Connection-Oriented Network Service

Connection-Oriented Network Service (CONS) is a service provided by the Open Systems Interconnection (OSI) network layer that establishes a virtual circuit for data exchange. It is one of the two primary OSI network-layer services, the other being Connectionless-mode Network Service (CLNS). CONS was largely influenced by X.25, and is formalized in the ISO standards ISO 8208 and ISO 8878,¹² but has been generalized and formalized, with adjustments to addressing, flow control, and error-handling mechanisms to conform to OSI standards.

Protocols providing CONS

Some protocols that provide the CONS service:

X.25, as specified in ITU-T Recommendation X.223 is a Public Data Network protocol that provides the Connection Oriented Network Service as described in ITU-T Recommendation X.213.
Signalling Connection Control Part (SCCP), as specified in ITU-T Recommendation Q.711 is a Signaling System 7 protocol that provides the Connection Oriented Network Service as described in ITU-T Recommendation X.213.
Service Specific Connection Oriented Protocol (SSCOP), as specified in ITU-T Recommendation Q.2110 is an Asynchronous Transfer Mode protocol that provides the Connection Oriented Network Service as described in ITU-T Recommendation X.213.

References

[1] ISO/IEC 8208:2000 Information technology — Data communications — X.25 Packet Layer Protocol for Data Terminal Equipment.

[2] ISO/IEC 8878:1992 Information technology — Telecommunications and information exchange between systems — Use of X.25 to provide the OSI Connection-mode Network Service.

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