Connection-oriented systems (e.g., POTS, ISDN, X.25, TCP, ATM) establish connections between a pair of communicating systems. In the phone system a connection is associated with a physical dedicated link. In ATM, a connection is a virtual link (circuit) which is characterized by a Class of Service which it must deliver to the users of the circuit (e.g., a constant bit rate service for uncompressed voice over ATM).
Connection oriented systems support a set of protocols for transmission of data and another set of protocols for establishing connections (e.g., SS7, Q2931). End systems request that the network establish a connection by sending messages to the network over a pre-defined control channel (circuit). Once the network has established a data channel (circuit) per the request, data is forwarded over that channel. Connections may be established by a network manager as Permanent Virtual Circuits (PVCs) or may be dynamically established by system software as Switched Virtual Circuits (SVCs).
Connection oriented systems support a set of protocols for transmission of data and another set of protocols for establishing connections (e.g., SS7, Q2931). End systems request that the network establish a connection by sending messages to the network over a pre-defined control channel (circuit). Once the network has established a data channel (circuit) per the request, data is forwarded over that channel. Connections may be established by a network manager as Permanent Virtual Circuits (PVCs) or may be dynamically established by system software as Switched Virtual Circuits (SVCs).
