ISO 17987-2:2025

Overview

ISO 17987-2:2025 - Road vehicles - Local Interconnect Network (LIN) - Part 2: Transport protocol and network layer services defines a transport protocol and network-layer services specifically for LIN-based vehicle networks. The document specifies an unconfirmed communication transport layer with a standardized API to support both normal and diagnostic application-layer messages on LIN sub-bus clusters. It is designed to enable diagnostics and multi-frame message transport on LIN networks while minimizing load on the commander node and enabling diagnostic capability on responder nodes.

Key technical topics and requirements

• Transport layer services and API: Standardized interface for transporting data contained in one or more frames; supports single-frame and multi-frame (segmented) transmissions.
• Protocol Data Units (PDUs): Definitions for SF (Single Frame), FF (First Frame), CF (Consecutive Frame) N_PDU types and mapping to the LIN data link layer.
• Protocol Control Information (N_PCI): Field definitions used to identify frame types and control multi-frame transfers.
• Network layer services and primitives: Service format and primitives such as N_USData.request, N_USData.confirm, N_USData.indication and N_USData_FF.indication for interaction with higher layers.
• Timing and error handling: Network-layer timing constraints, timeouts and error handling rules for reliable transport over LIN.
• Network management: Wake-up and go-to-sleep procedures, LIN node communication state diagram and cluster wake/sleep behavior.
• Diagnostic support: Diagnostic classes, response-pending handling, scheduling, and transmission handler requirements for commander and responder nodes.
• Data link layer integration: Service parameters and L_Data.request/confirm/indication mapping required to carry N_PDUs on LIN.
• Node capability and plug-and-play: LIN Node Capability Language (NCL) and Node Capability File (NCF) concepts for describing node capabilities and supporting plug-and-play workflows.

Practical applications and who should use this standard

ISO 17987-2:2025 is intended for:

• Automotive OEMs and Tier‑1 suppliers designing LIN clusters and sub-networks.
• ECU firmware engineers implementing LIN transport and network layers.
• Diagnostic tool developers and integrators who need LIN diagnostic transport compatible with ISO 14229-2 (UDS) and backbone diagnostics (e.g., CAN/ISO 15765-2).
• System architects aiming to extend backbone diagnostic capabilities to LIN sub-buses while keeping commander load low.
• Suppliers of LIN node stacks and middleware that require a standardized API and PDU definitions.

Practical uses include transporting multi-frame diagnostic messages over LIN, enabling responder-side diagnostics, designing robust wake/sleep behavior for low-power clusters, and creating plug‑and‑play node descriptions (NCL/NCF).

Related standards

• ISO 14229-2 (UDS service primitive interface) - referenced for service primitives and diagnostic interoperability.
• ISO 15765-2 (CAN transport protocol) - messages and PDUs are aligned/very similar to support consistent diagnostic behavior across backbone and LIN sub-buses.

Keywords: ISO 17987-2:2025, LIN transport protocol, Local Interconnect Network, LIN diagnostics, transport layer, N_PDU, N_PCI, NCL, NCF, ISO 14229-2, ISO 15765-2.