2.3 Packet Switching with Datagrams

In packet switching mode, the message which is to be transmitted from participant A to B is divided into packets. Each packet is provided with destination and control information and is seperately transmitted via the network.

Packet switching can be realized in two different operational modes: connectionless and connection-oriented.

In the connectionless or datagram mode, each packet of the communication process is provided with destination and control information as well as a sequence number. The packets are sent to the destination independent from each other. Thus, packets can take different paths across the network and possibly overtake each other. By using a sequence number for each of the packets, the receiver can reorder the packets and reassemble them to the original message. The datagram packet switching mode is also used in the Internet.