ISO/IEC 8473-2:1996

Overview

ISO/IEC 8473-2:1996 specifies how a local area network conforming to ISO/IEC 8802 can be used as a subnetwork to provide the abstract underlying service for the connectionless-mode network protocol (CLNP) defined in ISO/IEC 8473‑1. Part of the ISO/IEC 8473 series, this part defines the subnetwork dependent convergence function (SNDCF) that maps between CLNP’s network-layer assumptions and the ISO/IEC 8802 logical link control (LLC) services offered by LANs.

Key topics and requirements

• Subnetwork Dependent Convergence Function (SNDCF): Defines the mapping of CLNP SN-UNITDATA primitives to subnetwork-specific UNITDATA primitives and back, for both connectionless- and connection-mode subnetworks.
• Use of ISO/IEC 8802 LLC: Specifies that the unacknowledged connectionless-mode service provided by LLC Class 1 (and Class 2’s connectionless mode) is used to supply the CLNP underlying service.
• Service data unit (SDU) size: The underlying service must support a minimum SDU size of 512 octets; SNDCF must handle segmentation where subnetworks have smaller PDUs.
• Primitives and addressing: Mapping involves primitives such as DL-UNITDATA with parameters (DL-Source-Address, DL-Destination-Address, DL-Priority, DL-Data). LAN station addresses are seven-octet values (six-octet MAC + one-octet LLC SAP).
• Protocol identification: Data received with protocol identification for ISO/IEC 8473 must be processed per ISO/IEC 8473‑1; other protocol IDs should be ignored.
• Conformance testing support: Annex A supplies a PICS (Protocol Implementation Conformance Statement) proforma - normative - to document implemented capabilities and options for conformance and interoperability testing.

Applications and who uses it

• Network protocol implementers building CLNP stacks that operate over IEEE 802 LANs.
• LAN and network equipment manufacturers (switches, NICs) that must support SNDCF behaviors and addressing conventions.
• System integrators and network architects designing OSI-layered interconnection across Ethernet/802 networks.
• Test labs and QA teams performing conformance testing and interoperability validation using the provided PICS proforma.
• Organizations maintaining or migrating legacy OSI/CLNP deployments where standardized CLNP-over-802 behavior is required.

Related standards

• ISO/IEC 8473-1: CLNP protocol specification
• ISO/IEC 7498-1: OSI Basic Reference Model
• ISO/IEC 8348: Network service definition
• ISO/IEC 8648: Network layer internal organization
• ISO/IEC 8802-2: LLC (logical link control)
• ISO/IEC 9646-1: Conformance testing methodology

ISO/IEC 8473-2 is essential when you need a standards-based mapping of CLNP to IEEE 802 LANs, ensuring predictable addressing, SDU handling, and a documented basis for conformance and interoperability testing.