Intelligent transport systems (ITS) -- Data exchange involving roadside modules communication

ISO 15784-2:2015 specifies a mechanism to exchange data and messages in the following cases: a) between a traffic management centre(s) and roadside modules for traffic management; b) between roadside modules used for traffic management. The scope of this part of ISO 15784-2:2015 does not include the communication between traffic management centre and in-vehicle units, between roadside modules and in-vehicle units, in-vehicle communication, in-cabinet communication, or motion video transmission from a camera or recorded media. ISO 15784-2:2015 is complimentary to ISO 15784-3, but uses a different application layer for the information exchanges to configure, control, and monitor the field traffic control roadside modules. Where ISO 15784-3 is based on the DATEX standards, this part of ISO 15784 uses an alternative approach based on SNMP with an optional extension for more efficient transmission over low bandwidth media. Both of these standards conform to the application profile requirements set forth in ISO 15784-1.

Systèmes intelligents de transport (SIT) -- Échange de données impliquant la communication de modules en bordure de route

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Status
Published
Publication Date
02-Nov-2015
Current Stage
9060 - Close of review
Start Date
05-Mar-2021
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INTERNATIONAL ISO
STANDARD 15784-2
First edition
2015-11-01
Intelligent transport systems (ITS) —
Data exchange involving roadside
modules communication —
Part 2:
Centre to field device
communications using SNMP
Systèmes intelligents de transport (SIT) — Échange de données
impliquant la communication de modules en bordure de route —
Partie 2: Communications par dispositif du centre au terrain en
utilisant le protocole simple de gestion de réseau (SNMP)
Reference number
ISO 15784-2:2015(E)
ISO 2015
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ISO 15784-2:2015(E)
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ii © ISO 2015 – All rights reserved
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ISO 15784-2:2015(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

1.1 General ........................................................................................................................................................................................................... 1

1.2 Overview ...................................................................................................................................................................................................... 1

2 Conformance ............................................................................................................................................................................................................. 2

3 Normative references ...................................................................................................................................................................................... 2

4 Terms and definitions ..................................................................................................................................................................................... 3

5 Symbols and abbreviated terms ........................................................................................................................................................... 5

6 Overview ....................................................................................................................................................................................................................... 6

6.1 Conventions ............................................................................................................................................................................................... 6

6.1.1 ASN.1 .......................................................................................................................................................................................... 6

6.1.2 SNMP terminology ......................................................................................................................................................... 6

6.1.3 Format ....................................................................................................................................................................................... 6

6.2 ASN.1 modules and MIBs ............................................................................................................................................................... 6

6.3 Logical architecture ............................................................................................................................................................................ 7

6.4 Relationship to the OSI model ................................................................................................................................................... 7

7 Requirements .......................................................................................................................................................................................................... 8

7.1 Overview ...................................................................................................................................................................................................... 8

7.2 Terminology and architecture ................................................................................................................................................... 8

7.3 Message processing and dispatching ................................................................................................................................... 8

7.3.1 General...................................................................................................................................................................................... 8

7.3.2 Version 1 Message Processing Model ............................................................................................................ 9

7.3.3 Version 2 Message Processing Model ............................................................................................................ 9

7.3.4 Version 3 Message Processing Model ............................................................................................................ 9

7.3.5 STMP Message Processing Model ...................................................................................................................... 9

7.4 Applications ............................................................................................................................................................................................10

7.4.1 Entity type ..........................................................................................................................................................................10

7.4.2 Command generator ..................................................................................................................................................10

7.4.3 Command responder ........................................................................................................................................... ......10

7.4.4 Notification originator .............................................................................................................................................10

7.4.5 Notification receiver ..................................................................................................................................................10

7.4.6 Proxy forwarder ............................................................................................................................................................10

7.5 Security models ...................................................................................................................................................................................10

7.5.1 User-based Security Model for SNMP version 2 ................................................................................10

7.5.2 User-based Security Model for SNMP version 3 ................................................................................10

7.5.3 Transport Security Model .....................................................................................................................................11

7.6 View-based Access Control .......................................................................................................................................................11

7.7 Protocol operations..........................................................................................................................................................................11

7.7.1 SNMPv1 .................................................................................................................................................................................11

7.7.2 SNMPv2 .................................................................................................................................................................................12

7.7.3 SNMPv3 .................................................................................................................................................................................12

7.7.4 STMP........................................................................................................................................................................................12

7.7.5 Request ID variation ..................................................................................................................................................12

7.8 Transport mappings ........................................................................................................................................................................12

7.8.1 UDP over IPv4 .................................................................................................................................................................12

7.8.2 UDP over IPv6 .................................................................................................................................................................12

7.8.3 TCP over IPv4 ..................................................................................................................................................................13

7.8.4 TCP over IPv6 ..................................................................................................................................................................13

7.8.5 Secure Transport Model .........................................................................................................................................13

7.9 Management Information Base (MIB) .............................................................................................................................13

7.9.1 Agent MIBs .........................................................................................................................................................................13

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ISO 15784-2:2015(E)

7.9.2 Notification originator MIBs ...............................................................................................................................13

7.9.3 Proxy forwarder MIBs ..............................................................................................................................................14

7.9.4 STMP MIB ............................................................................................................................................................................14

7.9.5 Transport Security Model MIB ..........................................................................................................................14

7.9.6 Other supported data ........................................................................................................................................... .....14

7.10 Interoperability ...................................................................................................................................................................................14

8 Simple Transportation Management Protocol (STMP) .............................................................................................14

8.1 General ........................................................................................................................................................................................................14

8.2 Message dispatch, process, and protocol operations ..........................................................................................15

8.2.1 Dispatcher .................. .................................................... .....................................................................................................15

8.2.2 Message elements of procedure ......................................................................................................................15

8.2.3 STMP message field definitions .......................................................................................................................17

8.2.4 PDU elements of procedure .................................................................................................................................18

8.3 Transport mappings ........................................................................................................................................................................21

8.3.1 General...................................................................................................................................................................................21

8.3.2 UDP over IPv4 .................................................................................................................................................................21

8.3.3 UDP over IPv6 .................................................................................................................................................................22

8.3.4 TCP over IPv4 ..................................................................................................................................................................22

8.3.5 TCP over IPv6 ..................................................................................................................................................................23

9 Performance ...........................................................................................................................................................................................................23

9.1 Overview ...................................................................................................................................................................................................23

9.2 Default response time ....................................................................................................................................................................23

Annex A (normative) Profile requirements list .....................................................................................................................................25

Annex B (normative) STMP ASN.1 module ..................................................................................................................................................29

Annex C (normative) STMP management information base ....................................................................................................32

Annex D (informative) Primer for protocol ................................................................................................................................................37

Annex E (informative) Encoding examples .................................................................................................................................................45

Bibliography .............................................................................................................................................................................................................................48

iv © ISO 2015 – All rights reserved
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ISO 15784-2:2015(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 on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical

Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 204, Intelligent transport systems.

ISO 15784 consists of the following parts, under the general title Intelligent transport systems (ITS) —

Data exchange involving roadside modules communication:
— Part 1: General principles and documentation framework of application profiles
— Part 2: Centre to field device communications using SNMP
— Part 3: Application profile-data exchange (AP-DATEX)

This part of ISO 15784 deals with the use of SNMP based communications between traffic management

centres and roadside modules for the purpose of configuring, controlling, and monitoring their operation.

© ISO 2015 – All rights reserved v
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ISO 15784-2:2015(E)
Introduction
Background

The need for standardized communication with ITS field devices is growing around the world. A

number of countries have adopted SNMP-based field device communication standards.

There is a growing view and empirical evidence that standardizing this activity will result in improved

ITS performance, reduced cost, reduced deployment time, and improved maintainability. This part of

ISO 15784 creates a standard for ITS field device communications based on several simple concepts:

a) maximize the use of the SNMP standards which are widely used in the management of network

devices;

b) provide for the transport of data by means of serial communication, TCP/IP, UDP/IP, and other

transport mechanisms used by the Internet community;
c) provide security by the various mechanisms used in the Internet community;

d) provide data definitions using the MIB format defined by the SNMP community. The MIBs for ITS

device information will not be part of this part of ISO 15784 as these MIBs will be application, locale,

and jurisdiction specific to meet local needs. However, a basic set of management information

common to all implementations of this protocol is included.

By using this approach, agencies can specify open procurements and systems can be expanded

geographically in an open and non-proprietary manner which reduces the costs, speeds the deployment,

and simplifies the integration.
Overview

SNMP is a collection of well thought-out and well-proven concepts and principles. SNMP employs the

sound principles of abstraction and standardization. This has led to SNMP being widely accepted as the

prime choice for communication between management systems and devices on the Internet and other

communications networks.

The original implementation of SNMP was used to manage network devices such as routers and

switches. Since then, the use of SNMP has grown into many areas of application on the Internet and has

also been used successfully over various serial communications networks.

This part of ISO 15784 includes references to four variants of the network management protocol. Three

of these are versions of SNMP as defined by the Internet Engineering Task Force and the fourth is

defined in this part of ISO 15784 and is based on work in the U.S.

This part of ISO 15784 does not specify any requirements that contradict or cause non-conformance to

the base standards.
Document approach and layout
This part of ISO 15784 defines the following:

a) an overview of this part of ISO 15784, including conventions and architecture (Clause 6);

b) the major capabilities of this part of ISO 15784 (Clause 7);
c) the technical details of STMP (Clause 8);

d) performance requirements for entities claiming conformance to this part of ISO 15784 (Clause 9);

e) a protocol requirements list (Annex A);
f) the formal ASN.1 module for STMP (Annex B);
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ISO 15784-2:2015(E)

g) the formal definition of SNMP objects defined by this part of ISO 15784 (Annex C);

h) a primer for understanding the protocols defined in this part of ISO 15784 (Annex D);

i) example encodings of messages defined in this part of ISO 15784 (Annex E).
© ISO 2015 – All rights reserved vii
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INTERNATIONAL STANDARD ISO 15784-2:2015(E)
Intelligent transport systems (ITS) — Data exchange
involving roadside modules communication —
Part 2:
Centre to field device communications using SNMP
1 Scope
1.1 General

This part of ISO 15784 specifies a mechanism to exchange data and messages in the following cases:

a) between a traffic management centre(s) and roadside modules for traffic management;

b) between roadside modules used for traffic management.

The scope of this part of ISO 15784 does not include the communication between traffic management

centre and in-vehicle units, between roadside modules and in-vehicle units, in-vehicle communication,

in-cabinet communication, or motion video transmission from a camera or recorded media.

This part of ISO 15784 is complimentary to ISO 15784-3, but uses a different application layer for the

information exchanges to configure, control, and monitor the field traffic control roadside modules.

Where ISO 15784-3 is based on the DATEX standards, this part of ISO 15784 uses an alternative approach

based on SNMP with an optional extension for more efficient transmission over low bandwidth media.

Both of these standards conform to the application profile requirements set forth in ISO 15784-1.

1.2 Overview

This application profile is suitable for usage when the following conditions apply:

a) when the data to be exchanged can be defined as one or more elements that can be retrieved

or stored. The protocol can support a wide variety of devices and has adopted the concept of a

management information base (MIB) which identifies the configuration, control, and monitoring

parameters for the roadside module. This standardized approach is commonly used for network

management applications for devices such as routers, switches, bridges, and firewalls. It is also

used in many countries to control devices such as dynamic message signs;

b) when guaranteed, deterministic, real time exchange of data are not critical. SNMP operations are

typically fairly fast, but the underlying network can cause delays in delivering messages or even

lost messages; thus, the protocol is not appropriate for applications that require reliable sub-second

communications;

c) for intermittent exchange of any defined data. Normal SNMP operations allow messages to be

structured by combining any group of elements into a retrieval or storage request;

d) for repeated, frequent exchanges of the same message structure (with potentially different values)

on even low bandwidth links. This profile supports both an efficient variant of SNMP known as

STMP which allows the run-time definition of 13 messages that can be repeatedly exchanged as

needed with minimal overhead;

e) for allowing a roadside module to issue exception reports when special conditions arise. This profile

includes the concept of an inform message that allows an agent to notify the manager of special

conditions even though the manager did not specifically request the information at the time.

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ISO 15784-2:2015(E)

Note that this part of ISO 15784 does not address the data required for each specific type of ITS device.

Subsequent device communications standards are to be developed to identify the functionality of the

device and the objects to manage and monitor that functionality. This part of ISO 15784 is similar

to NTCIP 2301 that defines the protocols along with the objects required for controlling, operating,

monitoring, and diagnosing those protocols. Other standards define device-specific objects. It is

anticipated that regions will develop device MIB’s that meet their specific needs.

This part of ISO 15784 will allow for open systems deployment using devices from many manufacturers

providing a variety of services in a shared network environment. With such open protocols, public

MIB’s, and conformance to the standards, roadside modules can become interoperable among vendors

and a variety of vendors can provide product in a systems environment.
2 Conformance

Conformance to this part of ISO 15784 is defined in Annex A through the definition of each feature

as mandatory, optional, or conditional. Every effort has been made to make these conformance tables

consistent with the body of the text, but in the case of a conflict between the Annex and the main body

of this part of ISO 15784, Annex A shall take precedence.

This part of ISO 15784 explicitly identifies a number of options that an implementation may support.

These are options that are likely to be encountered in deployments and are listed in this part of

ISO 15784 as a convenience. The omission of a feature in this part of ISO 15784 should not be interpreted

as a prohibition of its use.
3 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 15784-1, Intelligent transport systems (ITS) — Data exchange involving roadside modules

communication — Part 1: General principles and documentation framework of application profiles

ISO/IEC 8825-7, Information technology — ASN.1 encoding rules — Part 7: Specification of Octet

Encoding Rules (OER)
IETF RFC 1157, A Simple Network Management Protocol (SNMP)

IETF RFC 1905, Protocol Operations for Version 2 of the Simple Network Management Protocol (SNMPv2)

IETF RFC 1910, User Based Security Model for SNMPv2
IETF RFC 2578, Structure of Management Information Version 2 (SMIv2)
IETF RFC 3411:2002, An Architecture for Describing SNMP Management Frameworks
IETF RFC 3412:2002, Message Processing and Dispatching
IETF RFC 3413:2002, SNMP Applications
IETF RFC 3414:2002, User-based Security Model
IETF RFC 3415:2002, View-based Access Control Model
IETF RFC 3416, Version 2 of SNMP Protocol Operations
IETF RFC 3417:2002, Transport Mappings

IETF RFC 3418:2002, Management Information Base (MIB) for the Simple Network Management

Protocol (SNMP)
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ISO 15784-2:2015(E)

IETF RFC 3584, Coexistence between Version 1, Version 2, and Version 3 of the Internet-standard Network

Management Framework

IETF RFC 3826:2004, The Advanced Encryption Standard (AES) Cipher Algorithm in the SNMP User-based

Security Model

IETF RFC 5590:2009, Transport Subsystem for the Simple Network Management Protocol (SNMP)

IETF RFC 5591:2009, Transport Security Model for the Simple Network Management Protocol (SNMP)

IETF RFC 6353, Transport Layer Security (TLS) Transport Model for the Simple Network Management

Protocol (SNMP)
4 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
4.1
agent
SNMP entity (4.20) that can respond to SNMP get and set requests

Note 1 to entry: An agent can also issue report, trap, and/or inform messages (4.10).

4.2
component
any equipment connected to the ITS infrastructure

Note 1 to entry: Components can be either management centre components or field components. Components in

an ITS system can be supplied by more than one manufacturer.
4.3
datagram
self-contained unit of data transmitted independently of other units of data
4.4
deprecated
still valid, but is not to
...

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