Overview
ISO 21806-5:2020 defines the Conformance Test Plan (CTP) for the transport layer and network layer of Media Oriented Systems Transport (MOST) networks used in road vehicles. The standard specifies how to design and implement conformance test cases (CTCs) to verify that MOST implementations meet the transport- and network-layer requirements defined in ISO 21806-4. It is focused on conformance testing (not interoperability) for MOST, a synchronous time-division-multiplexing (TDM) network widely used for automotive multimedia and infotainment systems.
Key topics and technical requirements
- CTP scope and organization
- Test case structure, conventions, and prerequisites for conformance testing.
- Reference to conformance methodology in ISO/IEC 9646-1.
- CTC categories
- Network layer services - verification of service primitives and expected behaviors.
- Data transport mechanism - tests for packet and segmented transfers, buffering and error handling.
- Dynamic behaviour of a node - start-up/wake-up, shutdown, timing master/slave roles, and sleep states.
- Test set-up and roles
- Standardized test topology with an Upper Tester (UT) and Lower Tester (LT); the LT is split into LT pre‑IUT and LT post‑IUT and includes a listen‑only node for logging.
- The Implementation Under Test (IUT) may act as TimingMaster or TimingSlave, or be physically disconnected for specific tests.
- Test requirements include power monitoring to detect transitions (e.g., s_NetInterface_Sleep).
- Representative CTCs (examples from table of contents)
- Wake-up tests (TimingMaster/TimingSlave).
- Unlock, short unlock and sudden signal-off tests.
- Segmented transfer tests (rejection, sending, segmentation error, buffer and parallel reception).
- Measurement and conformance
- Annex A addresses measurement uncertainty for individual CTCs.
- Normative references include ISO 21806-1, -2, -4 and ISO/IEC 9646-1.
Practical applications
- Implementing and validating transport and network layer functionality in MOST nodes for automotive infotainment, audio/video streaming, and control data.
- Developing conformance test tools and automated test benches for supplier qualification and product verification.
- Ensuring device behavior under dynamic conditions (wake-up, segmented transfers, timing roles) meets ISO requirements to reduce integration risk.
Who should use this standard
- Automotive ECU and multimedia device manufacturers
- Conformance and test laboratory engineers
- System integrators and validation teams
- Test tool and middleware developers working with MOST networks
Related standards
Keywords: ISO 21806-5:2020, MOST, transport layer, network layer, conformance test plan, CTP, CTC, automotive infotainment, TDM network.