ISO/IEC 8602:1995 - Overview
ISO/IEC 8602:1995 specifies the protocol for providing the OSI connectionless-mode transport service. This second edition (1995) cancels and replaces the 1987 edition and is identical to ITU‑T Recommendation X.234. The standard defines the procedures, message encodings and functional requirements needed for transport entities to exchange data and control information without establishing a transport connection.
What the standard covers
- Procedures for connectionless-mode transmission of data and transport protocol control information between peer transport entities.
- Rules for the correct interpretation of transport protocol control information.
- Encoding of Transport-Protocol-Data-Units (TPDUs), including the Unit Data (UD) TPDU used for connectionless transfers.
- Functional conformance requirements and a PICS (Protocol Implementation Conformance Statement) proforma for implementers.
- Annexes providing a state table, PICS proforma and checksum algorithms (informative).
Key technical topics and requirements
- Transport layer role: defines the service provided by the Transport Layer and its assumed network services.
- Support for operation over both connectionless and connection-oriented network services as defined in CCITT Rec. X.213 / ISO/IEC 8348.
- TPDU handling: TPDU transfer mechanisms, TPDU field definitions (e.g., length indicators), and checksum computation and verification procedures.
- Transport-service primitives and mappings to network-service primitives for both network service types.
- Conformance testing guidance and PICS proforma to document implementation claims per ISO/IEC 9646 series.
Practical applications and who uses it
- Network protocol designers and implementers building OSI-compliant transport-layer software that requires single‑access, low-overhead data transfer without connection setup.
- Vendors of embedded systems, routers, gateways, or legacy OSI stacks that must interoperate with existing OSI transport services.
- Test houses and compliance teams using the PICS proforma for protocol conformance assessment.
- Organizations maintaining or migrating legacy telecommunications and industrial control systems that rely on OSI connectionless transport semantics.
Related standards
- ITU‑T Recommendation X.234 (identical text)
- ISO/IEC 8072 / ITU‑T X.214 - Transport service definition
- ISO/IEC 8348 / CCITT X.213 - Network service definition
- ISO/IEC 7498-1 / ITU‑T X.200 - OSI Reference Model (basic model)
- ISO/IEC 9646 series / CCITT X.290–X.291 - Conformance testing methodology and PICS guidelines
Keywords: ISO/IEC 8602, OSI connectionless-mode transport service, TPDU, UD TPDU, transport protocol, transport layer, PICS, checksum, X.234, connectionless transport.