ISO 21806-14:2021

INTERNATIONAL ISO
STANDARD 21806-14
First edition
Road vehicles — Media Oriented
Systems Transport (MOST) —
Part 14:
Lean application layer
Véhicules routiers — Système de transport axé sur les médias —
Partie 14: Couche d'application allégée
PROOF/ÉPREUVE
Reference number
ISO 21806-14:2021(E)
©
ISO 2021

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ISO 21806-14:2021(E)

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© ISO 2021
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Published in Switzerland
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ISO 21806-14:2021(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 3
4.1 Symbols . 3
4.2 Abbreviated terms . 3
5 Conventions . 3
6 Basic principles . 3
7 Node kinds . 4
7.1 General . 4
7.2 Root node . 4
7.2.1 General. 4
7.2.2 Lean network services . 5
7.2.3 Network descriptor . 5
7.3 Remote node . 6
7.4 Listen-only node . 6
8 Node addressing . 6
9 Data transport . 7
10 Network configuration . 7
10.1 General . 7
10.2 Network . 7
10.3 Node . 8
10.4 Path . 8
10.5 Coupling . 8
10.6 Streaming socket . 9
10.7 Network socket . 9
11 Network supervisor/application interface (NSAI) .10
11.1 Overview .10
11.2 Requests, responses, and events .11
11.2.1 Network startup and shutdown .11
11.2.2 Connection management .11
11.2.3 Diagnosis .11
12 Lean network services interface (LNSI) .12
12.1 Overview .12
12.2 Requests, responses, and events .14
12.2.1 Lean network services .14
12.2.2 Network startup and shutdown .14
12.2.3 Node discovery .14
12.2.4 Connection management .15
12.2.5 Diagnosis .15
13 Network management .15
13.1 Network startup and shutdown .15
13.2 Network events .15
13.2.1 General.15
13.2.2 End of network activity .16
13.2.3 Unlock and critical unlock .16
13.2.4 Network change event .16
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13.2.5 Source drop .16
13.3 Node discovery .16
13.3.1 General.16
13.3.2 Addresses .17
13.3.3 Scanning the network .17
13.3.4 Adding nodes to the network .18
13.3.5 Reset detection .21
13.4 Connection management .23
13.4.1 General.23
13.4.2 Sockets .24
13.4.3 Couplings .24
13.4.4 Paths .25
13.4.5 Activating paths .25
13.4.6 Deactivating paths .26
13.4.7 Re-creation of lost paths .27
13.4.8 Monitoring .27
13.5 Network management message format .27
13.5.1 General.27
13.5.2 Command and report reference .27
13.5.3 Message IDs for commands and reports .30
14 Diagnosis .31
14.1 General .31
14.2 Full-duplex network diagnosis .31
14.3 Half-duplex network diagnosis .31
14.4 Network diagnosis using diagnosis line .32
15 Timing definitions .33
15.1 Overview .33
15.2 Timer t .
Hello 34
15.2.1 Purpose .34
15.2.2 Start and stop conditions.34
15.2.3 Timer expiration .34
15.3 Timer t .
RD 34
15.3.1 Purpose .34
15.3.2 Start and stop conditions.34
15.3.3 Timer expiration .34
15.4 Timer t .
LNS_Termination 35
15.4.1 Purpose .35
15.4.2 Start and stop conditions.35
15.4.3 Timer expiration .35
16 Service interface definition to transport layer and network layer .35
Annex A (normative) Parameters for LNSI and network management messages .36
Annex B (informative) XSD for validation of XML .43
Annex C (informative) Network descriptor example .53
Bibliography .55
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ISO 21806-14:2021(E)

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
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
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.
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ISO 21806-14:2021(E)

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.
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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 in Figure 2. Stream transmission applications use a direct stream
data interface (transparent) to the data link layer.
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Figure 2 — The ISO 21806 series reference according to the OSI model
The International Organization for Standardization (ISO) draws attention to the fact that it is claimed
that compliance with this document may involve the use of a patent.
ISO takes no position concerning the evidence, validity and scope of this patent right.
The holder of this patent right has assured ISO that he/she is willing to negotiate licences under
reasonable and non-discriminatory terms and conditions with applicants throughout the world. In
this respect, the statement of the holder of this patent right is registered with ISO. Information may be
obtained from the patent database available at www .iso .org/ patents.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights other than those in the patent database. ISO shall not be held responsible for identifying
any or all such patent rights.
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INTERNATIONAL STANDARD ISO 21806-14:2021(E)
Road vehicles — Media Oriented Systems Transport
(MOST) —
Part 14:
Lean application layer
1 Scope
This document specifies the technical requirements for the lean application layer for MOST, a
synchronous time-division-multiplexing network.
The lean application layer includes a specification of the services available to control the configuration
and behaviour of the network management.
The lean application layer covers the definition of:
— node kinds,
— node addressing,
— data transport,
— network configuration,
— lean network services interface,
— network management, including connection management,
— diagnosis, and
— timing definitions.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 21806-1, Road vehicles — Media Oriented Systems Transport (MOST) — Part 1: General information
and definitions
ISO 21806-4, Road vehicles — Media Oriented Systems Transport (MOST) — Part 4: Transport layer and
network layer
ISO 21806-10, Road vehicles — Media Oriented Systems Transport (MOST) — Part 10: 150-Mbit/s coaxial
physical layer
ISO 21806-12, Road vehicles — Media Oriented Systems Transport (MOST) — Part 12: 50-Mbit/s balanced
media physical layer
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 21806-1 and the following apply.
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ISO and IEC maintain terminological databases for use in standardisation at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
3.1
coupling
tie between a streaming socket (3.11) and a network socket
3.2
lean network service
implementation of a software library that provides mechanisms to support node discovery (3.6) and
establish a network configuration (3.3)
3.3
network configuration
nodes currently connected to the network and paths (3.7) established for transmission
3.4
network descriptor
list of nodes allowed to participate in network communication, including valid paths (3.7) with
definition of couplings (3.1) and streaming connections
3.5
network supervisor
entity that is responsible for monitoring the network configuration (3.3)
3.6
node discovery
determination of the presence of the expected remote nodes (3.8)
3.7
path
two couplings (3.1) and a streaming connection
3.8
remote node
node that participates in a MOST network that conforms to this document and does not implement the
lean network services (3.2)
3.9
root node
node in a MOST network that controls the network (discover, configure, and connect)
3.10
signature
unique identification of a node
Note 1 to entry: The signature includes the logical node address, DiagID, MAC address, etc. It is provided at design
time. The signature is matched against the information contained in the network descriptor (3.4).
3.11
socket
interface of the MNC
Note 1 to entry: A socket is either a streaming socket or a network socket.
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3.12
source drop
detection of unavailability o
...