Connectionless

In a packet switched network, Connectionless mode transmission is transmission in which each packet is encoded with a header containing a destination address sufficient to permit the independent delivery of the packet without the aid of additional instructions.

The distinction between connectionless and connection-orientated transmission typically takes place at the network layer.

A packet transmitted in a connectionless mode is frequently called a datagram.

In connectionless mode transmission of a packet, the service provider usually cannot guarantee there will be no loss, error insertion, misdelivery, duplication, or out-of-sequence delivery of the packet. However, the risk of these hazards may be reduced by providing a reliable transmission service at a higher protocol layer, such as the Transport Layer of the Open Systems Interconnection--Reference Model.

Source: older version from Federal Standard 1037C