so on) available at the time. |

#### Packet switched networks are able to 'optimize' the routing of data on a packet-by-packet basis and hence these systems are very attractive for ensuring the best use of the network capacity – particularly for unpredictable densities and duration of traffic such as Internet access. The protocol overhead for routing of individual packets, and for ensuring that packets arrive on time and in the right sequence when they have travelled by several different paths, makes the circuit switched approach more attractive for some applications such as voice traffic. There is, however, a trend towards using packet switched networks for voice also.