IEC 61158-3-1:2007

IEC 61158-3-1
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 3-1: Data-link layer service definition – Type 1 elements

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IEC 61158-3-1
Edition 1.0 2007-12
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 3-1: Data-link layer service definition – Type 1 elements

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XF
ICS 35.100.20; 25.040.40 ISBN 2-8318-9410-7

– 2 – 61158-3-1 © IEC:2007(E)
CONTENTS
FOREWORD.7
0 Introduction .9
0.1 General .9
0.2 Nomenclature for references within this standard .9
1 Scope.10
1.1 Overview .10
1.2 Specifications .10
1.3 Conformance.10
2 Normative references.11
3 Terms, definitions, symbols, abbreviations and conventions .11
3.1 Reference model terms and definitions .11
3.2 Service convention terms and definitions .13
3.3 Data-link service terms and definitions.13
3.4 Common symbols and abbreviations .17
3.5 Common conventions .17
4 Overview of the data-link layer service .19
4.1 General .19
4.2 Types and classes of data-link layer service.21
4.3 Quality-of-service (QoS) attributes common to multiple types of data-link layer
service .22
5 DL(SAP)-address, queue and buffer management data-link layer service .27
5.1 Facilities of the DL(SAP)-address, queue and buffer management data-link
layer service .27
5.2 Model of the DL(SAP)-address, queue and buffer management data-link layer
service .27
5.3 Sequence of primitives at one DLSAP .27
5.4 DL(SAP)-address, queue and buffer management facilities .29
6 Connection-mode data-link layer service .43
6.1 Facilities of the connection-mode data-link layer service .43
6.2 Model of the connection-mode data-link layer service.44
6.3 Quality of connection-mode service.50
6.4 Sequence of primitives .56
6.5 Connection establishment phase.66
6.6 Connection release phase.73
6.7 Data transfer phase .79
7 Connectionless-mode data-link layer service.90
7.1 Facilities of the connectionless-mode data-link layer service .90
7.2 Model of the connectionless-mode data-link layer service.91
7.3 Quality of connectionless-mode service .92
7.4 Sequence of primitives .93
7.5 Connectionless-mode functions .95
8 Time and scheduling guidance data-link layer service . 106
8.1 Facilities and classes of the time and scheduling guidance data-link layer
service . 106
8.2 Model of the time and scheduling guidance data-link layer service. 107
8.3 Quality of scheduling guidance service. 107
8.4 Sequence of primitives at one DLE . 107

61158-3-1 © IEC:2007(E) – 3 –
8.5 Scheduling guidance functions. 108
9 DL-management service . 119
9.1 Scope and inheritance . 119
9.2 Facilities of the DL-management service. 119
9.3 Model of the DL-management service . 119
9.4 Constraints on sequence of primitives. 119
9.5 Set .120
9.6 Get.121
9.7 Action.121
9.8 Event. 122
Bibliography . 124

Figure 1 – Relationships of DLSAPs, DLSAP-addresses, DLCEPs, DLCEP-addresses,
DLSEP-addresses and group DL-addresses .14
Figure 2 – Example of paths, links, bridges, and the extended link.20
Figure 3 – Types of DL-timeliness In terms of elapsed DL-time and events at the
assessing DLCEP.25
Figure 4 – Sequence of primitives for the DL(SAP)-address, queue and buffer
management DLS.29
Figure 5 – Supported methods of data management for transmission and delivery .30
Figure 6 – Peer-to-peer and multi-peer DLCs and their DLCEPs .43
Figure 7 – OSI abstract queue model of a peer DLC between a pair of DLS-users .45
Figure 8 – OSI abstract queue model of a multi-peer DLC between a publishing DLS-
user and a set of subscribing DLS-users.48
Figure 9 – Summary of DL-connection-mode service primitive time-sequence diagrams
for peer DLCs (portion 1) .59
Figure 10 – Summary of DL-connection-mode service primitive time-sequence diagrams
for peer DLCs (portion 2) .60
Figure 11 – Summary of DL-connection-mode service primitive time-sequence diagrams
for publishers of a multi-peer DLC (portion 1).61
Figure 12 – Summary of DL-connection-mode service primitive time-sequence diagrams
for publishers of a multi-peer DLC (portion 2).62
Figure 13 – Summary of additional DL-connection-mode service primitive time-
sequence diagrams for a multi-peer DLC subscriber where the diagrams differ
from the corresponding ones for a publisher (portion 1).
Figure 14 – Summary of additional DL-connection-mode service primitive time-
sequence diagrams for a multi-peer DLC subscriber where the diagrams differ
from the corresponding ones for a publisher (portion 2).64
Figure 15 – State transition diagram for sequences of DL-connection-mode service
primitives at a DLCEP.65
Figure 16 – Peer DLC/DLCEP establishment initiated by a single DLS-user .71
Figure 17 – Multi-peer DLC/DLCEP establishment initiated by the publishing DLS-user.71
Figure 18 – Multi-peer DLC/DLCEP establishment initiated by a subscribing DLS-user.72
Figure 19 – Multi-peer DLC/DLCEP establishment using known DLCEP addresses
initiated first by the publishing DLS-user .72
Figure 20 – Multi-peer DLC/DLCEP establishment using known DLCEP addresses
initiated first by one or more subscribing DLS-users.72
Figure 21 – Peer DLC/DLCEP establishment initiated simultaneously by both peer DLS-
users, resulting in a merged DLC.72

– 4 – 61158-3-1 © IEC:2007(E)
Figure 22 – Multi-peer DLC/DLCEP establishment initiated simultaneously by both
publishing and subscribing DLS-users, resulting in a merged DLC .73
Figure 23 – Peer DLS-user invocation .75
Figure 24 – Publishing DLS-user invocation.75
Figure 25 – Subscribing DLS-user invocation.76
Figure 26 – Simultaneous invocation by both DLS-users .76
Figure 27 – Peer DLS-provider invocation.76
Figure 28 – Publishing DLS-provider invocation .76
Figure 29 – Subscribing DLS-provider invocation.76
Figure 30 – Simultaneous peer DLS-user and DLS-provider invocations .76
Figure 31 – Simultaneous publishing DLS-user and DLS-provider invocations.76
Figure 32 – Simultaneous subscribing DLS-user and DLS-provider invocations.76
Figure 33 – Sequence of primitives in a peer DLS-user rejection of a DLC/DLCEP
establishment attempt .77
Figure 34 – Sequence of primitives in a publishing DLS-user rejection of a DLC/DLCEP
establishment attempt .77
Figure 35 – Sequence of primitives in a subscribing DLS-user rejection of a DLC/DLCEP
establishment attempt .77
Figure 36 – Sequence of primitives in a DLS-provider rejection of a DLC/DLCEP
establishment attempt .77
Figure 37 – Sequence of primitives in a DLS-user cancellation of a DLC/DLCEP
establishment attempt: both primitives are destroyed in the queue .78
Figure 38 – Sequence of primitives in a DLS-user cancellation of a DLC/DLCEP
establishment attempt: DL-DISCONNECT indication arrives before DL-CONNECT
response is sent .78
Figure 39 – Sequence of primitives in a DLS-user cancellation of a DLC/DLCEP
establishment attempt: peer DL-DISCONNECT indication arrives after
DL-CONNECT response is sent.78
Figure 40 – Sequence of primitives in a DLS-user cancellation of a DLC/DLCEP
establishment attempt: publisher’s DL-DISCONNECT indication arrives after
DL-CONNECT response is sent.78
Figure 41 – Sequence of primitives in a DLS-user cancellation of a DLC/DLCEP
establishment attempt: subscriber’s DL-DISCONNECT request arrives after
DL-CONNECT request has been communicated to the publisher .79
Figure 42 – Sequence of primitives for a CLASSICAL or DISORDERED peer-to-peer queue-
to-queue data transfer .81
Figure 43 – Sequence of primitives for an ORDERED or UNORDERED peer-to-peer, or an
UNORDERED subscriber-to-publisher queue-to-queue data transfer .81
Figure 44 – Sequence of primitives for a publisher-to-subscribers queue-to-queue data
transfer .81
Figure 45 – Sequence of primitives for a failed queue-to-queue data transfer.82
Figure 46 – Sequence of primitives for an ORDERED or UNORDERED peer to peer, or an
UNORDERED subscriber to publisher, buffer to buffer data transfer .83
Figure 47 – Sequence of primitives for a publisher to subscribers buffer to buffer data
transfer .83
Figure 48 – Sequence of primitives for an ORDERED or UNORDERED peer to peer, or an
UNORDERED subscriber to publisher, buffer to queue data transfer.83
Figure 49 – Sequence of primitives for a publisher to subscribers buffer to queue data
transfer .83
Figure 50 – Sequence of primitives in a peer DLS-user initiated Reset.87

61158-3-1 © IEC:2007(E) – 5 –
Figure 51 – Sequence of primitives in a publishing DLS-user initiated Reset .87
Figure 52 – Sequence of primitives in a subscribing DLS-user initiated Reset .87
Figure 53 – Sequence of primitives in a simultaneous peer DLS-users initiated Reset.87
Figure 54 – Sequence of primitives in a simultaneous multi-peer DLS-users initiated
Reset .87
Figure 55 – Sequence of primitives in a peer DLS-provider initiated Reset .88
Figure 56 – Sequence of primitives in a publishing DLS-provider initiated Reset .88
Figure 57 – Sequence of primitives in a subscribing DLS-provider initiated Reset.88
Figure 58 – Sequence of primitives in a simultaneous peer DLS-user and DLS-provider
initiated Reset .88
Figure 59 – Sequence of primitives in a simultaneous publishing DLS-user and DLS-
provider initiated Reset.88
Figure 60 – Sequence of primitives in a simultaneous subscribing DLS-user and DLS-
provider initiated Reset.89
Figure 61 – Sequence of primitives for Subscriber Query.90
Figure 62 – Model for a data-link layer connectionless-mode unitdata transmission or
unitdata exchange .91
Figure 63 – Summary of DL-connectionless-mode service primitive time-sequence

diagrams .94
Figure 64 – State transition diagram for sequences of connectionless-mode primitives at
one DLSAP .95
Figure 65 – Sequence of primitives for a successful locally-acknowledged
connectionless-mode unitdata transfer.98
Figure 66 – Sequence of primitives for a successful remotely-acknowledged
connectionless-mode unitdata transfer.99
Figure 67 – Sequence of primitives for an unsuccessful connectionless-mode unitdata
transfer .99
Figure 68 – Sequence of primitives for connectionless-mode unitdata exchange . 104
Figure 69 – Sequence of primitives for connectionless-mode listener query . 105
Figure 70 – Summary of time and scheduling-guidance service primitive time sequence
diagrams .108
Figure 71 – Sequence of primitives for DL-time . 110
Figure 72 – Sequence of primitives for the Compel-Service service . 112
Figure 73 – Sequence of primitives for the sequence scheduling services. 116
Figure 74 – Sequence of primitives for the DLM action service . 119

Table 1 – Summary of DL(SAP)-address, queue and buffer management primitives and
parameters.28
Table 2 – DL-buffer-and-queue-management create primitive and parameters .30
Table 3 – DL-buffer-and-queue-management delete primitive and parameters .33
Table 4 – DL(SAP)-address-management bind primitive and parameters .34
Table 5 – DL(SAP)-role constraints on DLSAPs, DLCEPs and other DLS Primitives .35
Table 6 – DL(SAP)-address-management unbind primitive and parameters .38
Table 7 – DL-buffer-management put primitive and parameters .39
Table 8 – DL-buffer-and-queue-management get primitive and parameters.40
Table 9 – Relationships between abstract queue model objects .46
Table 10 – Attributes and class requirements of DLCEP data delivery features .52

– 6 – 61158-3-1 © IEC:2007(E)
Table 11 – Summary of DL-connection-mode primitives and parameters (portion 1).57
Table 12 – Summary of DL-connection-mode primitives and parameters (portion 2).58
Table 13 – DLC / DLCEP establishment primitives and parameters (portion 1) .67
Table 14 – DLC / DLCEP establishment primitives and parameters (portion 2) .67
Table 15 – DLC / DLCEP release primitives and parameters.74
Table 16 – Queue data transfer primitive and parameters .79
Table 17 – Buffer sent primitive and parameter.82
Table 18 – Buffer received primitive and parameter .82
Table 19 – DLC/DLCEP reset primitives and parameters (portion 1) .84
Table 20 – DLC/DLCEP reset primitives and parameters (portion 2) .84
Table 21 – Subscriber query primitives and parameters .89
Table 22 – Summary of DL-connectionless-mode primitives and parameters.93
Table 23 – DL-connectionless-mode unitdata transfer primitives and parameters .96
Table 24 – DL-connectionless-mode unitdata exchange primitive and parameters. 100
Table 25 – Listener query primitives and parameters . 105
Table 26 – Summary of DL-scheduling-guidance primitives and parameters. 107
Table 27 – DL-time primitive and parameters. 109
Table 28 – DL-scheduling-guidance Compel-service primitive and parameters. 110
Table 29 – DL-scheduling-guidance Schedule Sequence primitives and parameters . 113
Table 30 – DL-scheduling-guidance Cancel Schedule primitives and parameters . 116
Table 31 – DL-scheduling-guidance Subset Sequence primitives and parameters . 117
Table 32 – Summary of DL-management primitives and parameters . 120
Table 33 – DLM-Set primitive and parameters . 120
Table 34 – DLM-Get primitive and parameters. 121
Table 35 – DLM-Action primitive and parameters. 122
Table 36 – DLM-Event primitive and parameters. 123

61158-3-1 © IEC:2007(E) – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 3-1: Data-link layer service definition – Type 1 elements

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
NOTE  Use of some of the associated protocol types is restricted by their intellectual-property-right holders. In all
cases, the commitment to limited release of intellectual-property-rights made by the holders of those rights permits
a particular data-link layer protocol type to be used with physical layer and application layer protocols in type
combinations as specified explicitly in the IEC 61784 series. Use of the various protocol types in other combinations
may require permission of their respective intellectual-property-right holders.
International Standard IEC 61158-3-1 has been prepared by subcommittee 65C: Industrial
networks, of IEC technical committee 65: Industrial-process measurement, control and
automation.
This first edition and its companion parts of the IEC 61158-3 subseries cancel and replace
IEC 61158-3:2003. This edition of this part constitutes an editorial revision.
This edition includes the following significant changes from the previous edition:
a) deletion of the former Type 6 fieldbus, and the placeholder for a Type 5 fieldbus data-link
layer, for lack of market relevance;
b) addition of new types of fieldbuses;
c) division of this part into multiple parts numbered 3-1, 3-2, …, 3-19.

– 8 – 61158-3-1 © IEC:2007(E)
The text of this standard is based on the following documents:
FDIS Report on voting
65C/473/FDIS 65C/484/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with ISO/IEC Directives, Part 2.
NOTE  Slight variances from the directives have been allowed by the IEC Central Office to provide continuity of
subclause numbering with prior editions.
The committee has decided that the contents of this publication will remain unchanged until the
maintenance result date indicated on the IEC web site under http://webstore.iec.ch in the data
related to the specific publication. At this date, the publication will be:
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
NOTE  The revision of this standard will be synchronized with the other parts of the IEC 61158 series.
The list of all the parts of the IEC 61158 series, under the general title Industrial
communication networks – Fieldbus specifications, can be found on the IEC web site.

61158-3-1 © IEC:2007(E) – 9 –
0 Introduction
0.1 General
This part of IEC 61158 is one of a series produced to facilitate the interconnection of
automation system components. It is related to other standards in the set as defined by the
“three-layer” fieldbus reference model described in IEC/TR 61158-1.
Throughout the set of fieldbus standards, the term “service” refers to the abstract capability
provided by one layer of the OSI Basic Reference Model to the layer immediately above. Thus,
the data-link layer service defined in this standard is a conceptual architectural service,
independent of administrative and implementation divisions.
0.2 Nomenclature for references within this standard
Clauses, including annexes, can be referenced in their entirety, including any subordinate
subclauses, as “Clause N” or “Annex N”, where N is the number of the clause or letter of the
annex.
Subclauses can be referenced in their entirety, including any subordinate subclauses, as “N.M”
or “N.M.P” and so forth, depending on the level of the subclause, where N is the number of the
subclause or letter of the annex, and M, P and so forth represent the successive levels of
subclause up to and including the subclause of interest.
When a clause or subclause contains one or more subordinate subclauses, the text between
the clause or subclause heading and its first subordinate subclause can be referenced in its
entirety as “N.0” or “N.M.0” or “N.M.P.0” and so forth, where N, M and P are as above. Stated
differently, a reference ending with “.0” designates the text and figures between a clause or
subclause header and its first subordinate subclause.
NOTE  This nomenclature provides a means of referencing text in hanging clauses. Such clauses existed in earlier
editions of IEC 61158-3, Type 1 clauses. Those hanging clauses are maintained in this edition to minimize the
disruption to existing national and multi-national standards and consortia documents which reference that prior
subclause numbering.
– 10 – 61158-3-1 © IEC:2007(E)
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 3-1: Data-link layer service definition – Type 1 elements

1 Scope
1.1 Overview
This part of IEC 61158 provides common elements for basic time-critical messaging
communications between devices in an automation environment. The term “time-critical” is
used to represent the presence of a time-window, within which one or more specified actions
are required to be completed with some defined level of certainty. Failure to complete specified
actions within the time window risks failure of the applications requesting the actions, with
attendant risk to equipment, plant and possibly human life.
This standard defines in an abstract way the externally visible service provided by the Type 1
fieldbus data-link layer in terms of
a) the primitive actions and events of the service;
b) the parameters associated with each primitive action and event, and the form which they
take; and
c) the interrelationship between these actions and events, and their valid sequences.
The purpose of this standard is to define the services provided to
• the Type 1 fieldbus application layer at the boundary between the application and data-link
layers of the fieldbus reference model;
• systems management at the boundary between the data-link layer and systems
management of the fieldbus reference model.
1.2 Specifications
The principal objective of this standard is to specify the characteristics of conceptual data-link
layer services suitable for time-critical communications, and thus supplement the OSI Basic
Reference Model in guiding the development of data-link protocols for time-critical
communications. A secondary objective is to provide migration paths from previously existing
industrial communications protocols.
This specification may be used as the basis for formal DL-Programming-Interfaces.
Nevertheless, it is not a formal programming interface, and any such interface will need to
address implementation issues not covered by this specification, including
a) the sizes and octet ordering of various multi-octet service parameters;
b) the correlation of paired request and confirm, or indication and response, primitives.
1.3 Conformance
This standard does not specify individual implementations or products, nor does it constrain the
implementations of data-link entities within industrial automation systems.
There is no conformance of equipment to this data-link layer service definition standard.
Instead, conformance is achieved through implementation of the corresponding data-link
protocol that fulfills the Type 7 data-link layer services defined in this standard.

61158-3-1 © IEC:2007(E) – 11 –
2 Normative references
The following referenced documents are indispensable for the application 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/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference
Model: The Basic Model
ISO/IEC 7498-3, Information technology – Open Systems Interconnection – Basic Reference
Model: Naming and addressing
ISO/IEC 10731:1994, Information technology – Open Systems Interconnection – Conventions
for the definition of OSI services
3 Terms, definitions, symbols, abbreviations and conventions
For the purposes of this document, the following terms, definitions, symbols, abbreviations and
conventions apply.
3.1 Reference model terms and definitions
This standard is based in part on the concepts developed in ISO/IEC 7498-1 and ISO/IEC
7498-3, and makes use of the following terms defined therein.
3.1.1 DL-address [7498-3]
3.1.2 DL-address-mapping [7498-1]
3.1.3 called-DL-address [7498-3]
3.1.4 calling-DL-address [7498-3]
3.1.5 centralized multi-end-point-connection [7498-1]
3.1.6 DL-connection [7498-1]
3.1.7 DL-connection-end-point [7498-1]
3.1.8 DL-connection-end-point-identifier [7498-1]
3.1.9 DL-connection-mode transmission [7498-1]
3.1.10 DL-connectionless-mode transmission [7498-1]
3.1.11 correspondent (N)-entities [7498-1]
correspondent DL-entities  (N=2)
correspondent Ph-entities  (N=1)
[7498-1]
3.1.12 DL-duplex-transmission
[7498-1]
3.1.13 (N)-entity
DL-entity  (N=2)
Ph-entity  (N=1)
3.1.14 DL-facility [7498-1]
3.1.15 flow control [7498-1]
– 12 – 61158-3-1 © IEC:2007(E)
3.1.16 (N)-layer [7498-1]
DL-layer  (N=2)
Ph-layer  (N=1)
3.1.17 layer-management [7498-1]
3.1.18 DL-local-view [7498-3]
3.1.19 DL-name [7498-3]
[7498-3]
3.1.20 naming-(addressing)-domain
[7498-1]
3.1.21 peer-entities
[7498-3]
3.1.22 primitive name
[7498-1]
3.1.23 DL-protocol
[7498-1]
3.1.24 DL-protocol-connection-identifier
[7498-1]
3.1.25 DL-protocol-data-unit
[7498-1]
3.1.26 DL-relay
[7498-1]
3.1.27 reset
[7498-3]
3.1.28 responding-DL-address
3.1.29 routing [7498-1]
3.1.30 segmenting [7498-1]
3.1.31 (N)-service [7498-1]
DL-service  (N=2)
Ph-service  (N=1)
3.1.32 (N)-service-access-point [7498-1]
DL-service-access-point  (N=2)
Ph-service-access-point  (N=1)
[7498-3]
3.1.33 DL-service-access-point-address
[7498-1]
3.1.34 DL-service-connection-identifier
[7498-1]
3.1.35 DL-service-data-unit
[7498-1]
3.1.36 DL-simplex-transmission
[7498-1]
3.1.37 DL-subsystem
[7498-1]
3.1.38 systems-management
[7498-1]
3.1.39 DLS-user-data
61158-3-1 © IEC:2007(E) – 13 –
3.2 Service convention terms and definitions
This standard also makes use of the following terms defined in ISO/IEC 10731 as they apply to
the data-link layer:
3.2.1 acceptor
3.2.2 asymmetrical service
3.2.3 confirm (primitive);
requestor.deliver (primitive)
3.2.4 deliver (primitive)
3.2.5 DL-confirmed-facility
3.2.6 DL-facility
3.2.7 DL-local-view
3.2.8 DL-mandatory-facility
3.2.9 DL-non-confirmed-facility
3.2.10 DL-provider-initiated-facility
3.2.11 DL-provider-optional-facility
3.2.12 DL-service-primitive;
primitive
3.2.13 DL-service-provider
3.2.14 DL-service-user
3.2.15 DLS-user-optional-facility
3.2.16 indication (primitive);
acceptor.deliver (primitive)
3.2.17 multi-peer
3.2.18 request (primitive);
requestor.submit (primitive)
3.2.19 requestor
3.2.20 response (primitive);
acceptor.submit (primitive)
3.2.21 submit (primitive)
3.2.22 symmetrical service
3.3 Data-link service terms and definitions
3.3.1
bridge, DL-router
DL-relay entity which performs selective store-and-forward and routing functions
a) to connect two or more separate DL-subnetworks (links) to form a unified DL-subnetwork
(the extended link), and
b) to provide a means by which two end systems can communicate, when at least one of the

– 14 – 61158-3-1 © IEC:2007(E)
end systems is periodically inattentive to the interconnecting DL-subnetwork;
and also provides time synchronization among the links to which it is forwarding
3.3.2
DLCEP-address
DL-address which designates either
a) one peer DL-connection-end-point; or
b) one multi-peer publisher DL-connection-end-point, and implicitly the corresponding set of
subscriber DL-connection-end-points
where each DL-connection-end-point exists within a distinct DLSAP and is associated with a
corresponding distinct DLSAP-address
NOTE  This is an extension of the use of DL-addresses beyond that specified in ISO/IEC 7498-3 (see Figure 1).
DLS-user-entity
DLS-user-entity
DLS-users
DLCEP DLCEP DLCEP DLCEP
DLSAP DLSAP DLSAP
DLCEP-
address
DLSAP-
DLSAP-
DLCEP- group DL- DLCEP-
address
addresses
addresses address address
DL-layer
DL-entity
DL-path DL-path
PhSAP PhSAP
Ph-layer
NOTE 1  DLSAPs and PhSAPs are depicted as ovals spanning the boundary between two adjacent layers.
NOTE 2  DL-addresses are depicted as designating small gaps (points of access) in the DLL portion of a DLSAP. A
DLCEP-address also designates a specific point of information flow (its DLCEP) within the DLSAP.
NOTE 3  A single DL-entity may have multiple DLSAP-addresses and group DL-addresses associated with a single
DLSAP.
NOTE 4  Figure 1 also shows the relationships of DL-paths and PhSAPs.
Figure 1 – Relationships of DLSAPs, DLSAP-addresses,
DLCEPs, DLCEP-addresses, DLSEP-addresses and group DL-addresses

61158-3-1 © IEC:2007(E) – 15 –
3.3.3
DL-segment, link, local link
single DL-subnetwork in which any of the connected DLEs may communicate directly, without
any intervening DL-relaying, whenever all of those DLEs that are participating in an instance of
communication are simultaneously attentive to the DL-subnetwork during the period(s) of
attempted communication
3.3.4
DLSAP
distinctive point at which DL-services are provided by a single DL-entity to a single higher-layer
entity
NOTE  This definition, derived from ISO/IEC 7498-1, is repeated here to facilitate understanding of the critical
distinction between DLSAPs and their DL-addresses.
3.3.5
DL(SAP)-address
either an individual DLSAP-address, designating a single DLSAP of a single DLS-user, or a
group DL-address potentially designating multiple DLSAPs, each of a single DLS-user
NOTE  This terminology is chosen because ISO/IEC 7498-3 does not permit the use of the term DLSAP-address to
designate more than a single DLSAP at a single DLS-user.
3.3.6
(individual) DLSAP-address
DL-address that designates only one DLSAP within the extended link
NOTE  A single DL-entity may have multiple DLSAP-addresses associated with a single DLSAP.
3.3.7
DLSEP-address
DL-address which designates a DL-scheduling-end-point within a DLE
NOTE  This is an extension of the use of DL-addresses beyond that specified in ISO/IEC 7498-3. (See Figure 1.)
3.3.8
extended link
DL-subnetwork, consisting of the maximal set of links interconnected by DL-relays, sharing a
single DL-name (DL-address) space, in which any of the connected DL-entities may
communicate, one with another, either directly or with the assistance of one or more of those
intervening DL-relay entities
NOTE  An extended link may be composed of just a single link.
3.3.9
frame
denigrated synonym for DLPDU
3.3.10
group DL-address
DL-address that potentially designates more than one DLSAP within the extended link. A single
DL-entity may have multiple group DL-addresses associated with a single DLSAP. A single
DL-entity also may have a single group DL-address associated with more than one DLSAP
3.3.11
initiator
DLE role in which a DLE sends a DLPDU to a peer responder DLE, which immediately sends a
reply DLPDU back to the initiator DLE (and potentially to other DLEs) a
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