1、BRITISH STANDARD BS ISO/IEC 11575:1995 Implementation of BS ISO/IEC 11575:1995 Information technology Telecommunications and information exchange between systems Protocol mappings for the OSI Data Link service ICS 35.100.20 UDC 681.3:621.39BSISO/IEC11575:1995 This British Standard, having been prepa
2、red under the directionof the Information Systems Technology Assembly,was published underthe authority of the Standards Board and comes intoeffect on 15December 1995 BSI 01-2000 The following BSI references relate to the work on this standard: Committee reference IST/6 Draft for comment 92/68500 DC
3、ISBN 0 580 24890 9 Committees responsible for this BritishStandard The preparation of this British Standard was entrusted to Technical Committee IST/6, Data Communications, upon which the following bodies were represented: British Computer Society British Telecommunications plc CCTA (the Government
4、Centre for Information Systems) Digital Equipment Co. Ltd. Institution of Electrical Engineers International Computers Limited Nine Tiles Computer Systems Ltd. Rank Xerox (UK) Ltd. Co-opted members Amendments issued since publication Amd. No. Date CommentsBSISO/IEC11575:1995 BSI 01-2000 i Contents P
5、age Committees responsible Inside front cover National foreword ii Foreword iii Text of ISO/IEC 11575 1BSISO/IEC11575:1995 ii BSI 01-2000 National foreword This British Standard reproduces verbatim ISO/IEC11575:1995 and implements it as the UK national standard. This British Standard is published un
6、der the direction of the Information Systems Technology Assembly whose Technical Committee IST/6 has the responsibility to: aid enquirers to understand the text; present to the responsible international committee any enquiries on interpretation, or proposals for change, and keep UK interests informe
7、d; monitor related international and European developments and promulgate them in the UK. NOTEInternational and European Standards, as well as overseas standards, are available from Customer Services, BSI, 389 Chiswick High Road, London W4 4AL. A British Standard does not purport to include all the
8、necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, the
9、ISO/IECtitle page, pagesii toiv, pages1 to15 and aback cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.ISO/IEC11575:1995 (E) ii BSI 01-2000 Contents Page Foreword iii 1 Scope
10、1 2 Normative references 1 3 Definitions 2 4 Abbreviations 2 5 Conformance 3 6 General principles of the protocol mappings 3 7 Protocol mapping for ISO/IEC7776 single link procedures 6 8 Protocol mapping for HDLC Unbalanced operation Normal response mode Class (UNC) 8 9 Protocol mappings for LLC Typ
11、es 1 and 2 11 10 Protocol mappings for HDLC connectionless-mode classes of procedure 14 Figure 1 Model of Data Link service provision 3 Figure 2 Structure of DLS provider 4 Figure 3 Types of data link configuration 5 Table 1 Mapping between principal ISO/IEC7776 SLP protocolfunctionsandCO-DLS featur
12、es 6 Table 2 Mapping between primitives and ISO/IEC7776 frames atDLCestablishment 7 Table 3 Mapping between primitives and ISO/IEC 7776 frames, etc.,atDLCrelease 7 Table 4 Mapping between primitives and ISO/IEC 7776 frames for DLC reset 8 Table 5 Mapping between principal HDLC UNC protocol functions
13、and CO-DLS features 9 Table 6 Mapping between primitives and HDLC UNC frames at DLCestablishment 9 Table 7 Mapping between primitives and HDLC UNC frames, etc., at DLC release 10 Table 8 Mapping between primitives and HDLC UNC frames for DLC reset 11 Table 9 Mapping between principal LLC Type 2 prot
14、ocol functions and CO-DLS features 12 Table 10 Mapping between primitives and LLC Type 2 PDUs at DLC establishment 12 Table 11 Mapping between primitives and LLC Type 2 PDUs, etc., at DLC release 13 Table 12 Mapping between primitives and LLC Type 2 PDUs for DLC reset 14ISO/IEC11575:1995 (E) BSI 01-
15、2000 iii 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 IECparticipate in the development of International Standards throug
16、h 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 t
17、ake part in the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC1. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires
18、 approval by at least75% of the national bodies casting a vote. International Standard ISO/IEC11575 was prepared by Joint Technical Committee ISO/IEC JTC1, Information technology.iv blankISO/IEC11575:1995 (E) BSI 01-2000 1 1 Scope This International Standard specifies general principles for the mapp
19、ings between the OSI Data Link service (ISO/IEC8886), both connection-mode (CO-DLS) and connectionless-mode (CL-DLS), and standard Data Link protocols, as follows: This International Standard specifies the detailed mappings M1, M2, M5 and M6; it also specifies the main features of the mappings M3 an
20、d M4. This International Standard does not specify individual implementations or products, nor does it constrain the implementation of Data Link entities and interfaces within an information processing system. NOTE 1The above designations M1 to M6 for the mappings are used elsewhere in this Internat
21、ional Standard. NOTE 2The possibility of adding further mappings to the above list in the future is not precluded (for example, to cover Frame Relay protocols). 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this Inte
22、rnational Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards listed below. M
23、embers of IEC and ISO maintain registers of currently valid International Standards. ISO/IEC 3309:1993, Information technology Telecommunications and information exchange between systems High-level data link control (HDLC) procedures Frame structure. ISO/IEC 4335:1993, Information technology Telecom
24、munications and information exchange between systems High-level data link control (HDLC) procedures Elements of procedures. ITU-T Recommendation X.200 (1994)|ISO/IEC 7498-1:1994, Information technology Open Systems Interconnection Basic Reference Model: The basic model. ISO/IEC 7776:1995, Informatio
25、n technology Telecommunications and information exchange between systems High-level data link control procedures Description of the X.25 LAPB-compatible DTE data link procedures. ISO/IEC 7809:1993, Information technology Telecommunications and information exchange between systems High-level data lin
26、k control (HDLC) procedures Classes of procedures. ISO/IEC 8802-2:1994, Information technology Telecommunications and information exchange between systems Local and metropolitan area networks Specific requirements Part 2: Logical link control. ISO/IEC 8886:1992, Information technology Telecommunicat
27、ions and information exchange between systems Data Link service definition for Open Systems Interconnection. ITU-T Recommendation X.210 (1993)|ISO/IEC 10731:1994, Information technology Open Systems Interconnection Basic Reference Model Conventions for the definition of OSI services. M1: CO-DLS HDLC
28、 X.25 LAPB-compatible DTE procedures, single link procedures (ISO/IEC7776) M2: CO-DLS HDLC Unbalanced operation Normal response mode Class, UNC (ISO/IEC3309, ISO/IEC4335 and ISO/IEC7809) M3: CO-DLS Logical link control (LLC) Type 2 (ISO/IEC8802-2) M4: CL-DLS LLC Type 1 (ISO/IEC8802-2) M5: CL-DLS HDL
29、C Balanced operation Connectionless-mode Class, BCC (ISO/IEC3309, ISO/IEC4335 and ISO/IEC7809) M6: CL-DLS HDLC Unbalanced operation Connectionless-mode Class, UCC (ISO/IEC3309, ISO/IEC4335 and ISO/IEC7809)ISO/IEC11575:1995 (E) 2 BSI 01-2000 3 Definitions 3.1 This International Standard uses the foll
30、owing terms defined in ITU-T Rec. X.200|ISO/IEC7498-1: DL-address DL-connection DL-connectionless-mode transmission DL-entity DL-group address DL-layer DL-protocol-data-unit DL-service access point DL-service access point address DL-service-data-unit DL-subsystem 3.2 This International Standard uses
31、 the following terms defined in ITU-T Rec. X.210|ISO/IEC10731: DLS provider DLS user primitive request (primitive) indication (primitive) response (primitive) confirm (primitive) 3.3 For the purposes of this International Standard, the following definitions apply: 3.3.1 frame a DL-PDU 3.3.2 instance
32、 of DL-communication a DL connection or a single DL-connectionless-mode transmission 4 Abbreviations BCC balanced operation connectionless-mode class CL connectionless-mode CO connection-mode DISC disconnect DL Data Link DLC Data Link connection DLS Data Link service DLSAP Data Link service access p
33、oint DLSDU Data Link service data unit DM disconnected mode FRMR frame reject HDLC High-level data link control I information LLC Logical Link Control NRM normal response mode PDU protocol data unit QOS quality of service SABM set asynchronous balanced mode SABME set asynchronous balanced mode exten
34、dedISO/IEC11575:1995 (E) BSI 01-2000 3 5 Conformance There is no direct conformance of equipment to this International Standard considered in isolation. The provisions of this International Standard have normative application to equipment implementing Network-layer protocols that are specified in te
35、rms of their use of the OSI Data Link service. For such Network-layer protocols, this International Standard links the behaviour of the underlying Data Link protocols to the relevant features of the Data Link service, and thus provides the basis for establishing conformance of the Network-layer prot
36、ocol implementations to the specified usage of the Data Link layer. NOTE 1This International Standard therefore functions as “glue” between Network-layer protocol standards, written in terms of their use of the OSI Data Link service, and Data Link protocol standards written usually for historical re
37、asons without reference to the OSI Data Link service. Conformance to such a Data Link protocol standard will be expressed entirely in terms of the procedures and PDUs, etc., specified in that standard; conformance to such a Network-layer standard in respect of its use of the Data Link layer will be
38、expressed in terms of, for example, the transfer of NPDUs as DLSDUs, and (for the CO-DLS) of procedures that apply in the event of DL connection reset or DL connection release. This International Standard specifies precisely how the procedures, etc., of the Data Link protocol in question are to be i
39、nterpreted in terms of the OSI Data Link Service, and therefore establishes a precise relationship between the specifications of the Network-layer protocol and of the Data Link protocol. NOTE 2Use of the OSI Data Link service in Network-layer protocol specifications offers the benefits of layer-inde
40、pendence, in that such a Network-layer specification is available, without change, for use over new or alternative Data Link technologies, provided only that the appropriate mapping is specified between the OSI Data Link service and the relevant Data Link technology. 6 General principles of the prot
41、ocol mappings 6.1 Data Link architecture The OSI Data Link service defines the properties of individual instances of DL-communication between pairs of DLS users. The definition is abstractly expressed in terms of primitives and parameters exchanged, at Data Link service access points (DLSAPs), betwe
42、en each DLS user and a single DLS provider: this is illustrated inFigure 1. Operation of the DLS provider is modelled in terms of the exchange of DL-PDUs, in accordance with DL-protocols, between DL-entities (Figure 2). Each DLSAP is attached to a unique DL-entity; a given DL-entity can have one or
43、more DLSAPs attached to it, depending upon system configuration and the nature of the underlying DL-protocols. When real equipment is considered, a data link consists of two or more stations communicating according to a particular DL-protocol or set of related DL-protocols, together with the interco
44、nnecting media supporting information exchange among the stations. Possible configurations of a real data link (seeFigure 3) include: a) point-to-point data links, with just two stations (mappings M1 and M5 are for protocols used in data links of this type); b) centralized multipoint data links, wit
45、h one station controlling communication between itself and a number of subsidiary stations (mappings M2 and M6 are for protocols used in data links of this type); SLP single link procedure SNRM set normal response mode SNRME set normal response mode extended UA unnumbered acknowledgement UCC unbalan
46、ced operation connectionless-mode class UI unnumbered information UNC unbalanced operation normal response mode class Figure 1 Model of Data Link service provisionISO/IEC11575:1995 (E) 4 BSI 01-2000 c) distributed multipoint data links, with a number of stations any of which can communicate with any
47、 other (local area networks are of this type, see mappings M3 and M4). The definition of stations and data links has a logical dimension, deriving from the protocols used, in addition to the physical equipment used in constructing particular real data links. A single real system can be attached to t
48、wo or more data links, in which case it is considered to contain the corresponding number of distinct stations; a single real system can contain two or more stations attached to the same data link; and it is possible for a single set of communications equipment to support two or more distinct data l
49、inks. The Data Link service model deals primarily with the properties of individual instances of DL-communication, each occurring between a pair of DL-entities or, for multicast communication, between a single originating source DL-entity and a set of destination DL-entities. DL-protocols have to deal with multiple instances of communication, both between a given pair of DL-entities and, certainly for data links of types b) and c) above, between different pairs (or multicast
