1、 ITU-T RECMN*X.215 95 H 48b2573 Ob32703 850 H INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS OPEN SYSTEMS INTERCONNECTION - SERVICE DEFINITIONS X.215 (1 1/95) INFORMATION TECHNOLOGY - OPEN SYSTEMS INTERCONNECTI
2、ON - SESSION SERVICE DEFINITION ITU-T Recommendation X.215 (Previously “CCITT Recommendation”) FOREWORD ITU (Intemational Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent orga
3、n of the ITU. Some 179 member countries, 84 telecom operating entities, 145 scientific and industrial organizations and 38 international organizations participate in ITU-T which is the body which sets world telecommunications standards (Recommendations). The approval of Recommendations by the Member
4、s of IT-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, 1993). In addition, the World Telecommunication Standardization Conference (WTSC), which meets every four years, approves Recommendations submitted to it and establishes the study programme for the following period.
5、In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. The text of ITU-T Recommendation X.215 was approved on the 21st of November 1995. The identical text is also published as ISODEC International Sta
6、ndard 8326. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O ITU 1996 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any mean
7、s, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS Subject area PUBLIC DATA NETWORKS (February 1994) Recommendation Series ORGANIZATION OF X-SERIES RECOMMENDATIONS
8、Network Aspects Maintenance X.90-X. 149 X. 150-X. 179 I Services and Facilities I X. l-X. 19 I Administrative Arrangements OPEN SYSTEMS INTERCONNECTION I Interfaces X. 180-X. 199 X.20-X.49 1 Model and Notation Service Definitions I Transmission, Signalling and Switching I X.50-X.89 I X.200-X.209 X.2
9、10-X.219 - PICS Profomas Protocol Identification _ X.240-X.259 X.260-X.269 Security Protocols Layer Managed Objects Conformance Testing I Connection-mode Protocol SDecifications I X.220-X.229 I X.270-X.279 X.280-X.289 X.290-X.299 I Connectionless-mode Protocol Specifications I X.230-X.239 I INTERWOR
10、KING BETWEEN NETWORKS General Mobile Data Transmission Systems X.300-X.349 X.350-X.369 Management MESSAGE HANDLING SYSTEMS _ 1 X.370-X.399 X.400-X.499 Naming, Addressing and Registration Abstract Syntax Notation One (ASN.1) X.500-X. 599 DIRECTORY OS1 NETWORKING AND SYSTEM ASPECTS X.650-X.679 X.680-X
11、.699 1 Networking I X.600-X.649 I OS1 MANAGEMENT SECUFUTY X.700-X.799 X.800-X.849 OS1 APPLICATIONS Commitment, Concurrency and Recovery Transaction Processing X.850-X.859 X.860-X.879 I Remote Operations 7 X.880-X.899 I I OPEN DISTRIBUTED PROCESSING I X.900-X.999 I ITU-T RECMN*X-215 95 = YB62591 Ob12
12、710 345 CONTENTS SECTION 1 . GENERAL 1 2 3 4 5 6 7 8 9 Scope . Normative references . 2.1 Identical Recommendations I International Standards 2.2 Definitions 3.1 Reference Model definitions . 3.2 Service convention definitions 3.3 Session service definitions Abbreviations . 4.1 Data units 4.2 Miscel
13、laneous . 4.3 Service variables . . . Conventions Model of the session service Paired Recommendations I International Standards equivalent in technical content 6.1 Model of the layer service . 6.2 Overview of the session service . 7.1 General overview . 7.2 Token concept . . 7.4 Activity concept . M
14、odel of session connectionless-mode transmission . 7.3 Synchronization and dialogue unit concepts . 7.5 Resynchronization . 7.6 Negotiation Negotiation of functional units . Negotiation of initial token settings Negotiation of initial synchronization point serial number . 7.6.1 7.6.2 7.6.3 Phases an
15、d services of the session service . 8.1 Session connection establishment phase . 8.2 Data transfer phase . . 8.3 Session connection release phase . Functional units and subsets . 9.1 Functional units . 9.1.1 9.1.2 9.1.3 9.1.4 9.1.5 9.1.6 9.1.7 9.1.8 9.1.9 Kernel functional unit . Negotiated release
16、functional unit . Half-dupiex functional unit . Duplex functional unit . Expedited data functional unit Typed data functional unit Capability data exchange functional unit Minor synchronize functional unit Symmetric synchronize functional unit ITU-T Rec . X.215 (1995 E) Page 1 1 1 1 2 2 2 2 2 3 3 3
17、3 3 4 4 4 4 4 4 5 5 6 6 6 7 7 7 7 7 9 9 9 IO 10 II 11 11 11 11 11 11 i P 9.1.10 Data separation functional unit . . 9.1.1 1 Major synchronize functional unit 9.1.12 Resynchronize functional unit 9.1.13 Exceptions functional unit 9.1.14 Activity management functional unit 9.2 Subsets . Quality of ses
18、sion service . 10 10.1 Determination of QOS 10.2 Session connection QOS negotiation procedures 10.3 Definition of QOS parameters 10.3.2 10.3.1 Session connection establishment delay Session connection establishment failure probability . 10.3.3 Throughput . . 10.3.4 Transit delay 10.3.5 Residual erro
19、r rate . 10.3.6 Transfer failure probability . 10.3.7 Session connection release delay 10.3.8 Session connection release failure probability 10.3.9 Session connection protection . 10.3.1 1 Session connection resilience 10.3.12 Extended control parameter 10.3.13 Optimized dialogue transfer SECTION 2
20、- DEFINITION OF CONNECTION-ORIENTED SESSION SERVICE PRIMITIVES . 11 Introduction to session service primitives 11.1 Summary of primitives 11.2 Token restrictions on sending primitives 11.3 Sequencing of primitives . 1 1.4 Synchronization point senal number management . 11.4.1 1 1.4.2 10.3.10 Priorit
21、y Management of single serial synchronization point numbers . Management of symmetric serial number synchronization point numbers . 12 Session connection establishment phase . 12.1 Session connection service 12.1.1 Function . . 12.1.2 Types of primitiv d their parameters . 12.1.3 Sequence of primiti
22、ves 13 Data transfer phase Normal data transfer service . 13.1.1 Function 13.1.2 Types of primitives and their parameters 13.1.3 Sequence of primitives 13.2 Expedited data transfer service . . 13.2.1 Function 13.2.2 Types of primitives and their parameters . 13.2.3 Sequence of primitives . Typed dat
23、a transfer service 13.3.1 Function . . 13.3.2 Types of primitives arameters . 13.3.3 Sequence of primitives 13.4 Capability data exchange service . 13.4.1 Function 13.4.2 Types of primitives and their parameters . 13.1 13.3 13.4.3 Sequence of primitives age II 11 11 11 11 12 12 12 13 14 14 14 15 15
24、15 16 16 17 17 17 17 17 17 18 18 18 20 21 21 22 24 27 27 27 27 30 30 30 30 30 30 31 31 31 31 32 32 32 32 32 32 32 33 11 ITU-T Rec . X.215 (1995 E) 14 15 16 13.5 13.6 13.7 13.8 13.9 Give tokens service . 13.5.1 Function 13.5.2 Please tokens service . 13.6.1 Function . 13.6.2 Give control service 13.7
25、.1 Function 13.7.2 13.7.3 Sequence of primitives 13.8.1 Function . . 13.8.2 Types of primitives and their parameters 13.5.3 Sequence of primitives Types of primitives and their parameters 13.6.3 Sequence of primitives . . Types of primitives and their parameters Minor synchronization point service .
26、 13.8.3 Sequence of primitives Major synchronization point service 13.9.3 Sequence of primitives . Types of primitives and their parameters 13.9.1 Function . 13.9.2 Types of primitives and their parameters . . . 13.10 Resynchronize service 13.10.1 Function . 13.10.2 Types of primitives and their par
27、ameters . 13.10.3 Sequence of primitives P-exception reporting service 13.12 U-exception-reporting service . 13.13 Activity start service 13.14 Activity resume service . 13.15 Activity interrupt service 13.16 Activity discard service 13.17 Activity end service Session connection release phase . 14.1
28、 Orderly release service . 14.2 U-abort service 14.3 P-abort service 13.1 1 . Sequences of primitives . 15.1 State tables 15.2 Sequences of primitiv t 16.1 Collision as viewed by the SS-user 16.2 . Collision resolution by the SS-provider SECTION 3 . DEFINITION OF CONNECTIONLESS-MODE SESSION SERVICE
29、PRIMITIVES 17 S-UNIT-DATA 17 .i Function . 17.2 Types of Primitives and Parameters 17.3 Sequence of Primitives Annex A - State tables . . A . 1 General A.2 Notation for state tables A.3 Conventions for entries in state tables A.4 Actions to be taken by the SS-user . AS Definitions of sets and variab
30、les . ITU-T Rec . X.215 (1995 E) Page 33 33 33 34 34 34 34 35 35 35 35 36 36 36 37 37 38 38 39 39 40 40 41 42 43 44 46 47 48 49 51 52 52 53 54 55 55 55 55 55 55 57 57 57 57 58 59 59 59 59 60 60 . 111 Summary This Recommendation I International Standard specifies the services which are provided by th
31、e session layer to the presentation layer at the boundary between the session layer and the presentation layer of the OS1 reference model. This includes: a) b) c) the primitive actions and events of the service; the parameters associated with each primitive action and event; and the relationship bet
32、ween the valid sequence of these actions and events. iv ITU-T Rec. X.215 (1995 E) I I Introduction Session protocol I This Recommendation I International Standard is one of a set of Recommendations I International Standards produced to facilitate the interconnection of computer systems. v A Session
33、service Provides serLice based on setvice prwided I This Recommendation I International Standard is related to other Recommendations I International Standards in the set as defined by the Reference Model for Open Systems Interconnection. The Reference Model subdivides the area of standardization for
34、 interconnection into a series of layers of specification, each of manageable size. The purpose of this Recommendation I International Standard is to define the service provided to the Presentation Layer at the boundary between the Session and Presentation Layers of the Reference Model. The session
35、service is provided by the session protocol making use of the services available from the Transport Layer. This Recommendation I International Standard also defines the session service characteristics which the presentation protocol may exploit. The relationship between the Recommendations I Interna
36、tional Standards for the session service, session protocol, transport service, and the presentation protocol is illustrated in Figure Intro. 1 below. It is recognized that, with respect to session Quality of Service (described in clause lo), work is still in progress to provide an integrated treatme
37、nt of QOS across all of the layers of the OS1 Reference Model and to ensure that the individual treatments in each layer service satisfy overall QOS objectives in a consistent manner. As a consequence, an addendum may be added to this Recommendation i International Standard at a later time which ref
38、lects further QOS developments and integration. Figure Intro. 1 - Relationship of this Recommendation i International Standard to other OS1 Standards ITU-T Rec. X.215 (1995 E) V ITU-T RECMN*X.215 95 48b2591 0612716 Ab3 ISO/IEC 8326 : 1996 (E) INTERNATIONAL STANDARD ITU-T RECOMMENDATION INFORMATION T
39、ECHNOLOGY - OPEN SYSTEMS INTERCONNECTION - SESSION SERVICE DEFINITION SECTION 1 - GENERAL 1 Scope This Recommendation i International Standard defines in an abstract way the externally visible service provided by the OS1 Session Layer in terms of a) b) c) the primitive actions and events of the serv
40、ice; the parameter data associated with each primitive action and event; the relationship between, and the valid sequence of these actions and events. The service defined in this Recommendation I International Standard is that which is provided by the OS1 session protocol (in conjunction with the tr
41、ansport service) and which may be used by the OS1 presentation protocol. This Recommendation I International Standard does not specify individual implementations or products, nor does it constrain the implementation of entities and interfaces within a computer system. There is, therefore, no conform
42、ance to this Recommendation I International Standard. The text pertaining to the symmetric synchronization functional unit is not applicable to the support of ITU-T applications. 2 Normative references The following Recommendations and International Standards contain provisions which, through refere
43、nce in this text, constitute provisions of this Recommendation I International Standard. At the time of publication, the editions indicated were valid. All Recommendations and International Standards are subject to revision, and parties to agreements based on this Recommendation I International Stan
44、dard are encouraged to investigate the possibility of applying the most recent edition of the Recommendations and International Standards listed below. Members of IS0 and IEC maintain registers of currently valid International Standards. The Telecommunication Standardization Bureau of the ITU mainta
45、ins a list of currently valid ITU-T Recommendations. 2.1 Identical Recommendations I International Standards - ITU-T Recommendation X.200 (1994) I ISOIEC 7498-1: 1994, Information technology - Open Systems Interconnection - Basic Reference Model: The Basic Model. ITU-T Recommendation X.210 (1993) I
46、ISO/IEC 1073 1: 1994, Information technology - Open Systems Interconnection - Basic Reference Model: Conventions for the definition of OS1 services. ITU-T Recommendation X.214 (1993) I ISO/IEC 8072: 1994, Information technology - Open Systems Interconnection - Transport service dejnition. ITU-T Reco
47、mmendation X.225 (1995) I ISO/IEC 8327-1 : 1996, Information technology - Open Systems Interconnection - Connecrion-oriented Session protocol: Protocol specification. - - - ITU-T Rec. X.215 (1995 E) 1 ITU-T RECMN*X.ZLS 95 m 4862593 Ob12717 7TT = ISO/IEC 8326 : 1996 (E) - ITU-T Recommendation X.226 (
48、1994) I ISOIIEC 8823- 1 : 1994, Inforniarion technology - Open Sxsterns Interconnection - Connection-oriented presentation protocol: Protocol specification. ITU-T Recommendation X.235 (1995) I ISOIIEC 9548-1:1995, Information technology - Open Systems Interconnection - Connectionless Session protoco
49、l: Protocol specification. - 2.2 Paired Recommendations I International Standards equivalent in technical content - CCITT Recommendation X.650 (1992), Open Systems Interconnection (OSI) - Reference Model for naming and addressing. IS0 7498-3: 1989, Information processing systems - Open Systems Interconnection - Basic Reference Model - Part 3: Naming and addressing. 3 Definitions For the purposes of this Recommendation I International Standard, the following definitions apply. NOTE -The definitions contained in this clause make use of abbreviat
