Connectionless Protocols

Connectionless protocols, in contrast, allow data to be exchanged without setting up a link between processes. Each unit of data, with all the necessary information to route it to the intended destination, is transferred independent of other data packets and can travel over different paths to reach the final destination. Some data packets might be lost in transmission or might arrive out of sequence to other data packets.

UDP is a connectionless protocol. It is known as a datagram protocol because it is analogous to sending a letter where you don't acknowledge receipt.

Examples of applications that use connectionless transport services are broadcasting and tftp. Early implementations of NFS used UDP, whereas newer implementations prefer to use TCP.