Overview
ISO/IEC 8072:1996 - Information technology - Open Systems Interconnection - Transport service definition defines the abstract Transport Service offered by the OSI Transport Layer to the Session Layer. Published as the third edition in 1996 (identical to ITU‑T Recommendation X.214), the standard specifies the externally visible behaviour of the transport service - not specific implementations - to support interoperable session and transport protocols.
Key topics and requirements
- Service abstraction: Defines the Transport Service in terms of primitives (actions/events), associated parameters, and valid primitive sequences.
- Connection-mode and connectionless-mode: Separate models and behaviours are defined for both connection-oriented (Transport Connection) and connectionless transport services.
- Phases and primitives:
- Establishment, data transfer (including expedited data), and release phases for connection-mode services.
- Data transfer and primitive sequences for connectionless-mode services.
- Detailed TS (Transport Service) primitives and parameters such as addresses (called, calling, responding), TS user‑data, and expedited data options.
- Quality of Service (QoS) parameters: Includes metrics and characteristics relevant to transport service quality - e.g., transit delay, residual error probability/rate, throughput, protection, priority and resilience. The standard describes how QoS is expressed and used when negotiating service behaviour.
- Behavioral sequences: Specifies valid sequences and relations of TS primitives at endpoints, including success/failure and rejection handling.
- Scope and conformance: Abstract service definition intended for use by session protocol designers and transport protocol implementers; conformance is achieved via protocols that fulfil this service definition.
Applications and who uses it
- Protocol designers: To design transport protocols that provide a well‑defined service to upper layers (Session Layer).
- Network architects and implementers: For specifying expected transport behaviour (connection setup, data transfer, QoS) when building interoperable systems.
- Vendor product teams: To ensure products conform to OSI transport service semantics for multi-vendor interoperability.
- Standards bodies and educators: As a reference for OSI layering, service definition conventions, and QoS parameterization in academic and standards contexts.
Related standards
Keywords: ISO/IEC 8072:1996, Transport service definition, OSI Transport Layer, TS primitives, connection-mode, connectionless-mode, Quality of Service, ITU‑T X.214.