1、 Reference number ISO/IEC 13239:2002(E) ISO/IEC 2002INTERNATIONAL STANDARD ISO/IEC 13239 Third edition 2002-07-15 Information technology Telecommunications and information exchange between systems High-level data link control (HDLC) procedures Technologies de linformation Tlcommunications et change
2、dinformation entre systmes Procdures de commande de liaison de donnes haut niveau (HDLC) ISO/IEC 13239:2002(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces whic
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7、i ISO/IEC 2002 All rights reservedISO/IEC 13239:2002(E) ISO/IEC 2002 All rights reserved iiiContents Page Foreword.v Introduction .vi 1 Scope1 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 f
8、ormats11 4.2 Elements of the frame 12 4.3 Transparency15 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 procedures21 5.1 Data link channel states.21 5.2 Modes 22 5.
9、3 Control field formats25 5.4 Control field parameters .27 5.5 Commands and responses .31 5.6 Exception condition reporting and recovery .53 6 HDLC classes of procedures58 6.1 Types of data station 59 6.2 Configurations60 6.3 Operational modes .60 6.4 Addressing scheme.60 6.5 Send and receive state
10、variables .60 6.6 Fundamental classes of procedures 60 6.7 Optional functions62 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.
11、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 functions78 7 General purpose Exchange Identification (XID) frame85 7.1 General purpose XID fram
12、e information field structure .85 7.2 General purpose XID frame information field encoding85 7.3 Single-frame exchange negotiation process91 7.4 Frame check sequence negotiation rules92 7.5 Rules for negotiation use of the frame format field in non-basic frame format mode.93 8 Resolution/negotiation
13、 of data link layer address in switched environments .93 8.1 Operational requirements .93 ISO/IEC 13239:2002(E) iv ISO/IEC 2002 All rights reserved8.2 Address resolution . 94 Annex A (informative) Explanatory notes on the implementation of the frame checking sequence 95 Annex B (informative) Example
14、 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
15、 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 ISO/IEC 13239:2002(E) ISO/IEC 2002 All rights reserved vForeword ISO (the International Organization for Standardiz
16、ation) 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 t
17、o 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 a
18、nd 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
19、 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 su
20、bject 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 e
21、dition 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 i
22、nformation only. ISO/IEC 13239:2002(E) vi ISO/IEC 2002 All rights reservedIntroduction 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 dest
23、ination(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 fra
24、mes 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.
25、 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 combi
26、nation on the data link. The acknowledgement function is accomplished by the data sink informing the data source of the next expected sequence number. This can be done in a separate frame, not containing information, or within the control field of a frame containing information. HDLC procedures are
27、applicable to unbalanced data links and to balanced data links. Unbalanced data links An unbalanced data link involves two or more participating data stations. For control purposes, one data station on the data link assumes responsibility for the organization of data flow and for unrecoverable data
28、link level error conditions. The data station assuming these responsibilities is known as the primary station in unbalanced connection-mode data links and as the control station in unbalanced connectionless-mode data links, and the frames it transmits are referred to as command frames. The other dat
29、a stations on the data link are known as the secondary stations in unbalanced connection-mode data links and as the tributary stations in unbalanced connectionless-mode data links, and the frames they transmit are referred to as response frames. For the transfer of data between the primary/control s
30、tation and the secondary/tributary stations, two cases of data link control are considered (see figures A and B). In the first case, the data station comprising the data source performs a primary/control station data link control function and controls the data station comprising the data sink that i
31、s associated with a secondary/tributary station data link control function, by select-type commands. In the second case, the data station comprising the data sink performs a primary/control station data link control function and controls the data station comprising the data source that is associated
32、 with a secondary/tributary station data link control function, by poll-type commands. The information flows from the data source to the data sink, and the acknowledgements are always transmitted in the opposite direction. These two cases of data link control may be combined so that the data link be
33、comes capable of two-way alternate communication, or two-way simultaneous communication. ISO/IEC 13239:2002(E) ISO/IEC 2002 All rights reserved viiSelect/information Primary/ Control station Secondary/ Tributary station Acknowledgement Data source Data sinkFigure A Unbalanced data link functions (ca
34、se 1) Poll/acknowledgement Primary/ Control station Secondary/ Tributary station Information Data sink Data sourceFigure B Unbalanced data link functions (case 2) Balanced data links A balanced data link involves only two participating data stations. For control purposes, each data station assumes r
35、esponsibility for the organization of its data flow and for unrecoverable data link level error conditions associated with the transmissions that it originates. Each data station is known as a combined station in balanced connection-mode data links and as a peer station in balanced connectionless-mo
36、de data links and is capable of transmitting and receiving both command and response frames. For the transfer of data between combined/peer stations, the data link control functions illustrated in figure C are utilized. The data source in each combined/peer station controls the data sink in the othe
37、r combined/peer station by the use of select-type commands. The information flows from the data source to the data sink, and the acknowledgements are always transmitted in the opposite direction. The poll-type commands may be used by each combined/peer station to solicit acknowledgements and status
38、responses from the other combined/peer station. Combined/ Peer station Combined/ Peer station Data sink/data source Data sink/data source Select/information/acknowledgement/poll Select/information/acknowledgement/pollFigure C Balanced data link functions Data link configurations HDLC classes of proc
39、edures describe methods of data link operation which permit synchronous or start/stop, code-transparent data transmission between data stations in a variety of logical and physical configurations. The classes are defined in a consistent manner within the framework of an overall HDLC architecture. On
40、e of the purposes of this International Standard is to maintain maximum compatibility between the basic types of procedures, unbalanced, balanced and connectionless, as this is particularly desirable for data stations with configurable capability, which may have the characteristics of a primary, sec
41、ondary, combined, control, tributary, or peer station, as required for a specific instance of communication. Five fundamental classes of procedures (two unbalanced, one balanced, and two connectionless) are defined herein. The unbalanced classes apply to both point-to-point and multipoint configurat
42、ions (as illustrated in figure D using the primary/secondary nomenclature) over either dedicated or switched data transmission facilities. A characteristic of the unbalanced classes is the existence of a single primary station at one end of the data link plus one or more secondary stations at the ot
43、her end(s) of the data link. The primary station alone is responsible for data link management, hence the designation “unbalanced“ classes of procedures. ISO/IEC 13239:2002(E) viii ISO/IEC 2002 All rights reservedPrimary/ Control station Secondary/ Tributary station N Secondary/ Tributary station AF
44、igure D Unbalanced data link configuration The unbalanced connectionless class applies to point-to-point configurations over either dedicated or switched data transmission facilities, or to multipoint configurations over dedicated data transmission facilities (as illustrated in figure D using the co
45、ntrol/tributary nomenclature). A characteristic of the unbalanced connectionless class is the existence of a single control station at one end of the data link plus one or more tributary stations at the other end(s) of the data link. The control station is responsible for determining when a tributar
46、y station is permitted to send. Neither the control station nor the tributary station(s) support any form of connection establishment/termination procedures, flow control procedures, data transfer acknowledgement procedures, or error recorvery procedures, hence the designation “connectionless” class
47、 of procedures. The balanced class applies to point-to-point configurations (as illustrated in figure E using the combined nomenclature) over either dedicated or switched data transmission facilities. A characteristic of the balanced class is the existence of two data stations, called combined stati
48、ons, on a logical data link, that may share equally in the responsibility for data link management, hence the designation “balanced“ class of procedures. Combined/ Peer station A Combined/ Peer station B IFigure E Balanced data link configuration The balanced connectionless class applies to point-to
49、-point configurations over either dedicated or switched data transmission facilities (as illustrated in figure E using the peer nomenclature). A characteristic of the balanced connectionless class is the existence of two data stations, called peer stations, on a data link, that are each independently in control of when they can send. Neither peer station supports any form of connection establishment/termination procedures, flow control procedures, data transfer acknowledgement procedures, or error recovery procedures, hence th
