1、INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU X.225 Amendment 2 (I 2/97) SERIES X: DATA NETWORKS AND OPEN SYSTEM COM M U N I CATI ON Open System Interconnection - Connection-mode protocol specifications Information technology - Open Systems 1 nterconnect
2、ion - Connection-oriented session protocol: Protocol specification Amendment 2: Nested connections functional unit ITU-T Recommendation X.225 - Amendment 2 (Previously CCITT Recommendation) STD.ITU-T RECMN Xe225 AMD 2-ENGL 3997 = 4862593 Ob50858 TLIi ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND
3、OPEN SYSTEM COMMUNICATION UBLIC DATA NETWORKS Services and facilities Interfaces Transmission, signalling and switching Network aspects Maintenance Administrative arrangements OPEN SYSTEM INTERCONNECTION Model and notation Service definitions Connection-mode protocol specifications Connectionless-mo
4、de protocol specifications PICS proformas Protocol Identification 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
5、of service Naming, Addressing and Registration Abstract Syntax Notation One (ASN.l) OS1 MANAGEMENT Systems Management framework and architecture Management Communication Service and Protocol Structure of Management Information Management functions and ODMA functions SECURITY OS1 APPLICATIONS Commitm
6、ent, Concurrency and Recovery Transaction processing Remote operations OPEN DISTRIBUTED PROCESSING X. 1-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 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
7、.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 X.720-X.729 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 vf Recommendations INTERNATIONAL STANDARD 8327-1 ITU-T REC
8、OMMENDATION X.225 INFORMATION TECHNOLOGY - OPEN SYSTEMS INTERCONNECTION - CONNECTION-ORIENTED SESSION PROTOCOL: PROTOCOL SPECIFICATION AMENDMENT 2 Nested connections functional unit Summary The session protocol specification defined in IT-T Rec. X.225 I ISODEC 8327-1 is enhanced to support the estab
9、lishment of additional, independent, nested session connections within an existing session connection. This enhancement will support the reusability of existing application layer standards (each making full, and possibly incompatible, use of the session synchronization services) as components of new
10、 application layer standards. Source The ITU-T Recommendation X.225, Amendment 2 was approved on the 12th of December 1997. The identical text is also published as ISO/IEC International Standard 8327-1, Amendment 2. TU-T Rec. X.225 (1995)/Amd.2 (1998 E) 1 -_ STD=ITU-T RECMN X.225 AMD 2-ENGL 1997 48b
11、2591 Ob50860 b7T D FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommuni- cations. The ITU Telecommunication Standardization Sector (IT-T) is a permanent organ of the IT. The ITU-T is responsible for studying technical, operating an
12、d tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, p
13、roduce 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 areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis
14、with IS0 and IEC. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of
15、 this Recommendation may 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
16、the date of approval of this Recommendation, the IT 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
17、to consult the TSB patent database. O ITU 1998 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. 11 ITU-T Rec. X.225 (1995)/Amd.2 (199
18、8 E) CONTENTS Subclause 2.1 . Subclause 3.2 . Subclause 5.6.10 New subclause 5.6.15 . New subclause 5.8 bis Subclause 6.1.4 New subclause 6.3.8 . Subclause 6.5 . Subclause 7.1 . Subclause 7.1.1 Subclause 7.2.1 Subclause 7.3.1 Subclause 7.4.1 Subclause 7.5.1 Subclause 7.5.2 Subclause 7.5.3 Subclause
19、7.6.1 Subclause 7.7.1 Subclause 7.7.2 Subclause 7.7.3 Subclause 7.8.1 . Subclause 7.9 . Subclause 7.9.1.1 . Subclause 7.9.1.2 . Subclause 7.9.2 Subclause 7.9.3 Subclause 7.10 . Subclause 7.1 1.1 Subclauses 7.12.1 and 7.12.2 . Subclause 7.13.1 Subclause 7.14.1 Subclause 7.15.1 Subclause 7.16.1 Subcla
20、use 7.17.1 Subclause 7.1 8.1 Subclause 7.19.1 Subclause 7.20.1 Subclause 7.21.1 Subclause 7.22.1 Page 1 1 1 1 2 2 2 3 3 3 3 3 3 3 4 4 4 4 4 5 5 5 5 5 5 6 6 6 6 7 7 7 7 7 7 7 7 8 8 . ITU-T Rec . X.225 (1995)/Amd.2 (1998 E) 111 iv STDmITU-T RECMN X-225 AND 2-ENGL 1997 4862593 O650862 442 Subclause 7.2
21、3.1 Subclause 7.24.1 Subclause 7.25.1 Subclause 7.26.1 Subclause 7.27 . Subclause 7.27.1 Subclause 7.27.2 Subclause 7.28.1 Subclause 7.29.1 Subclause 7.30.1 Subclause 7.3 1.1 Subclause 7.32.1 Subclause 7.33.1 Subclause 7.34.1 Subclause 7.35.1 Subclause 7.36.1 Subclause 8.3.1.8 . Subclause 8.3.1.16 .
22、 New subclauses 8.3.1.19 bis and 8.3.1.19 ter Subclauses 8.3.1 through 8.3.36 . Subclause A.l . Subclause C.2 . Subclause D . 1 . ITU-T Rec . X.225 (1995)/Amd.2 (1998 E) Page 8 8 8 8 8 8 8 9 9 9 9 9 9 9 9 10 10 10 10 10 11 11 11 STD.ITU-T RECMN x.225 AND 2-ENGL 1,997 m WWI, OMMH 389 m ISOIIEC 8327-1
23、 : 1996/Arnd.2 : 1998 (E) Nested connections INTERNATIONAL STANDARD No additional associated SPDUs ITU-T RECOMMENDATION INFORMATION TECHNOLOGY - OPEN SYSTEMS INTERCONNECTION - CONNECTION-ORIENTED SESSION PROTOCOL: PROTOCOL SPECIFICATION AMENDMENT 2 Nested connections functional unit 1) Subclause 2.1
24、 Insert a new reference in numerical order: - ITU-T Recommendation X.207 (1993) 1 ISOIIEC 9545:1994, Information technology - pen Systems Interconnection - Application layer structure. NOTE - ITU-T Rec. X.207 1 ISOAEC 9545 is not essential for the application of this Recommendation 1 International S
25、tandard, but is included in the list of references as it has been referred to, for information, in relation to the applicability of the nested connections functional unit. 2) Subclause 3.2 Add aper item i): j) nested session connection; k) nested session exception. 3) Subclause 5.6.10 Add to Table 3
26、 a new row just before the Notes: 4) New subclause 5.6.15 Add a new subclause as follows: 5.6.15 Nested Connections functional unit The nested connections functional unit supports the use of nested session connections. NOTE -Nested session connections enable a new Application Service Object specific
27、ation (see ITU-T Rec. X.207 I ISO/IEC 9545) to specie the inclusion within the Object of an Application Service Object governed by an existing specification. The nested session connection permits the inner Application Service Object to have full and independent access to session services (through th
28、e use of presentation services) while enabling the outer Application Service Object specification, through actions on the containing connection to retain control of synchronization, resynchronization, and aborting. The sequence of primitives issued for nested connections and for enclosing connection
29、s is preserved by the session layer. ITU-T Rec. X.225 (1995)/Amd.2 (1998 E) 1 _ STD-ITU-T RECIN X-225 AID 2-ENGL 3997 m 4862573 Ob50864 215 m ISOlIEC 8327-1 : 1996lAmd.2 : 1998 (E) 5) New subclause 5.8 bis Add a new subclause just before 5.9 as follows: 5.8 bis Nested connection identifier Each sess
30、ion connection has associated with it a nested connection identifier that is a value from O to 255 encoded as a single octet. The outermost session connection has the value zero implicitly associated. When a nested connection is initiated, the initiator of that session connection assigns a nested co
31、nnection identifier which is currently not in use for any nested connection (at any depth) on the transport connection to which the nested connection is assigned. Nested connections initiated by the initiator of the transport connection have the most significant bit of the nested connection identifi
32、er set to one. Nested connections initiated by the responder of the transport connection have the most significant bit of the nested connection identifier set to zero. The nested connection identifier is carried in all SPDUs issued as part of a nested connection. Additionally, the CONNECT SPDU carri
33、es a parent nested connection identifier that identifies the immediately enclosing session connection for the new connection. I 6) Subclause 6.1.4 Insert afier first paragraph of this subclause: When the nested connections functional unit has been negotiated for a session connection, a new nested se
34、ssion connection may be assigned to the transport connection to which the existing connection has been assigned. This assignment occurs in the initiator SPM if and only if an S-CONNECT request primitive is issued at a connection end- point nested within an existing session connection end-point. It o
35、ccurs in the responder SPM if a CONNECT SPDU is received in a transport connection on which a session connection is in progress, and results in the creation of a nested session connection end-point within the connection end-point of the parent session connection (as identified by the parent nested c
36、onnection identifier in the CONNECT SPDU) and an S-CONNECT indication primitive at the new (nested) connection end-point. Change the original fourth paragraph (beginning Only the initiator .) of this subclause: Only the initiator of a transport connection is permitted to issue the CONNECT SPDU when
37、there is no session connection on that transport connection. Where the nested connections functional unit has been agreed, both the initiator and the responder can issue the CONNECT SPDU for a nested session connection. Change the original fifth paragraph (beginning When a session connection .) of t
38、his subclause: When a session connection is terminated, all nested connections which are not yet terminated are terminated with a session provider abort. When the outermost session connection is terminated, the underlying transport connection is also terminated, unless reuse of the transport connect
39、ion has been agreed. 7) New subclause 6.3.8 Add a new subclause as follows: 6.3.8 The sequence of primitive events on a nested connection in relation to events on enclosing connections shall be preserved in the transfer of the corresponding SPDUs, and in the issue of corresponding service primitives
40、. Where the SPM of any connection enclosing a nested connection is discarding DATA SPDUs, all SPDUs on the nested connection shall be discarded, and a nested session exception occurs for the nested connection if any SPDUs are discarded for this reason. Where the SPM of any connection enclosing a nes
41、ted connection is deferring the passing of primitives (as the result of a received SPDU on the expedited path) to the service user, it shall also defer the processing of SPDUs for a nested connection which are received on the expedited path. NOTE - The service definition prevents the issue of any se
42、rvice primitives on a nested session connection unless an S-DATA primitive can be issued at that time on all enclosing session connections. It is the responsibility of enclosing application service object specifications to ensure that such states are entered in a timely manner to support the needs o
43、f any embedded application service object specification. Processing order of SPDUs on nested connections 2 ITU-T Rec. X.225 (1995)lAmd.Z (1998 E) STD.ITU-T RECMN X.225 AND 2-ENGL 1997 m Y862591 0650865 151 m ISOflEC 8327-1 : 1996/Amd.2 : 1998 (E) 8) Subclause 6.5 Add at the end of this subclause: NO
44、TE - If such flow control is exercised, it affects all session connections that are assigned to this transport connection. 9) Subclause 7.1 Change this subclause to read: The CONNECT SPDU is transmitted by the initiator of the transport connection (or in the case of a nested session connection, by e
45、ither the initiator or the responder of the transport connection) on a previously assigned transport connection in order to initiate a session connection. 10) Subclause 7.1.1 Add a sentence to the end of 7.1. I d): For nested session connections, the service primitive does not contain corresponding
46、parameters, and these parameters are absent in the protocol. Add two new items at the end of 7.1.1: g) h) For a nested session connection only, a parent nested connection identifier parameter which identifies the parent session connection. For a nested session connection only, the nested connection
47、identifier parameter assigned to this connection. 11) Subclause 7.2.1 Add at the end of this subclause: c) For a nested session connection only, the nested connection identifier parameter assigned to this connection. 12) Subclause 7.3.1 Add at the end of this subclause: c) for a nested session conne
48、ction only, the nested connection identifier parameter assigned to this connection. 13) Subclause 7.4.1 Add a sentence to the end of 7.4.1 j: For nested session connections, the service primitive does not contain corresponding parameters, and these parameters are absent in the protocol. Add a new it
49、em h) as follows: h) For a nested session connection only, the nested connection identifier parameter assigned to this connection. 14) Subclause 7.5.1 Add at the end of this subclause: g) For a nested session connection only, the nested connection identifier parameter assigned to this connection. NOTE - For a nested connection, the transport disconnect parameter shall always be set to indicate retention of the transport connection. ITU-T Rec. X.225 (1995)/Amd.2 (1998 E) 3 STDmITU-T RECMN X.225 AMD 2-ENGL 1997 D 48b2591 0b508bb 098 D ISOAEC 8327-1 : 199
