1、INTERNATIONAL TELECOMMUNICATION UNION lTU=T TELECOMMUNICATION STAN DARD IZATION SECTOR OF ITU X.235 Amendment I (06/99) SERIES X: DATA NETWORKS AND OPEN SYSTEM COM M U N I CATI ON S Open Systems Interconnection - Connectionless-mode protocol specifications Information technology - Open Systems Inter
2、connection - Connectionless Session protocol: Protocol specification Amendment I : Efficiency enhancements ITU-T Recommendation X.235 - Amendment 1 (Previously CCITT Recommendation) ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS PUBLIC DATA NETWORKS Services and faciliti
3、es Interfaces Transmission, signalling and switching Network aspects Maintenance Administrative arrangements OPEN SYSTEMS INTERCONNECTION Model and notation Service definitions Connection-mode protocol specifications Connectionless-mode protocol specifications PICS proformas Protocol Identification
4、Security Protocols Layer Managed Objects Conformance testing INTERWORKING BETWEEN NETWORKS General Satellite data transmission systems MESSAGE HANDLING SYSTEMS DIRECTORY OS1 NETWORKING AND SYSTEM ASPECTS Networking Efficiency Quality of service Naming, Addressing and Registration Abstract Syntax Not
5、ation One (ASN.1) OS1 MANAGEMENT Systems Management framework and architecture Management Communication Service and Protocol Structure of Management Information Management functions and ODMA functions SECURITY OS1 APPLICATIONS Commitment, Concurrency and Recovery Transaction processing Remote operat
6、ions OPEN DISTRIBUTED PROCESSING X. 1 -X. 1 9 X.20-X.49 X.50-X.89 X.90-X. 149 X. 150-X. 179 X. 180-X. 199 X.200-X.209 X.210-X.219 X.220-X.229 X.230-X.239 X.240-X.259 X.260-X.269 X.270-X.279 X.280-X.289 X.290-X.299 X.300-X.349 X. 350-X. 399 X.400-X.499 X.500-X.599 X.600-X.629 X.630-X.639 X. 640-X. 64
7、9 X.650-X.679 X.680-X.699 X.700-X.709 X.710-X.719 X.720-X.729 X.736X.799 X. 800-X.849 X.850-X.859 X.866X.879 X. 880-X. 899 X.900-X.999 For further details, please refer to ITU-T List OfRecommendations. INTERNATIONAL STANDARD 9548-1 ITU-T RECOMMENDATION X.235 INFORMATION TECHNOLOGY - OPEN SYSTEMS INT
8、ERCONNECTION - CONNECTIONLESS SESSION PROTOCOL: PROTOCOL SPECIFICATION AMENDMENT 1 Efficiency enhancements Summary Amendment 1 to ITU-T Rec. X.235 I ISO/iEC 9548- 1 provides connectionless session protocol efficiency enhancements. Source The ITU-T Recommendation X.235, Amendment 1, was approved on t
9、he 18th of June 1999. The identical text is also published as ISOAEC International Standard 9548-1. ITU-T Rec. X.235 (1995)/Amd.l (1999 E) 1 - FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommuni- cations. The ITU Telecommunication
10、 Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Confe
11、rence (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. In some ar
12、eas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation the term recognized operating agency (ROA) includes any individual, company, corporation or governmental organization that opera
13、tes a public correspondence service. The terms Administration, ROA and public correspondence are defined in the Constitution of the ITU (Geneva, 1992). INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the u
14、se of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommend
15、ation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. O
16、 ITU 1999 All rights reserved. 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 the ITU. II ITU-T Rec. X.235 (1995)/Amd.l (1999 E) CONTENTS Page Introduction iv 1
17、Subclause 3.2 1 Subclause 4.2 1 Subclause 4.3 . 1 Subclause 6.1.3 . 1 Subclause 6.2.3 . 2 Subclause 6.2.4 . 2 New subclauses 6.2.6 and 6.2.7 2 Clause 7 2 Subclause 7.2 3 Subclauses 7.2.1 through 7.2.5 . . 3 Subclause 7.3 3 New subclauses 7.4 and 7.5 3 Annex A . . 5 ITU-T Rec. X.235 (1995)/Amd.l (199
18、9 E) - . 111 STD=ITU-T RECMN X-235 AflD II-ENGL 1999 W 48b259L Obb4b2L b25 Introduction This amendment is one of a set of amendments to the OS1 upper-layers standards produced to facilitate the interconnection of information processing systems in an open environment where efficiency of communication
19、s is paramount. Such efficiencies include: a) reduction in the overhead needed to encode control information for use in bandwidth-limited environments (such as radio links) or processing-limited systems (such as switching systems); b) reduction in the delay to set up the association between the comm
20、unicating applications so that data transfer can begin expeditiously; c) reduction in the support of unneeded functionality in certain environments where the communications requirements of the applications are limited. This amendment modifies the connectionless Session Protocol to support the “short
21、-encoding“ protocol option. The short-encoding option provides alternative and smaller protocol control information for the connectionless-mode session protocol data units. Previous page is blank ITU-T Rec. X.235 (1995)/Amd.l (1999 E) V - STDmITU-T RECMN X-235 AND II-ENGL 1997 4862591 Ohh4b22 SbL IS
22、O/IEC 9548-1 : 1996lAmd.l : 1999 (E) INTERNATIONAL STANDARD ITU-T RECOMMENDATION INFORMATION TECHNOLOGY - OPEN SYSTEMS INTERCONNECTION - CONNECTIONLESS SESSION PROTOCOL: PROTOCOL SPECIFICATION AMENDMENT 1 Efficiency enhancements 1) Subclause 2.1 Add the following reference by numerical order: - ITU-
23、T Recommendation X.2 I5 (1 995)/Amd. 1 (1997) I ISOAEC 8326: 1996/Amd. 1 : 1998, Information technology - Open Systems Interconnection - Session Service Definition - Amendment 1: Efficiency enhancements. 2) Subclause 3.2 Add the following definitions after 3.2.2: 3.2.3 3.2.4 names that begin with th
24、e word SHORT and abbreviations beginning with the letter S. 3.2.5 control information of the Session SPDUs in the data transfer phase. 3.2.6 will contain the SPDU identifier). Long-form SPDU: An SPDU that has the long-form structure defined in 7.2. Short-form SPDU: An SPDU that has the short-form st
25、ructure defined in 7.4. All short-form SPDUs have Short-encoding protocol option: An option of the session protocol that permits the use of smaller protocol Parameter indication: A field in the low-order bits of the first octet of a short-form SPDU (the high-order bits 3) Subclause 4.2 Add the follo
26、wing abbreviation by alphabetical order: SUD SPDU Short Unit Data SPDU 4) Subclause 4.3 Add the following abbreviation by alphabetical order: SI zero, one or more parameter fields defined for the short-form SPDU; a) b) c) either: i) one unspecified-length parameter, if defined for the SPDU; or i) th
27、e User-information field, if defined for the SPDU and if present. ITU-T Rec. X.235 (1995)/Amd.l (1999 E) 3 STD-ITU-T RECMN X.235 AMD 3-ENGL 1999 4862593 Obb4b25 270 ISO/IEC 9548-1 : 199WAmd.l : 1999 (E) The SI the high- order bit (bit 8 of the SI bit 3 = 1 : at least octet 2 contains an SPDU paramet
28、er. If there are no following octets, bit 3 shall be zero. It is specified for each short-form SPDU, if octet 2 contains an SPDU parameter, how many of the following octets contain parameters and which of the following octets, if any, contain User-information. 7.4.3 Special data For some short-form
29、SPDUs bits 1 and 2 of the SI The value shown in position W represents bit 7 of the SI The value shown in position X represents bit 6 of the SI 4 ITU-T Rec. X.235 (1995)/Amd.l (1999 E) STD-ITU-T RECMN X-235 AMD L-ENGL L999 48b259L Obb4b2b LO? m ISO/IEC 9548-1 : 199dAmd.l : 1999 (E) UD SUD - - The val
30、ue shown in position Y represents bit 5 of the SI The value shown in position Z represents bit 4 of the SI sent as TS-user-data on a T-UNIT-DATA request primitive Short-form Session Unit Data SPDU ; sent as TS-user-data on a T-UNIT-DATA request primitive SUD 4 Add the following row in Table A.2, Out
31、going events for the SUD outgoing event, and change, as shown by the underlined text, the descripiion of the UD outgoing event: S-UNIT-DATAind Idle 4 Add the following entry to Table A.3, Unit Data Transfer State Table for SUD event, und change, us shown by the underlying text, the description of S-
32、UNIT-DATAreq. State Event S-UNIT-D ATAreq Idle !l! SUD leL UD Idle ITU-T Rec. X.235 (1995)/Amd.l (1999 E) 5 STD-ITU-T RECMN X.235 AND 3-ENGL 3777 4862573 Obb4b27 043 = Series A Series B Series C Series D Series E Series F Series G Series H Series I Series J Series K Series L Series M Series N Series
33、 O Series P Series Q Series R Series S Series T Series U Series V Series X Series Y Series Z ITU-T RECOMMENDATIONS SERIES Organization of the work of the ITU-T Means of expression: definitions, symbols? classification General telecommunication statistics General tariff principles Overall network ope
34、ration, telephone service, service operation and human factors Non-telephone telecommunication services Transmission systems and media, digital systems and networks Audiovisual and multimedia systems Integrated services digital network Transmission of television, sound programme and other multimedia
35、 signals Protection against interference Construction, installation and protection of cables and other elements of outside plant TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits Maintenance: international sound programme a
36、nd television transmission circuits Specifications of measuring equipment Telephone transmission quality, telephone installations, local line networks Switching and signalling Telegraph transmission Telegraph services terminal equipment Terminals for telematic services Telegraph switching Data communication over the telephone network Data networks and open system communications Global information infrastructure Languages and general software aspects for telecommunication systems Printed in Switzerland Geneva, 1999
