BS ISO IEC 11570-1993 Information technology - Telecommunications and information exchange between systems - Open systems interconnection - Transport protocol identification mechan.pdf

1、BRITISH STANDARD BS ISO/IEC 11570:1992 Implementation of ISO/IEC 11570:1992 Information technology Telecommunications and information exchange between systems Open Systems Interconnection Transport protocol identification mechanism UDC 681.3BSISO/IEC11570:1992 This British Standard, having been prep

2、ared under the directionof the Information Systems Technology Standards Policy Committee, was publishedunder the authorityofthe Standards Boardand comes into effect on 15 August 1993 BSI 01-2000 The following BSI references relate to the work on this standard: Committee reference IST/6 Draft for com

3、ment 92/60186 DC ISBN 0 580 22450 3 Committees responsible for this BritishStandard The preparation of this British Standard was entrusted by the Information Systems Technology Standards Policy Committee (IST/-) to Technical Committee IST/6, upon which the following bodies were represented: British

4、Computer Society British Telecommunications plc CCTA (the Government Centre for Information Systems) Digital Equipment Co Ltd. IBM United Kingdom Ltd. Information Systems Committee of the Universities Funding Council Institution of Electrical Engineers International Computers Limited Logica UK Ltd.

5、Ministry of Defence Rank Xerox Ltd. Swift Project Consortium Amendments issued since publication Amd. No. Date CommentsBSISO/IEC11570:1992 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword ii Foreword iii Text of ISO/IEC 11570 1BSISO/IEC11570:1992 ii BSI 01-2000

6、 National foreword This British Standard reproduces verbatim ISO/IEC11570:1992 and implements it as the UK national standard. This British Standard is published under the direction of the Information Systems Technology Standards Policy Committee whose Technical Committee IST/6 has the responsibility

7、 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 informed; monitor related international and European developments and promulgate them in the UK. NOTEInternational and Europea

8、n Standards, as well as overseas standards, are available from Customer Services, Publications, BSI, Linford Wood, Milton Keynes, MK14 6LE. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct applicat

9、ion. 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, theISO/IEC title page, pagesii toiv, pages1 to5 and abackcover. This standard has been updated (see copyrigh

10、t date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.ISO/IEC11570:1992(E) ii BSI 01-2000 Contents Page Foreword iii Introduction 1 1 Scope 1 2 Normative references 1 3 Definitions 1 4 Symbols and abbreviations 1 5 Use of the networ

11、k service 1 6 Protocol functions 2 7 Structure and encoding of the UN TPDU 2 8 Conformance 3 Annex A (normative) PICS Proforma 4ISO/IEC11570:1992(E) BSI 01-2000 iii Foreword ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the spec

12、ialized system for worldwide standardization. National bodies that are members of ISO or IECparticipate 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 co

13、mmittees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take partin the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC1. Draft Inter

14、national Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires approval by at least75% of the national bodies casting a vote. International Standard ISO/IEC11570 was prepared by Joint Technical Committee ISO

15、/IEC JTC1, Information technology. Annex A forms an integral part of this International Standard.iv blankISO/IEC11570:1992(E) BSI 01-2000 1 Introduction This International Standard is one of a set of International Standards produced to facilitate the interconnection of information processing systems

16、. This set of International Standards covers the services and protocols required to achieve such interconnection. The identification mechanism of transport protocols is positioned with respect to other related International Standards by the layer defined in the reference model for open system interc

17、onnection (ISO7498). It allows identification of protocols (bothOSI and non-OSI) used on a given network connection. The initiating transport entity of a network connection may indicate to the accepting transport entity, what transport protocol is to be used on the network connection. 1 Scope The pr

18、ocedures specified in this International Standard do not prevent communication between transport entities conforming to ISO/IEC8073 only and those conforming to ISO/IEC8073 as well as to this International Standard. The use of a protocol identification procedure allows transport entities to be imple

19、mented which can support both the OSI transport protocols and non-OSI protocols above the OSI network layer. NOTEThe use of NSAP addresses as it is defined in ISO/IEC7498-3 provides another possibility in distinguishing between OSI and non-OSI users of the network service. If however the use of NSAP

20、s incurs unacceptable penalties, for example where each NSAP is charged for by the network provider, then the transport protocol identification mechanism is available. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of th

21、is International 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 b

22、elow. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 7498:1984, Information processing systems Open Systems Interconnection Basic Reference Model. ISO 7498-3:1989, Information processing systems Open Systems Interconnection Basic Reference Model Part 3: Nam

23、ing and addressing. ISO 8072:1986, Information processing systems Open Systems Interconnection Transport service definition. ISO/IEC 8073:1992, Information technology Telecommunications and information exchange between systems Open Systems Interconnection Protocol for providing the connection-mode t

24、ransport service. ISO/IEC 8348:1992, Information processing systems Data communications Network service definition. ISO 8602:1986, Information processing systems Open Systems Interconnection Protocol for providing the connectionless-mode transport service. ISO/IEC 10736:1992, Information technology

25、Telecommunications and information exchange between systems Transport layer security protocol. CCITT Recommendation X.25, Interface between data terminal equipment (DTE) and data circuit-terminating equipment (DCE) for terminals operating in the packet mode and connected to public data networks by d

26、edicated circuit. CCITT Recommendation X.244, Procedure for the exchange of protocol identification during virtual call establishment on packet switched public data networks. 3 Definitions The following terms are used by this International Standard and are defined by ISO 7498: Open Systems Interconn

27、ection (OSI); network connection; transport entity. 4 Symbols and abbreviations 4.1 Transport protocol data unit 4.2 TPDU fields 5 Use of the network service Transport protocol identification makes use of the network service defined in ISO8348. It uses the NS-user data parameter of the N-CONNECT req

28、uest and indication primitive only. UN TPDU Use of network connection TPDU LI Length indicator (field) SHARE Sharing option (field) PRT-ID Protocol identifier (field)ISO/IEC11570:1992(E) 2 BSI 01-2000 6 Protocol functions 6.1 Default identification When using default identification, no NS-user data

29、parameter shall be placed in the N-CONNECT request primitive. ISO/IEC8073 is then identified. 6.2 Explicit identification When using explicit identification, an UN TPDU shall be placed in the NS-user data parameter of the N-CONNECT request primitive. This UN TPDU may be followed by other PDUs, which

30、 are recognizable by the identified protocol, in the NS-user data parameter of the N-CONNECT request primitive. The sending transport entity shall a) set the PRT-ID field of the UN TPDU to the value assigned in7.3 to the protocol used; b) set the SHARE field of the UN TPDU to the value00000000 (no s

31、haring); c) not use the variable part of the UN TPDU; NOTEThis International Standard does not include procedures for sharing a network connection between different protocols. The following strategies could be used in the future: a) sequential reuse of a network connection by several protocols (i.e.

32、consecutive sharing); b) concurrent use of a network connection by several protocols (i.e.concurrent sharing). Inclusion of these strategies will use other values of the SHARE field and may make use of the variable part of the UN TPDU. 6.3 Protocol operation The receiving transport entity shall oper

33、ate the protocol, identified either by default or explicitly, ifit is claimed that this protocol is supported. Otherwise the network connection shall be refused. 7 Structure and encoding of the UN TPDU The length of the UN TPDU shall not exceed32octets. NOTEThis is a restriction imposed on future en

34、hancements to this TPDU by constraints within the Network Layer. This restriction on the length of the parameter is due to the desire not to conflict with the protocol identifier field carried by X.25 CALL requests. This is a single octet located at the same position as the length indicator of the U

35、N TPDU when the latter is carried in anX.25 CALL request. CCITT have already chosen value for this parameter and thus it is important not to use those values (seeCCITT Recommendation X.244). 7.1 Structure The structure of the UN TPDU shall be as follows: 7.2 Length indicator (LI) field The field is

36、contained in the first octet of the TPDUs. The length is indicated by a binary number, with a maximum value of254(11111110). The length indicated shall be the header length in octets including parameters, but excluding the length indicator field and user data, if any. The value255(11111111) is reser

37、ved for possible extensions. If the length indicated exceeds or is equal to the size of the NS-user data which is present, this is a protocol error. 7.3 Fixed part The fixed part shall be as follows: a) UN: UN TPDU code:00000001; b) PRT-ID: protocol identifier; Values: c) SHARE: sharing strategy. Va

38、lues: 7.4 Variable part The variable part consists of one optional parameter. This parameter is only present when SHARE is different from 00000000. 1 2 3 4 5 to p LI UN 00000001 PRT-ID SHARE Variable part 00000000 Reserved 00000001 ISO/IEC 8073 00000010 ISO 8602 00000011 ISO/IEC 10736 in conjunction

39、 with ISO/IEC 8073 00000100 ISO/IEC 10736 in conjunction with ISO 8602 00000101 through Reserved for other OSI protocols 01111111 10000000 through Reserved for private use 11111111 00000000 No sharing 1 2 3 to p PRT-ID LIST LENGTH VALUES 11011111 1 to 26 TYPE = PRT-ID LIST (11011111), Length = numbe

40、r of PRT-IDs, Value = list of PRT-IDs, one per octet.ISO/IEC11570:1992(E) BSI 01-2000 3 8 Conformance A system claiming to conform to this International Standard shall comply with the requirements of8.1 and 8.2. 8.1 When initiating a network connection a transport entity shall either a) not use the

41、NS-user data parameter of N-CONNECT request primitive and operate using the protocol of ISO/IEC8073 on this network connection; or b) include a UN TPDU in the NS-user data parameter of the N-CONNECT request primitive and operate using the transport protocol specified in the PRT-ID parameter of the U

42、N TPDU. 8.2 When processing an N-CONNECT indication, a transport entity shall a) regard ISO/IEC 8073 as being identified if no UN TPDU is present; or b) accept the PRT-ID field of the UN TPDU if the UN TPDU is present; and operate the identified protocol if it is claimed that this protocol is suppor

43、ted, otherwise reject the network connection.ISO/IEC11570:1992(E) 4 BSI 01-2000 Annex A (normative) Protocol Implementation Conformance Statement (PICS) Proforma 1) A.1 General A.1.1 Symbols used Status symbols: Support symbols: A.1.2 Instructions for completing the PICS proforma The main part of th

44、e PICS proforma is a fixed-format questionaire divided into a number of clauses. Answers to the questionnaire are to be provided in the rightmost column either by simply marking an answer to indicate a restricted choice (such as Yes or No) or by entering a value of a range of values or entering what

45、 action is taken. A.2 Supported TPDU P1: The only transport protocol claimed to be supported is ISO/IEC8073. A.3 Supported parameters of issued UN TPDU A.4 Supported parameters for received UN TPDU 1) Copyright release for PICS proforma Users of this International Standard may freely reproduce the P

46、ICS proforma in this annex so that it can be used for its intended purpose and may further publish the completed PICS. M Mandatory. O Optional to implement. If implemented the feature may or may not be used. Yes Supported. No Not supported. N/A Not applicable. Index TPDU References Status Support ST

47、1 UN supported on transmission 6.2 P1:O NOT P1:M YesNo ST2 UN transmitted, when identifying ISO/IEC 8073 6.2, 6.1 ST1:O YesNoN/A ST3 UN supported on receipt 6.3 M Yes Index Supported parameters References Allowed values Supported values IU1 Protocol identifier 7.3 b) ISO/IEC 8073; ISO 8602; ISO/IEC

48、10736 in conjunction with ISO/IEC 8073; ISO/IEC 10736 in conjunction with ISO 8602; Private:10000000,., 11111111 IU2 Sharing strategy 7.3 c) No sharing Index Supported parameters References Allowed values Supported values RU1 Protocol identifier 7.3 b) ISO/IEC 8073; ISO 8602; ISO/IEC 10736 in conjun

49、ction with ISO/IEC 8073; ISO/IEC 10736 in conjunction with ISO 8602; Private:10000000,., 11111111 RU2 Sharing strategy 7.3 c) No sharingISO/IEC11570:1992(E) BSI 01-2000 5 A.5 Actions on protocol identification P2: It is claimed to support the identified protocol. Index Event References Status Support PI1 Absence of a UN TPDU in an N-CONNECT indication is regarded as identifying ISO/IEC 8073 6.1 M Yes PI2 Operate the identified protocol 6.1, 6.3 P2:M Yes PI3 Refuse the network connection 6.3 NOT P2:M YesBS ISO/IEC 11570:1992 BSI 389 Chis