Overview
ISO/IEC 8073:1997/Amd 1:1998 is an important amendment to the international standard ISO/IEC 8073:1997, titled Information technology - Open Systems Interconnection - Protocol for providing the connection-mode transport service. This amendment focuses on relaxing class conformance requirements and enhancing the protocol's ability to negotiate expedited data service features. Developed by ISO in collaboration with IEC and ITU-T, this amendment provides more flexible implementation options for users of the OSI transport protocol, particularly those who do not require full protocol functionality such as expedited data or operation over Connection-Oriented Network Service (CONS).
Key Topics
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Relaxation of class conformance requirements
The amendment introduces optional relaxations allowing implementations that do not need to support expedited data or operate over CONS to still be considered conformant. This enhances compatibility and reduces complexity for specific use cases.
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Expedited data service feature negotiation
Expedited data transfer is made optional, facilitating systems to negotiate this feature according to their needs without mandatory implementation. This adaptability is crucial for diverse network environments.
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Class conformance options
- Class 0 (basic transport service)
- Class 2 (supports expedited data optionally)
- Class 4 (operates over Connectionless Network Service (CLNS))
Implementers can choose to support one or multiple classes depending on their networking requirements.
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Interworking and protocol flexibility
The amendment outlines that full interworking between different transport classes is achievable if both Classes a) (Class 0 or 2 over CONS) and b) (Class 4 over CLNS) are implemented. This ensures broad interoperability across diverse OSI environments.
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Modification of transport protocol tables and clauses
Several tables and clauses within the standard, including Clause 8, Subclauses 12.2.3.2, 14.2, 14.3, 14.4, and annexes C.6.2 through C.10, are updated to reflect these changes. These modifications handle the status and negotiation of expedited data transfer and transport class conformance.
Applications
ISO/IEC 8073:1997/Amd 1:1998 is especially relevant in:
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Network protocol implementations
Developers of transport layer protocols in OSI networks can utilize this amendment to implement streamlined and flexible transport services tailored to specific application needs.
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Telecommunications systems
Systems requiring reliable connection-mode transport but not necessarily all protocol features can maintain conformance more easily, optimizing system resource use.
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Distributed application services
Applications that communicate via OSI transport protocols can benefit by negotiating supported features more flexibly, leading to improved compatibility and efficiency.
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Legacy and resource-constrained environments
The option to relax expedited data and CONS operation requirements enables implementations on devices or infrastructures that have limited capacity or do not require full OSI transport features.
Related Standards
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ISO/IEC 8073:1997
The original fourth edition of the protocol standard providing the foundation for transport service specifications.
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ITU-T Recommendation X.224
This amendment corresponds directly with ITU-T Rec. X.224/Amd.1, ensuring harmonization between ITU-T telecommunications recommendations and ISO/IEC standards.
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Open Systems Interconnection (OSI) reference model standards
ISO/IEC 8073 is part of the OSI suite of standards defining layered network communication protocols.
Keywords: ISO/IEC 8073, OSI transport protocol, connection-mode transport service, expedited data transfer, class conformance relaxation, CONS, CLNS, transport layer protocol, network interconnection, ITU-T X.224, international information technology standards.