Overview
ISO 21806-15:2021 specifies the conformance test plan (CTP) for the lean application layer of Media Oriented Systems Transport (MOST), a synchronous time-division-multiplexing (TDM) network used in road-vehicle multimedia and infotainment systems. The document defines conformance test cases (CTCs) for both root nodes and remote nodes, verifying behaviour required by ISO 21806-14. Interoperability testing is explicitly out of scope.
Key topics and requirements
- Purpose: define a standardized test plan to confirm that implementations of the MOST lean application layer meet specified requirements.
- Test scope: conformance test cases for these categories:
- Network startup
- Network shutdown
- Network events
- Node discovery
- Connection management
- Test roles and topology:
- Test set-up uses an Upper Tester (UT) and Lower Tester (LT) split into LT pre-IUT and LT post-IUT.
- LT post-IUT includes a listen-only node to monitor network activity.
- Root node acts as TimingMaster; remote nodes act as TimingSlave.
- Test case examples (node-specific CTCs found in the standard):
- Network startup/shutdown tests for root and remote nodes
- Unlock robustness and critical unlock tests
- Signature handling: valid, unknown, duplicate signature tests
- Connection management and welcome/error reaction tests
- Remote node reset and node position address checks
- Conformance framework: test design and terminology follow ISO/IEC 9646-1 methodology and OSI service conventions. Timer naming and deadlock prevention are covered and refer to ISO 21806-14 for protocol specifics.
- Practical test constraints: CTPs are independent; testers should follow manufacturer cooling guidance to avoid over-temperature during test execution.
Applications and users
Who uses ISO 21806-15:
- Automotive ECU and infotainment device manufacturers implementing the MOST lean application layer.
- Conformance test laboratories that certify compliance to ISO 21806-14 implementations.
- Automotive Tier‑1 suppliers and integrators validating node behaviour (root and remote).
- Tool vendors building MOST conformance test suites and automated test systems.
Why it matters:
- Ensures consistent, repeatable verification of lean application layer behaviour.
- Helps reduce integration issues by enforcing standardized conformance checks prior to system integration.
Related standards
Keywords: ISO 21806-15, MOST, lean application layer, conformance test plan, CTP, conformance test cases, root node, remote node, TDM network, automotive infotainment.