ISO 21806-7:2020

INTERNATIONAL ISO
STANDARD 21806-7
First edition
2020-09
Road vehicles — Media Oriented
Systems Transport (MOST) —
Part 7:
Data link layer conformance test plan
Véhicules routiers — Système de transport axé sur les médias —
Partie 7: Plan d'essais de conformité de la couche de liaison de données
Reference number
©
ISO 2020
© ISO 2020
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ii © ISO 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 2
4.1 Symbols . 2
4.2 Abbreviated terms . 2
5 Conventions . 2
6 CTP overview . 2
6.1 Test set-up . 2
6.2 Conformance test plan organisation . 4
7 CTP general information . 4
8 CTC specification . 5
8.1 Network frame CTCs . 5
8.1.1 CTC_7.1-1 – PREAMBLE test . 5
8.1.2 CTC_7.1-2 – General bit order test . 5
8.1.3 CTC_7.1-3 – Node counter bit order test . 6
8.2 Allocation channel CTCs. 7
8.2.1 CTC_7.2-1 – Allocation words . 7
8.2.2 CTC_7.2-2 – Start of Allocation Frame (SOAF) test . 7
8.2.3 CTC_7.2-3 – Reporting format test . 8
8.2.4 CTC_7.2-4 – TimingMaster clears the allocation word test . 9
8.2.5 CTC_7.2-5 – TimingMaster not arbitrating test . 9
8.2.6 CTC_7.2-6 – TimingSlave forwards allocation word test .10
8.3 Protected system channel CTCs .11
8.3.1 CTC_7.3-1 – Size and location test .11
8.3.2 CTC_7.3-2 – Reaction on CRC error test .12
8.3.3 CTC_7.3-3 – Node counter test .12
8.3.4 CTC_7.3-4 – TimingMaster visible nodes value test .13
8.3.5 CTC_7.3-5 – System flags test .13
8.4 CTC_7.4-1 – Timestamp channel frame test .14
8.5 Flow control CTCs .15
8.5.1 CTC_7.5-1 – Target address not matching test .15
8.5.2 CTC_7.5-2 – Modification of the PACK byte test .16
8.6 Cyclic redundancy check CTCs .17
8.6.1 CTC_7.6-1 – No reception of channel frame test .17
8.6.2 CTC_7.6-2 – CRC acknowledge test .18
8.7 Arbitration CTCs .19
8.7.1 CTC_7.7-1 – Only sending nodes participate test .19
8.7.2 CTC_7.7-2 – Copy Arb1 and WAIT test .19
8.7.3 CTC_7.7-3 – Copy Arb2 into Arb3 test .20
8.7.4 CTC_7.7-4 – Forward WAIT test .21
8.8 CTC_7.8-1 – Default packet channel test .22
Bibliography .23
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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on the ISO list of patent declarations received (see www .iso .org/ patents).
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expressions related to conformity assessment, as well as information about ISO's adherence to the
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iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 31,
Data communication.
A list of all parts in the ISO 21806 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved

Introduction
The Media Oriented Systems Transport (MOST) communication technology was initially developed at
the end of the 1990s in order to support complex audio applications in cars. The MOST Cooperation was
founded in 1998 with the goal to develop and enable the technology for the automotive industry. Today,
1)
MOST enables the transport of high quality of service (QoS) audio and video together with packet data
and real-time control to support modern automotive multimedia and similar applications. MOST is a
function-oriented communication technology to network a variety of multimedia devices comprising
one or more MOST nodes.
Figure 1 shows a MOST network example.
Figure 1 — MOST network example
The MOST communication technology provides:
— synchronous and isochronous streaming,
— small overhead for administrative communication control,
— a functional and hierarchical system model,
— API standardization through a function block (FBlock) framework,
— free partitioning of functionality to real devices,
— service discovery and notification, and
[2]
— flexibly scalable automotive-ready Ethernet communication according to ISO/IEC/IEEE 8802-3 .
MOST is a synchronous time-division-multiplexing (TDM) network that transports different data types
on separate channels at low latency. MOST supports different bit rates and physical layers. The network
clock is provided with a continuous data signal. ®
1) MOST is the registered trademark of Microchip Technology Inc. This information is given for the convenience
of users of this document and does not constitute an endorsement by ISO.
Within the synchronous base data signal, the content of multiple streaming connections and control
data is transported. For streaming data connections, bandwidth is reserved to avoid interruptions,
collisions, or delays in the transport of the data stream.
MOST specifies mechanisms for sending anisochronous, packet-based data in addition to control data
and streaming data. The transmission of packet-based data is separated from the transmission of
control data and streaming data. None of them interfere with each other.
A MOST network consists of devices that are connected to one common control channel and packet
channel.
In summary, MOST is a network that has mechanisms to transport the various signals and data streams
that occur in multimedia and infotainment systems.
The ISO standards maintenance portal (https:// standards .iso .org/ iso/ ) provides references to MOST
specifications implemented in today's road vehicles because easy access via hyperlinks to these
specifications is necessary. It references documents that are normative or informative for the MOST
versions 4V0, 3V1, 3V0, and 2V5.
The ISO 21806 series has been established in order to specify requirements and recommendations
for implementing the MOST communication technology into multimedia devices and to provide
conformance test plans for implementing related test tools and test procedures.
To achieve this, the ISO 21806 series is based on the open systems interconnection (OSI) basic reference
[1] [3]
model in accordance with ISO/IEC 7498-1 and ISO/IEC 10731 , which structures communication
systems into seven layers as shown
...