Overview
ISO 21806-7:2020 - "Road vehicles - Media Oriented Systems Transport (MOST) - Part 7: Data link layer conformance test plan" specifies a structured conformance test plan (CTP) for the data link layer of MOST networks. MOST is a synchronous time-division-multiplexing (TDM) communication technology widely used in automotive multimedia and infotainment systems. This part of the ISO 21806 series defines the conformance test cases (CTCs) and the test set‑up required to verify that an implementation conforms to the data link layer requirements in ISO 21806-6. Interoperability testing is explicitly out of scope.
Key topics and technical requirements
- Conformance test plan (CTP): Defines test architecture, roles and procedures for executing CTCs. Test set‑up uses an Upper Tester (UT) and a Lower Tester (LT) split into LT pre‑IUT and LT post‑IUT with a clear description of IUT (implementation under test) roles.
- CTC categories: The document specifies CTCs covering:
- Network frames (preamble, bit order, node counters)
- Allocation channel (allocation words, SOAF, reporting, TimingMaster/TimingSlave behaviors)
- Protected system channel (size/location, CRC reaction, node counters, system flags)
- Timestamp channel
- Flow control (target addressing, PACK byte behavior)
- Cyclic redundancy check (CRC) (CRC handling and acknowledge)
- Arbitration (participation rules, WAIT/Arb handling)
- Default packet channel
- Test set‑up and execution: Includes UT/LT roles, power monitoring (to detect node sleep states), and environmental considerations (avoid over‑temperature per manufacturer guidance).
- Normative references: Integrates conformance testing methodology from ISO/IEC 9646‑1 and links to ISO 21806‑1 and ISO 21806‑6 for layer definitions and normative requirements.
Practical applications
- Use ISO 21806-7:2020 to develop and validate test suites, test tools, and lab procedures that verify MOST data link layer conformance.
- Integrate CTCs into supplier validation plans to ensure device compliance before vehicle integration.
- Apply in certification and quality assurance workflows to reduce integration defects for infotainment, audio/video streaming, and packet-data components on MOST networks.
Who should use this standard
- Automotive OEMs and Tier‑1/Tier‑2 suppliers implementing MOST nodes
- Test laboratories and conformance test tool developers
- System integrators validating data link layer behavior
- Certification bodies assessing MOST conformance
Related standards
Keywords: ISO 21806-7:2020, MOST, data link layer, conformance test plan, CTC, TDM network, automotive infotainment, CRC, flow control, arbitration.
Open preview (PDF)Road vehicles — Media Oriented Systems Transport (MOST) — Part 7: Data link layer conformance test plan
