Connection-oriented
From Hill2dot0
Any communication that has three distinct phases:
- connection establishment or setup
- data or information transfer
- connection termination or release.
During the connection establishment phase, a communication relationship is established. In a circuit or virtual circuit network, this will include the establishment of the circuit or virtual circuit. Usually there is also an end-to-end agreement by the users of the connection. In a datagram network, only this latter relationship exists. Establishing a communication relationship can be as simple as just agreeing to communicate, or it could be as complex as negotiating sophisticated communication parameters such as how and if acknowledgements will be provided, maximum packet or frame sizes, flow control parameters, and sequence numbers.
During the information transfer phase, information is transferred according to the rules or parameters determined during the connection establishment phase.
During the connection termination phase, the communication relationship is ended. This typically involves notification to either end that the relationship is ended, and release of any resources devoted to the communication (e.g., circuits, virtual circuits, buffers, ports, etc.)
The classic example of a connection-oriented service is the Public Switched Telephone Network (PSTN). Before you can have a conversation with someone across this network, you have to pick up the phone, dial a number, wait for the ring, and have it answered at the far end. All of these are part of the connection establishment phase. Once the connection is complete, you can talk: the information transfer phase. Once the communication is over you hang up the phone and the network releases all of the resources devoted to your call. This is the connection release phase.
In data networks, protocols like the Transmission Control Protocol (TCP), frame relay, and Asynchronous Transfer Mode (ATM) are all examples of connection-oriented protocols.
Although acknowledgement, flow control, sequencing, and recovery from loss is most often associated with connection-oriented protocols, that does not mean that all such protocols do these things. Frame relay, for example, provides no error recovery, flow control, or acknowledgement mechanism.
Connection-oriented communications should be contrasted with connectionless communication.
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| Connectionless vs. connection-oriented communication
