Packet switching

Packet switching is a method for sending data whereby the data is divided in packets. Each packet is given a header containing information of the destination. Each packet is forwarded through the network to the destination using this information. At the destination the data has to be reassembled from the received packages.

There are two common packet switching methods in use:

• Datagram Packet Switching:
  Each packet is forwarded independently based on the destination address. Routing decisions are made dynamically, so each packet may follow a different route and thus the packages may arrive out of order.
• Virtual Circuit Packet Switching:
  A route is set up prior to packets being sent. The packets will all follow this route. This makes the routing through the network very easy and the packages will be received in the correct order.

Packet-switched networks were originally designed to overcome the inherent weakness of sending data over the analogue circuit switched network. Circuit switching is not very efficiënt for small messages and the analogue circuits make the data subject to noise and errors.

The biggest packet switched network is the internet. The internet uses the datagram packet switching method. X.25 is based on virtual packet switching.