1、INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU X.236 Amendment 1 (06/99) SERIES X: DATA NETWORKS AND OPEN SYSTEM COM M U N I CAT I ON S Open Systems I n tercon nect ion - Connect ion less- mode protocol specifications Information technology - Open Systems
2、 Interconnection - Connectionless Presentation protocol: Protocol specification Amendment I : Efficiency enhancements ITU-T Recommendation X.236 - Amendment 1 (Previously CCITT Recommendation) ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS PUBLIC DATA NETWORKS Services a
3、nd facilities Interfaces Transmission, signalling and switching Network aspects Maintenance Administrative arrangements OPEN SYSTEMS INTERCONNECTION Model and notation Service definitions X.l-X.19 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 Connection-mode protocol
4、 specifications X.220-X.229 Connectioness-miode protocol specifications x.230-2c.239 PICS proformas Protocol Identification Security Protocols Layer Managed Objects Conformance testing General Satellite data transmission systems MESSAGE HANDLING SYSTEMS DIRECTORY OS1 NETWORKING AND SYSTEM ASPECTS IN
5、TERWORKING BETWEEN NETWORKS Networking Efficiency Quality of service Naming, Addressing and Registration Abstract Syntax Notation One (ASN. 1) OS1 MANAGEMENT Systems Management framework and architecture Management Communication Service and Protocol X.240-X.259 X.260-X.269 X.270-X.279 X.280-X.289 X.
6、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. 649 X.650-X.679 X.680-X.699 X.700-X.709 X.710-X.719 Structure of Management Information X.720-X.729 Management functions and ODMA functions SECURITY OS1 APPLICATIONS Commitment, Concurrency and Recovery Trans
7、action processing Remote operations OPEN DISTRIBUTED PROCESSING x.730-x.799 X.800-X. 849 X.850-X.859 X.860-X.879 X.880-X.899 x.900-x.999 For further details, please refer to ITU-T List of Recommendations. INTERNATIONAL STANDARD 9576-1 ITU-T RECOMMENDATION X.236 INFORMATION TECHNOLOGY - OPEN SYSTEMS
8、INTERCONNECTION - CONNECTIONLESS PRESENTATION PROTOCOL: PROTOCOL SPECIFICATION AMENDMENT 1 Efficiency enhancements Summary Amendment 1 to ITU-T Rec. X.236 I ISO/IEC 9576-1 provides connectionless presentation protocol efficiency enhancements. Source The ITU-T Recommendation X.236, Amendment 1, was a
9、pproved on the 18th of June 1999. The identical text is also published as ISO/IEC International Standard 9576-1. _- ITU-T Rec. X.236 (1995)/Amd.l(1999 E) i FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommuni- cations. The ITU Tele
10、communication 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 Standard
11、ization Conference (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,
12、1. 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. NOTE In this Recommendation the term recognized operating agency (ROA) includes any individual, company, corporation or governmental organizati
13、on that operates 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
14、involve the use 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 t
15、his Recommendation, 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 paten
16、t database. I l O 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.236 (1995)/Arnd.l(1999 E) CONTENTS Subcla
17、use 2.1 New subclause 3.5 Subclause 4.2 Subclause 4.3 New subclause 5.5 Subclause 6.1.1 . New subclause 6.1.3 . Subclause 6.2 Subclause 6.2.1 . New subclauses 6.2.3 and 6.2.4 Clause 7 New subclause 7.2 Clause 8 Subclause 8.1.2 . New subclause 8.1.4 . Subclause 8.2 Subclause 8.3.1 . Subclause 8.3.3 .
18、 Subclause 8.4.1.3 New subclauses 8.4.2.7 and 8.4.2.8 Annex A . Page 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5 6 6 . ITU-T Rec . X.236 (1995)/Amd.l (1999 E) 111 STDmITU-T RECMN X.236 AMD I-ENGL 1779 W 4862593 Ob64633 347 ISO/IEC 9576-1 : 1999Amd.l : 1999 (E) INTERNATIONAL STANDARD ITU-T RECOMMENDATION I
19、NFORMATION TECHNOLOGY - OPEN SYSTEMS INTERCONNECTION - CONNECTIONLESS PRESENTATION PROTOCOL: PROTOCOL SPECIFICATION AMENDMENT 1 Efficiency enhancement 1) Subclause 2.1 Add the following references by numerical order: - ITU-T Recommendation X.215 (1995)/Amd. 1 (1997) I ISO/IEC 8326: 1996/Amd. 1 :1998
20、, Information technology - Open Systems Interconnection - Session Service Definition - Amendment 1: EfJiciency enhancements. - ITU-T Recommendation X.216 (1994)lAmd.l (1997) I ISO/IEC 8822:1994/Amd. 1: 1998, Information technology - Open Systems Interconnection - Presentation service dejnition - Ame
21、ndment 1 : Efficiency enhancements. - ITU-T Recommendation X.217 (1995)/Amd.2 (1997) I ISODEC 8649: 1996/Amd.2: 1998, Information technology - Open Systems Interconnection - Service definition for the Association Control Service Element (ACSE) - Amendment 2: Fast-associate mechanism. ITU-T Recommend
22、ation X.227 (1995)/Amd.2 (1997) I ISODEC 8650-1:1996/Amd.2: 1997, Information technology - Open Systems Interconnection - Connection-oriented protocol for the Association Control Service Element (ACSE): Protocol specification - Amendment 2: Fust-associate mechanism. ITU-T Recommendation X.691 (1997)
23、 I ISODEC 8825-2: 1995, Information technology -ASN. 1 encoding rules: Specijcation of Packed Encoding Rules (PER). - - 2) New subclause 3.5 Add the following new subclause afier 3.4: 3.5 Presentation protocol definitions This Recommendation I International Standard makes use of the following term d
24、efined in ITU-T Rec. X.226 I ISO/IEC 8823-1: 3.5.1 Short-encoding protocol option: An option of the presentation protocol that uses efficient encoding of a PPDU containing a single presentation data value. 3) Subclause 4.2 Add the following PPDU at the end of the list: SHORT-UD PPDU Short Unit Data
25、PPDU ITU-T Rec. X.236 (1995)/Amd.l (1999 E) 1 STDmITU-T RECNN X-236 AND L-ENGL L999 48b259L Ob64634 283 ISODEC 9576-1 : 199YAmd.l : 1999 (E) 4) Subclause 4.3 Add the following abbreviations by alphabetical order: BER Basic Encoding Rules PER Packed Encoding Rules 5) New subclause 5.5 Add ihe followi
26、ng new subclause after 5.4: 5.5 Protocol options 5.5.1 Short encoding protocol option This protocol option allows use of the Short-encoding form of User-data for any PPDU for which it is defined if the User-data contains only one presentation data value. This protocol option does not affect the Pres
27、entation service. It requires support of the Special User-data parameter of the Session primitive whose User-data is the PPDU. The use of the short encoding protocol restricts support of the Presentation service and is only available if one of the conditions a), b) or c) is applicable and condition
28、d) applies: The presentation context definition list contains precisely one item in which the abstract syntax name is known to the responding PPM by bilateral agreement. The presentation context definition list is empty and the default context is known by bilateral agreement. The presentation contex
29、t definition list is empty and the abstract syntax of the default context is specified in ASN.l and is known to the responding PPM by bilateral agreement. The calling and called presentation selectors are null. a) b) c) d) 6) Subclause 6.1.1 a) For the connectionless-mode protocol, two types of prot
30、ocol data unit, namely Unit Data PPDU (UD PPDU) and Short Unit Data PPDU (SUD PPDU), are defined. b) If the short-connect option is not selected, the PPDU transfer procedure uses the UD PPDU. If the short-connect option is selected, the PPDU transfer procedure uses the SUD PPDU. Replace the second s
31、entence with: Add the following two new paragraphs at the end of 6. I. I: 7) New subclause 6.1.3 Add the following new subclause after 6.1.2: 6.1.3 SUD PPDU associated parameters 6.1.3.1 Encoding choice. This shall indicate the transfer syntax to be used for the (single) presentation context (which
32、may be the default context) as follows: a) b) Basic Encoding Rules; c) d) transparent encoding (understood by bilateral agreement); Packed Encoding Rules (unaligned variant); Packed Encoding Rules (aligned variant). The transfer syntaxes b), c) or d) apply only if the abstract syntax is specified us
33、ing ASN. 1. 2 ITU-T Rec. X.236 (1995)/Amd.l (1999 E) STDmITU-T RECMN X.236 AMD L-ENGL 1999 = 48b2591 0664635 LLT = ISO/IEC 9576-1 : 199YAmd.l : 1999 (E) 6.1.3.2 User-data This shall be the User-data parameter for the P-UNIT-DATA request service primitive. 8) Subclause 6.2 Add the following text imme
34、diately after the subclause 6.2 heading: If the short-encoding option is not selected, the PPDU transfer procedure is described in 6.2.1 and 6.2.2. 9) Subclause 6.2.1 In the second paragraph of 6.2. I, take out the calling-session-address and the called-session-address om the list of parameters of t
35、he UD PPDU 10) New subclauses 6.2.3 and 6.2.4 Add the following wo new subclauses after 6.2.2: 6.2.3 Sending a SUD PPDU I When a P-UNIT-DATA request service primitive is received by a PPM (the initiator), and the short-encoding option is to be proposed (thus, one of the conditions a), b), or c) in 5
36、.5.1 applies and condition d) of 5.5.1 applies), the PPM may choose to transfer the user data by sending the SHORT-UNIT-DATA PPDU containing the encoding option selection parameter and user data. The calling and called address parameters of the P-UNIT-DATA request service primitive are used to deter
37、mine the calling-session-address and the called-session-address. When a P-UNIT-DATA request service primitive is received by a PPM, it shall send a SUD PPDU containing the presentation data value. A S-UNIT-DATA request service primitive is issued with the calling and called session-address parameter
38、, the Quality of Service parameter requested and the SS-user-data containing the SUD PPDU. 6.2.4 Receiving a SUD PPDU The SUD PPDU arrives in the SS-user-data field of a S-UNIT-DATA indication. The calling-session-address from the S-UNIT-DATA indication and the NIL presentation-selector will be used
39、 to determine the calling-presentation-address parameter for the P-UNIT-DATA indication. The called-session-address from the S-UNIT-DATA indication and the NIL presentation-selector will be used to determine the called-presentation-address parameter for the P-UNIT-DATA indication. If the receiving P
40、PM does not support the short-encoding protocol option and the SHORT-UNIT-DATA PPDU is received as user data on a S-UNIT-DATA indication primitive, it shall discard the PPDU without any notification. The responding PPM may refuse the proposed data transfer (if, for example, the encoding choice offer
41、ed on the SHORT-UNIT-DATA PPDU is unacceptable), in which case it shall discard the PPDU without any notification. Alternatively, if not refusing, it shall issue a P-UNIT-DATA indication service primitive. If the data transfer is accepted, the transfer syntax of the User data belonging to the (singl
42、e) presentation context (which may be the default context) is set according to the encoding-choice parameter value of the SHORT-UNIT-DATA PPDU. 11) Clause7 a) In first line of clause 7, insert subclause number and change title to: 7.1 b) Unit data transfer (long form PPDU) Replace S-CONNECT by S-UNI
43、T-DATA in item b) of 7.1. ITU-T Rec. X.236 (1995)/Amd.l (1999 E) 3 ISODEC 9576-1 : 1995/Amd.l : 1999 (E) SUD PPDU associated parameter Encoding-choice User data 12) New subclause 7.2 Add the following new subclause after 7.1: S-UNIT-DATA parameter m/nm SS-User-data m SS-User-data nm 7.2 Unit data tr
44、ansfer (short form PPDU) a) b) SUD PPDU - The SHORT-UNIT-DATA PPDU shall be conveyed from the initiating PPM to the responding PPM in the S-UNIT-DATA request and indication session-service primitives. SUD PPDU associated parameters - Table 4 defines the mapping of the SUD PPDU associated parameters
45、onto S-UNIT-DATA parameters. Table 4 - Mapping of SUD PPDU associated parameters onto S-UNIT-DATA parameters m Mandatory nm Non-mandatory 13) Clause 8 Change title of clause 8 to: 8 Structure and encoding of PPDUs 14) Subclause 8.1.2 a) The structure of SS-user data parameter values except for those
46、 in the SHORT-UNIT-DATA PPDU is specified using: b) Replace the first sentence in 8.1.2 with: Add at the end of 8.1.2: c) the specification of the short-encoding PPDUs in 8.1.4. The structure of the SHORT-UNIT-DATA PPDU is specified in 8.1.4. 15) New subclause 8.1.4 Add the following new subclause a
47、fter 8.1.3: 8.1.4 SHORT-UNIT-DATA PPDU I The protocol control information of the SHORT-UNIT-DATA PPDU shall be one octet, with the two trailing bits consisting of the encoding-choice parameter. This PCI is followed by the User-data parameter (encoded as per the encoding-choice parameter). The encodi
48、ng of the SHORT-UNIT-DATA is as shown in the following bit pattern: O000 0022 where zz identifies the encoding-choice as follows: - 00: bilateral agreement; - 01:BER; - 10: unaligned PER; - 11 : aligned PER. 4 ITU-T Rec. X.236 (1995)Amd.l (1999 E) ISOAEC 9576-1 : 1995lAmd.l : 1999 (E) 16) Subclause
49、8.2 Modifi subclause 8.2 as follows: 17) Add to UD-type, just before user-data: extensions 5 SEQUENCE . OPTIONAL, - to allow forfuture extensions In the definition of Context-list, change SEQUENCE OF to: SEQUENCE SIZE (07 ,., or b) the Packed Encoding Rules for ASN.l (ITU-T Rec. X.691 I ISOAEC 8825-2). If the responder does not support PER, the PER-encoded UD will appear to be a protocol error and the UD PPDU will be discarded without any notification. 18) Subclause 8.3.3 Replace S-CONNECT by S-UNIT-DATA. 19) Subclause 8.4.1.3 Replace item b) with the following: b
