EN ISO 17423:2025
(Main)Intelligent transport systems - Application requirements and objectives (ISO 17423:2025)
Intelligent transport systems - Application requirements and objectives (ISO 17423:2025)
This document:
— specifies communication service parameters presented by ITS station (ITS-S) application processes to the ITS-S management in support of automatic selection of ITS-S communication profiles in an ITS station unit (ITS-SU);
— specifies related procedures for the static and dynamic ITS-S communication profile selection processes at a high functional level;
— provides an illustration of objectives used to estimate an optimum ITS-S communication profile.
Intelligente Verkehrssysteme - Anwendungsanforderungen und Grundsätze (ISO 17423:2025)
Systèmes de transport intelligents - Exigences et objectifs des applications (ISO 17423:2025)
Le présent document:
— spécifie les paramètres de service de communication présentés par les processus d'application de la station ITS (processus d’application ITS-S) à l’entité de gestion ITS-S afin de faciliter la sélection automatique des profils de communication ITS-S au sein d'une unité de station ITS (ITS-SU);
— spécifie les procédures liées aux processus de sélection des profils de communication ITS-S statiques et dynamiques à un niveau fonctionnel élevé;
— fournit une illustration des objectifs permettant d'estimer un profil de communication ITS-S optimal.
Inteligentni transportni sistemi - Zahteve in cilji (ISO 17423:2025)
Ta dokument: – določa parametre komunikacijske storitve, ki jih aplikacijski postopki postaje ITS (ITS-S) predstavljajo upravljanju ITS-S v podporo samodejni izbiri komunikacijskih profilov ITS-S na enoti postaje ITS (ITS-SU), – določa povezane postopke za statične in dinamične postopke izbire komunikacijskih profilov ITS-S na visoki funkcionalni ravni; – zagotavlja pregled ciljev, uporabljenih za predvidevanje optimalnega komunikacijskega profila ITS-S.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2025
Nadomešča:
SIST EN ISO 17423:2018
Inteligentni transportni sistemi - Zahteve in cilji (ISO 17423:2025)
Intelligent transport systems - Application requirements and objectives (ISO 17423:2025)
Intelligente Verkehrssysteme - Anwendungsanforderungen und Grundsätze (ISO
17423:2025)
Systèmes de transport intelligents - Exigences et objectifs des applications (ISO
17423:2025)
Ta slovenski standard je istoveten z: EN ISO 17423:2025
ICS:
03.220.01 Transport na splošno Transport in general
35.240.60 Uporabniške rešitve IT v IT applications in transport
prometu
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 17423
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2025
EUROPÄISCHE NORM
ICS 03.220.20 Supersedes EN ISO 17423:2018
English Version
Intelligent transport systems - Application requirements
and objectives (ISO 17423:2025)
Systèmes de transport intelligents - Exigences et Intelligente Verkehrssysteme -
objectifs des applications (ISO 17423:2025) Anwendungsanforderungen und Grundsätze (ISO
17423:2025)
This European Standard was approved by CEN on 19 December 2024.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
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Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
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CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 17423:2025 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 17423:2025) has been prepared by Technical Committee ISO/TC 204
"Intelligent transport systems" in collaboration with Technical Committee CEN/TC 278 “Intelligent
transport systems” the secretariat of which is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by October 2025, and conflicting national standards shall
be withdrawn at the latest by October 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 17423:2018.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 17423:2025 has been approved by CEN as EN ISO 17423:2025 without any modification.
International
Standard
ISO 17423
Second edition
Intelligent transport systems —
2025-04
Application requirements and
objectives
Systèmes de transport intelligents — Exigences et objectifs des
applications
Reference number
ISO 17423:2025(en) © ISO 2025
ISO 17423:2025(en)
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ii
ISO 17423:2025(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Communication service parameters . 3
5.1 Abstraction of application processes from communications.3
5.2 Communication service parameter classes .7
5.3 Operational CSPs .7
5.3.1 List of CSPs .7
5.3.2 Logical channel .7
5.3.3 Session continuity .8
5.3.4 Average ADU generation rate .8
5.3.5 Flow type.8
5.3.6 Maximum priority .8
5.3.7 Port number .8
5.3.8 Expected flow lifetime .9
5.4 Destination CSPs .9
5.4.1 List of CSPs .9
5.4.2 Destination type .9
5.4.3 Destination domain .9
5.4.4 Communication distance .10
5.4.5 Directivity .10
5.5 Performance CSPs .10
5.5.1 List of CSPs .10
5.5.2 Resilience .10
5.5.3 Minimum required throughput .10
5.5.4 Maximum allowed latency .11
5.5.5 Maximum ADU size .11
5.6 Security CSPs .11
5.6.1 List of CSPs .11
5.6.2 Need for data confidentiality .11
5.6.3 Need for data integrity. 12
5.6.4 Need for non-repudiation . 12
5.6.5 Need for source ITS-S application process authentication . 12
5.7 Protocol CSP . 12
5.7.1 List of CSPs . 12
5.7.2 Communication protocol stack . 12
5.7.3 Specific communications protocols . 12
5.8 CSPs for sinks . 13
5.9 CSPs overview . 13
6 Policies and regulations . 14
6.1 Cost policy.14
6.1.1 List of rules .14
6.1.2 Flat rate. 15
6.1.3 Maximum rate per data unit . 15
6.1.4 Maximum rate per connection time . 15
6.1.5 Maximum rate per connection .16
6.2 Need for station anonymity .16
6.3 Need for station location privacy .16
6.4 Support of station authentication .16
iii
ISO 17423:2025(en)
7 ITS-S procedures for ITS-S communication profile selection .16
7.1 Overview .16
7.2 Presentation of CSPs .17
7.3 Monitoring of capabilities of communications .18
7.4 Monitoring of regulations and policies .18
7.5 Selection of ITS-S communication profiles .18
7.6 Interaction with user of ITS-SU .19
7.7 Support of other application processes .19
Annex A (normative) ASN.1 modules .20
Annex B (informative) Example of presentation of CSPs .27
Annex C (informative) Communication requirements and objectives .30
Bibliography .33
iv
ISO 17423:2025(en)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 204, Intelligent transport systems, in
collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC 278,
Intelligent transport systems, in accordance with the Agreement on technical cooperation between ISO and
CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 17423:2018), which has been technically
revised.
The main changes are as follows:
— "Cooperative systems" has been removed from the title to align with the unchanged Scope;
— references have been updated;
— the ASN.1 module has been aligned with the latest developments of other ASN.1 modules (this alignment
does not introduce technical changes in the module);
— general editorial improvements have been performed to improve readability.
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.
v
ISO 17423:2025(en)
Introduction
Abstracting applications from communications is a useful basic architectural principle of intelligent
transport systems (ITS) embodied in the ITS station and communication architecture presented in
ISO 21217.
NOTE The term “Cooperative ITS” (C-ITS) indicates specific features of ITS. For the purposes of this document, no
distinction between ITS and C-ITS is needed.
Applications and communications are linked together using the concepts of flows and paths and
communication profiles described in ISO 21217, with related flow and path management procedures specified
in ISO 24102-6. ITS station management uses communication requirements and objectives of applications,
together with the capabilities of the ITS station (status of available communication protocol stacks) and sets
of decision rules (regulations and policies), to select suitable parameterized ITS-S communication protocol
stacks, also referred to as "ITS-S Communication profiles" (ITS-SCP), for each source of a potential flow, as
illustrated in Figure 1. A set of communication requirements is referred to as a "flow type" in ISO 24102-6.
Well-known registered flow types are specified in ISO 17419.
Figure 1 — ITS-S communication profile selection process
An ITS-S communication profile is independent of any destination address. However, an instantiation
of a communication profile includes the address of the next hop recipient, and a path includes address
information of the next hop recipient, the anchor and the destination, as specified in ISO 24102-6.
A user of an ITS station unit can influence the selection of ITS-S communication profiles by providing their
own policies.
Information from a local dynamic map (LDM; see ISO 18750) on neighbouring stations offering certain
communication capabilities can also be useful for the ITS-S communication profile selection process,
although not indispensable.
vi
International Standard ISO 17423:2025(en)
Intelligent transport systems — Application requirements
and objectives
1 Scope
This document:
— specifies communication service parameters presented by ITS station (ITS-S) application processes
to the ITS-S management in support of automatic selection of ITS-S communication profiles in an ITS
station unit (ITS-SU);
— specifies related procedures for the static and dynamic ITS-S communication profile selection processes
at a high functional level;
— provides an illustration of objectives used to estimate an optimum ITS-S communication profile.
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 4217, Codes for the representation of currencies
ISO 17419, Intelligent transport systems — Globally unique identification
ISO 21217, Intelligent transport systems — Station and communication architecture
ITU-T X.911, Information technology — Open distributed processing — Reference model — Enterprise language
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 17419, ISO 21217, ITU-T X.911 and
the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
ITS-S application process RX/TX interface
sink or source of an ITS-S application process
ISO 17423:2025(en)
4 Abbreviated terms
ADU application data unit
APDU application protocol data unit
BSME bounded secured managed entity (see ISO 21217)
CAM cooperative awareness message
CPSP communication profile selection process
CRO communication requirements and objectives
CSP communication service parameter
CSP_AvgADUrate communication service parameter “Average ADU generation rate”
CSP_CommDistance communication service parameter “Communication distance”
CSP_DataConfidentiality communication service parameter “Need for data confidentiality”
CSP_DataIntegrity communication service parameter “Need for data integrity”
CSP_DestinationDomain communication service parameter “Destination domain”
CSP_DestinationType communication service parameter “Destination type”
CSP_Directivity communication service parameter “Directivity”
CSP_ExpFlowLifetime communication service parameter “Expected flow lifetime”
CSP_FlowType communication service parameter “Flow type”
CSP_LogicalChannelType communication service parameter “Logical channel”
CSP_MaxADU communication service parameter “Maximum ADU size”
CSP_MaxLat communication service parameter “Maximum allowed latency”
CSP_MaxPrio communication service parameter “Maximum priority”
CSP_MinThP communication service parameter “Minimum throughput”
CSP_NonRepudiation communication service parameter “Need for non-repudiation”
CSP_PortNo communication service parameter “Port number”
CSP_Protocol communication service parameter “Protocol requirements”
CSP_Resilience communication service parameter “Resilience”
CSP_SessionCont communication service parameter “Session continuity”
CSP_SourceAuthentication communication service parameter “Source authentication”
CSP_SpecificCommsProts communication service parameter “Specific communications protocols”
DENM decentralized environmental notification message
FNTP fast networking and transport protocol
ISO 17423:2025(en)
FSAP fast service advertisement protocol
ITS-S-FlowID flow identifier (see ISO 24102-6)
IICP ITS station-internal management communications protocol (see ISO 24102-4)
ITS-S ITS station (see ISO 21217)
ITS-SCP ITS station communication profile
ITS-SCPS ITS station communication protocol stack
ITS-SCU ITS station communication unit (see ISO 21217)
ITS-SU ITS station unit (see ISO 21217)
MA-SAP service access point between ITS-S management entity and ITS-S application
entity
MF-SAP service access point between ITS-S management entity and ITS-S facilities layer
MS-SAP service access point between ITS-S management entity and ITS-S security entity
R_ConnectRate “maximum rate per connection” rule
R_ConnectTimeRate “maximum rate per connection time” rule
R_DataUnitRate “maximum rate per data unit” rule
R_FlatRate “flat rate” rule
R_StationAnonymity “need for station anonymity” rule
R_StationAuthentication “support of station authentication” rule
R_StationLocationPrivacy “need for station location privacy” rule
ITS-S-FlowTypeID ITS-S flow type identifier (see ISO 24102-6)
SAM service advertisement message
SPaT signal phase and timing
SRM service response message
5 Communication service parameters
5.1 Abstraction of application processes from communications
The ITS station (ITS-S) reference architecture presented in Figure 2 and specified in ISO 21217 distinguishes
two main blocks, i.e. "applications" and "communications". ITS-S application processes in "applications"
access communication services in "communications" through an API. Portability of ITS-S application
processes, which leads to the creation of ITS application process repositories as described in ISO 17419, is
enabled by:
— abstraction of ITS-S application processes (e.g. in "applications") from communication protocols (in
"Facilities", "Networking & Transport", "Access") and supporting management and security functionality
(in "Management", "Security") introduced as essential basics of an ITS station in ISO 21217;
ISO 17423:2025(en)
— procedures by which instances of ITS-S application processes running in an ITS station unit (ITS-
SU) specified in ISO 21217 can present requirements for communication services in an abstract and
standardized way to the ITS station management as specified in this document;
— procedures for automatic selection of optimum communication profiles by the ITS station management
for each set of required communication services.
Communication service requirements are presented by means of "communication service parameters"
(CSP) as identified in this document. These parameters are used to identify sets of possible choices of ITS-S
communication profiles as well as selecting the "optimal" ITS-S communication profile out of each set. The
selection of the "optimal" ITS-S communication profile is implementation-dependent and generally involves
the formulation of a cost function based on objectives. The cost function is extremized (maximized or
minimized) as discussed in Annex C.
Figure 2 — ITS station architecture (ISO 21217)
The same approach to present communication requirements and objectives also applies to:
— ITS-S application processes located in the ITS-S facilities layer (e.g. CAM source, specified in ETSI EN 302
[15]
637-2 );
— ITS-S application processes located in the ITS-S management entity (e.g. SAM and SRM sources specified
in ISO 16460 and ISO 22418);
— ITS-S application processes located in the ITS-S security entity;
— ITS-S application processes located somewhere else in an ITS station.
ISO 17423:2025(en)
NOTE In an implementation, there can also be other application processes accessing communication services of
an ITS-SU without meeting necessary security requirements. Such other application processes are not certified to
be installed in an ITS-SU implemented as a BSME as described in ISO 21217 and ISO 17419, but can use a selected
functionality from it, especially a communication functionality.
Figure 3 illustrates a simplified version of Figure 2 to be applied to the process illustrated in Figure 1
considering ITS-S application processes in general. The functionality of block “facilities” in Figure 2 is within
the block “ITS-S application processes” in Figure 3.
Figure 3 — Simplified architecture
Application processes are classified in ISO 17419 as:
— ITS-S application processes certified for a BSME and identified by an ITS-AID (ITS-S facilities applications,
ITS-S management applications, ITS-S security applications and ITS-S applications):
— authorized ITS-S applications;
— permitted ITS-S applications;
— application processes not certified for a BSME and without ITS-AID.
[14]
The definitions of "authorized" and "permitted" are given in ITU-T X.911.
CSPs for ITS-S application process sources are specified in 5.3, 5.4, 5.5, 5.6 and 5.7. An overview is presented
in 5.9. An ITS-S application process shall present the mandatory CSPs, and may present those optional CSPs
which are relevant for it. Mandatory CSPs shall be treated as optional in case CSP_FlowType is presented.
Users of ITS-SUs may present rules, see Figure 1, by means of user policies, e.g. for cases where the ITS-S
application process did not specify a specific value (e.g. financial requirements). Requirements may also be
given by authorities in terms of regulations and policies, or by other entities in terms of policies; see Figure 1.
NOTE 1 Regulations are enforceable rules. Policies are rules or guidelines which cannot be enforced.
An ITS-S application process may have more than one communication source (/ sink) (ITS-S application
process RX/TX interface), and these communication sources may have different communication
requirements.
NOTE 2 It can be necessary for an ITS-S application process to maintain flows for different communication sources,
e.g. audio, video and messages.
Each communication source (and sink) of an ITS-S application process is identified by a reference
number of ASN.1 type ITSappProcSinkSourceNo specified in ISO 17419 which is unique in the scope of
ISO 17423:2025(en)
that ITS-S application process. For each communication source, an ITS-S application process presents a
set of communication requirements to the ITS-S management as specified in this document. Such a set of
communication requirements is linked to an ITS flow type identifier (ITS-S-FlowTypeID). ITS-S-FlowTypeIDs
may be well-known registered identifiers pointing to pre-defined well-known sets of requirements or may
be dynamically assigned in an ITS-SU.
Information contained in a registry for ITS flow types is given by the ASN.1 type ITSflowTypeRegistry
specified in Annex A. This registry shall contain entries for ITS flow types given by the ASN.1 type
ITSflowType as specified in Annex A and listed in Table 1. A registration authority may add further
information elements to properly identify and support management of ITS flow types. A registration
authority shall clearly distinguish the range of well-known registered ITS-FlowTypeIDs and dynamically
assigned ITS-FlowTypeIDs.
NOTE 3 A general introduction on registries for unique identifiers in ITS is provided in ISO 17419.
Table 1 — Registry components of ITSflowType
Component ofITS- Semantics
flowType
id FlowTypeID
req
List of applicable communication service parameters ITSSappCPReqReg. The communication
service parameter CSP_FlowType presenting a value of ITS-FlowTypeID is prohibited in req.
The CostObjective used in some communication service parameters is not part of a regis-
tered ITS flow type. Thus, the value presented in the registry is not relevant. The convention
shall be to use the value 255 (maximum relevance) in the registry, and to replace it by an
applicable value upon usage.
CSPs presented by ITS-S application processes for each communication source are used by the ITS station
management to select the best suited ITS-S communication profile per communication source. It can be
that an ITS-S management is not able to provide a communication protocol stack which fully complies
with the requirements, i.e. fails to identify and select an appropriate ITS-S communication profile. In
this failure situation either a best effort approach to enable communications or a refusal to support this
particular communication source applies. In any case, the ITS-S management reports the status of the ITS-S
communication profile selection procedure to the ITS-S application process.
Once an ITS-S-FlowID has been assigned to an ITS-S application process (see ISO 24102-6), the ITS-S
application process can complete the following actions, for example, using the procedures specified in
ISO/TS 17429:2017, Clause 8:
— present ADUs for transmission;
— publish data objects;
— subscribe to reception of data objects.
[11]
Once an ITS-S-FlowID has been assigned to an ITS-S application process (see ISO 24102-6 ) the ITS-S
application process cannot update CSPs associated with the flow.
An ITS-S application process may also present requirements on communication sinks (ITS-S application
process RX/TX interface), e.g. to request opening a receive port identified by an ITS port number (ITS-PN).
Similarly to the communication sources of an ITS-S application process, these communication sinks are
uniquely identified by a reference number of ASN.1 type ITSappProcSinkSourceNo, specified in ISO 17419.
CSPs for ITS-S application process sinks are specified in 5.8.
The interface between "Applications" and "Communications" illustrated in Figure 1 is an "application
programming interface" (API). An API provides the functionality described in the service access points MA-
SAP, SA-SAP and FA-SAP, specified in ISO 24102-3. Details of APIs depend on the operating system used to
implement them.
ITS-S application processes may reside in the ITS-S application entity, the ITS-S facilities layer, in the ITS-S
security entity, and in the ITS-S management entity. The interaction between ITS-S application processes
ISO 17423:2025(en)
and the ITS-S management entity is specified in terms of functions in the service primitives of the MA-SAP,
the MF-SAP, and the MS-SAP illustrated in Figure 2.
The specification of APIs for ITS is outside the scope of this document.
Management procedures and service primitives related to these CSPs are specified in Clause 7.
Annex A provides an ASN.1 module with specifications of types and values used to present the communication
requirements and objectives.
5.2 Communication service parameter classes
CSPs are grouped into classes. The following communication service parameter classes are identified in this
document.
— The class of operational CSPs is specified in 5.3.
— The class of destination CSPs is specified in 5.4.
— The class of performance CSPs is specified in 5.5.
— The class of security CSPs is specified in 5.6.
— The class of protocol CSPs is specified in 5.7.
— CSPs relevant for ITS-S application process sinks are specified in 5.8
— An overview of all CSPs identified in this document is presented in 5.9.
Some CSPs are mandatory, i.e. shall be presented by all ITS-S application processes as specified in 7.2.
ASN.1 specifications of the CSPs are provided in Annex A.
5.3 Operational CSPs
5.3.1 List of CSPs
Operational CSPs specified in this document are:
— "Logical channel" communication service parameter CSP_LogicalChannelType (mandatory) as specified
in 5.3.2;
— "Session continuity" communication service parameter CSP_SessionCont (optional) as specified in 5.3.3;
— "Average ADU generation rate" communication service parameter CSP_AvgADUrate (optional) as
specified in 5.3.4;
— "FlowType" communication service parameter CSP_FlowType (optional) as specified in 5.3.5;
— "Maximum priority" communication service parameter CSP_MaxPrio (optional) as specified in 5.3.6;
— "Port number" communication service parameter CSP_PortNo (mandatory) as specified in 5.3.7;
— "Expected flow lifetime" communication service parameter CSP_ExpFlowLifetime (optional) as specified
in 5.3.8.
5.3.2 Logical channel
CSP_LogicalChannelType indicates the logical channel to be used for communications. It shall
always be presented by an ITS-S application process. CSP_LogicalChannelType shall be of ASN.1 type
LogicalChannelType specified in ISO 17419.
ISO 17423:2025(en)
Logical channels are subject to registration as specified in ISO 17419. Some examples of logical channels are
presented in Table 2.
Table 2 — Examples of logical channels
Acronym Name Description
CCH Control channel For dissemination and exchange of basic channel control informa-
tion, communication information, and application management
information.
SaCH Service advertisement channel For advertising of applications and services e.g. using FSAP speci-
fied in ISO 22418.
SfCH Safety of life and property chan- For dissemination and exchange of safety of life and property criti-
nel cal information.
SCH Service channel For exchange of peer to peer ITS-S application process data, and for
general message dissemination.
5.3.3 Session continuity
CSP_SessionCont indicates that the flow is related to a session. CSP_SessionCont shall be of ASN.1 type
SessionCont, specified in Annex A.
SessionCont is a binary flag indicating whether a session may be interrupted or not. If the binary flag is set
to one, an active session should not be interrupted by the station management.
5.3.4 Average ADU generation rate
CSP_AvgADUrate indicates the repetition period (time) at which ADUs will be presented for transmission.
It is applicable only for information dissemination. CSP_AvgADUrate shall be of ASN.1 type AvgADUrate
specified in Annex A.
The value zero indicates an unknown average rate.
If CSP_AvgADUrate is not presented, then the value of zero shall apply.
5.3.5 Flow type
CSP_FlowType presents a well-known registered flow type identifier FlowTypeID specified in ISO 17419,
which uniquely points to a set of pre-defined CSPs. CSP_FlowType shall be of ASN.1 type FlowTypeID,
specified in Annex A.
When CSP_FlowType is presented, no other CSPs need to be presented, including those indicated to be
mandatory. CSP_FlowType shall overrule other CSPs that conflict with the implicit CSPs identified by CSP_
FlowType.
5.3.6 Maximum priority
CSP_MaxPrio presents the maximum allowed priority for flows. If CSP_MaxPrio is not present, lowest
priority zero is assumed. CSP_MaxPrio shall be of ASN.1 type ITSapObPriority, specified in Annex A.
5.3.7 Port number
CSP_PortNo is a mandatory CSP that consists of two parts: a direction indicator of ASN.1 type PortRxTx and
the port number mappings of ASN.1 type PortNumberMappings. CSP_PortNo is presented for communication
sources and communication sinks to indicate a well-known port number to be associated with the interface.
CSP_PortNo shall be of ASN.1 type PortNoInfo, specified in Annex A.
NOTE A ”well-known port number” is a port number related to a specific transport protocol for a specific purpose.
Such well-known port numbers are published in a registry related to the respective transport protocol.
ISO 17423:2025(en)
If the given interface is not associated with a well-known port, the port number PORT_UNK specified in
ISO 17419 shall be presented where the transport protocol specified in ISO/TS 16460 is used.
5.3.8 Expected flow lifetime
CSP_ExpFlowLifetime indicates the expected lifetime of a flow. CSP_ExpFlowLifetime shall be of ASN.1 type
ExpFlowLifeTime, specified in Annex A.
ExpFlowLifeTime consists of time information of ASN.1 type TimeDurationValue. TimeDurationValue
indicates the expected time for a flow. A time value of zero indicates "time unknown".
In case CSP_ExpFlowLifetime is not presented, then the value of zero shall apply.
5.4 Destination CSPs
5.4.1 List of CSPs
Destination CSPs specified in this document are:
— "Destination type" communication service parameter CSP_DestinationType (mandatory) as specified
in 5.4.2.
— "Destination domain" communication service parameter CSP_DestinationDomain (mandatory)
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