The terms ‘connectionless’ and ‘connection-oriented’ are sometimes used in confusing ways. Let’s set the record straight in a way that would satisfy the demands of a network expert.
Connectionless And Datagram Mean The Same Thing
A connectionless protocol (or protocol layer) does not have a sequence number and acknowledgment scheme. That’s all. No sequence numbers mean that a protocol is ‘connectionless’. It could also be referred to as a ‘datagram’.
Connection-Oriented And Reliable Mean The Same Thing
A connection-oriented protocol (or protocol layer) has sequence numbers and an expected acknowledgment process. If acknowledgments are not received then retransmission will occur. In this way, a connection-oriented protocol can guarantee delivery of data. That’s all. If a protocol has sequence numbers then it’s ‘connection-oriented’. It could also be referred to as a ‘reliable’ protocol.