ISO/IEC 13239:2002

Information technology — Telecommunications and information exchange between systems — High-level data link control (HDLC) procedures

This International Standard specifies the frame structures, the elements of procedures, the classes of procedures, the content and format of the general purpose Exchange Identification (XID) frame, and a means for resolution/negotiation of a data link layer address in switched environments for data communication systems using bit-oriented high-level data link control (HDLC) procedures. NOTE The use of the phrase "bit-oriented", referring to the HDLC control procedures, pertains to the allocation of a non-integral number of bits to various subfields used for HDLC control purposes. However, the frame as an entirety may be constructed from octet-oriented units (e.g., start-stop mode) for transmission purposes. The frame structure portion defines the relative positions of the various components of the basic frame format and the nonbasic frame format. The mechanisms used to achieve bit pattern independence (transparency), where and when required, within the frame are also defined. In addition, three frame checking sequences (FCS) are specified; the rules for address field extension are defined; and the addressing conventions available are described. The elements of procedures portion specifies elements of data link control procedures for synchronous or start/stop, codetransparent data transmission using independent frame numbering in both directions. These HDLC elements of procedures are defined specifically in terms of the actions that occur on receipt of commands at a secondary station, a tributary station, a peer station, or a combined station. This International Standard is intended to cover a wide range of applications; for example one-way, two-way alternate or twoway simultaneous data communication between data stations which are usually buffered, including operations on different types of data circuits; for example multipoint/point-to-point, duplex/half-duplex, switched/non-switched, synchronous/startstop, etc. The defined elements of procedures are to be considered as a common basis for establishing different types of data link control procedures. This International Standard does not define any single system and should not be regarded as a specification for a data communication system. Not all of the commands or responses are required for any particular system implementation. The classes of procedures portion describes the HDLC unbalanced classes of procedures, the HDLC balanced class of procedures, and the HDLC connectionless classes of procedures for synchronous or start/stop data transmission. For the unbalanced classes, the data link consists of a primary station plus one or more secondary stations and operates in either the normal response mode or the asynchronous response mode in a point-to-point or multipoint configuration. For the balanced class, the data link consists of two combined stations and operates in the asynchronous balanced mode in a point-topoint configuration. For the unbalanced connectionless class, the data link consists of a control station plus one or more tributary stations and operates in the unbalanced connectionless-mode in a point-to-point or multipoint configuration. For the balanced connectionless class, the data link consists of two peer stations and operates in the balanced connectionless-mode in a point-to-point configuration. In each class, a basic repertoire of commands and responses is defined, but the capability of the data link may be modified by the use of optional functions. Balanced operation is intended for use in circumstances which require equal control at either end of the data link. Operational requirements are covered in accordance with the overall HDLC architecture. The content and format of the Exchange Identification (XID) frame portion builds on the fact that the principal use of the XID frame is to exchange data link information between two or more HDLC stations. For the purpose of this International Standard, ISO/IEC 13239:2002(E)

Technologies de l'information — Télécommunications et échange d'information entre systèmes — Procédures de commande de liaison de données à haut niveau (HDLC)

General Information

• Status: Published
• Publication Date: 21-Aug-2002
• ICS: 35.100.20 - Data link layer
• Technical Committee: ISO/IEC JTC 1/SC 6 - Telecommunications and information exchange between systems
• Drafting Committee: ISO/IEC JTC 1/SC 6 - Telecommunications and information exchange between systems
• Current Stage: 9093 - International Standard confirmed
• Completion Date: 20-Dec-2007

Relations

• Revises: ISO/IEC 13239:2000 - Information technology — Telecommunications and information exchange between systems — High-level data link control (HDLC) procedures
• Effective Date: 15-Apr-2008
• Revises: ISO/IEC 4335:1993 - Information technology —- Telecommunications and information exchange between systems — High-level data link control (HDLC) procedures — Elements of procedures
• Effective Date: 15-Apr-2008
• Revises: ISO/IEC 7809:1993 - Information technology — Telecommunications and information exchange between systems — High-level data link control (HDLC) procedures — Classes of procedures
• Effective Date: 15-Apr-2008
• Revises: ISO/IEC 8885:1993 - Information technology — Telecommunications and information exchange between systems — High-level data link control (HDLC) procedures — General purpose XID frame information field content and format
• Effective Date: 15-Apr-2008
• Revises: ISO/IEC 3309:1993 - Information technology — Telecommunications and information exchange between systems — High-level data link control (HDLC) procedures — Frame structure
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 13239
Third edition
2002-07-15
Information technology —
Telecommunications and information
exchange between systems — High-level
data link control (HDLC) procedures
Technologies de l'information — Télécommunications et échange
d'information entre systèmes — Procédures de commande de liaison de
données à haut niveau (HDLC)
Reference number
©
ISO/IEC 2002
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO/IEC 2002
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.ch
Printed in Switzerland
ii © ISO/IEC 2002 – All rights reserved

Contents Page
Foreword.v
Introduction .vi
1 Scope.1
2 Normative references .2
3 Definitions, acronyms and abbreviations.3
3.1 Definitions.3
3.2 Acronyms and abbreviations.8
4 HDLC frame structure .10
4.1 Frame formats .11
4.2 Elements of the frame .12
4.3 Transparency.15
4.4 Transmission considerations .17
4.5 Inter-frame time fill .17
4.6 Invalid frame .17
4.7 Extensions .18
4.8 Addressing conventions .18
4.9 Frame format field .19
5 HDLC elements of procedures .21
5.1 Data link channel states .21
5.2 Modes .22
5.3 Control field formats.25
5.4 Control field parameters .27
5.5 Commands and responses .31
5.6 Exception condition reporting and recovery .53
6 HDLC classes of procedures.58
6.1 Types of data station .59
6.2 Configurations.60
6.3 Operational modes .60
6.4 Addressing scheme.60
6.5 Send and receive state variables .60
6.6 Fundamental classes of procedures .60
6.7 Optional functions.62
6.8 Consistency of classes of procedures .62
6.9 Conformance to the HDLC classes of procedures.62
6.10 Method of indicating classes and optional functions.63
6.11 Unbalanced operation (point-to-point and multipoint) .66
6.12 Balanced operation (point-to-point) .69
6.13 Unbalanced connectionless operation (point-to-point and multipoint) .73
6.14 Balanced connectionless operation (point-to-point).76
6.15 Uses of the optional functions.78
7 General purpose Exchange Identification (XID) frame.85
7.1 General purpose XID frame information field structure .85
7.2 General purpose XID frame information field encoding.85
7.3 Single-frame exchange negotiation process.91
7.4 Frame check sequence negotiation rules .92
7.5 Rules for negotiation use of the frame format field in non-basic frame format mode.93
8 Resolution/negotiation of data link layer address in switched environments .93
8.1 Operational requirements .93
© ISO/IEC 2002 – All rights reserved iii

8.2 Address resolution . 94
Annex A (informative) Explanatory notes on the implementation of the frame checking sequence . 95
Annex B (informative) Example of the use of commands and responses . 97
Annex C (informative) Time-out function considerations for NRM, ARM and ABM . 118
Annex D (informative) Examples of typical HDLC procedural subsets. 120
Annex E (informative) Illustrative examples of 16/32-bit FCS negotiation . 123
Annex F (informative) Guidelines for communicating with LAPB X.25 DTEs. 125
Annex G (informative) Examples of information field encoding in multi-selective reject frames . 126
Annex H (normative) Frame format types. 127

iv © ISO/IEC 2002 – All rights reserved

Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the
specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the
development of International Standards through technical committees established by the respective organization to deal with
particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other
international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work. In
the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
The main task of the joint technical committee is to prepare International Standards. Draft International Standards adopted by
the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires
approval by at least 75 % of the national bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 13239 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 6,
Telecommunications and information exchange between systems.
This third edition cancels and replaces the second edition (ISO/IEC 13239:2000), which has been technically revised. It also
cancels and replaces ISO/IEC 3309:1993, ISO/IEC 4335:1993, ISO/IEC 7809:1993 and ISO/IEC 8885:1993.
Annex H forms a normative part of this International Standard. Annexes A to G are for information only.

© ISO/IEC 2002 – All rights reserved v

Introduction
This third edition adds a new frame format type to Annex H – Frame format types. This frame format type is used in those
environments where additional error protection, identification of both the source and the destination(s), and/or longer frame
sizes are needed.
High-level data link control (HDLC) procedures are designed to permit synchronous or start/stop, code-transparent data
transmission. The normal cycle of the code-transparent data communication between two data stations consists of the transfer
of frames containing information from the data source to the data sink acknowledged by a frame in the opposite direction.
Generally, until the data station comprising the data source receives an acknowledgement, it holds the original information in
memory in case the need should arise for retransmissions.
In those situations that require it, data sequence integrity between the data source and the data sink is effected by means of a
numbering scheme, which is cyclic within a specified modulus and measured in terms of frames. An independent numbering
scheme is used for each data source/data sink combination on the data link.
The acknowle
...