1、I NTERNATIONAL TELECOMMUNICATION UN ION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU X.233 (08/97) SERIES X: DATA NETWORKS AND OPEN SYSTEM COM M U N I CATI ON Open System Interconnection - Connectionless-mode protocol specifications Information technology - Protocol for providing the connec
2、tionless-mode network service: Protocol specification ITU-T Recommendation X.233 (Previously CCIT Recommendation) STD*ITU-T RECMN X-233-ENGL 1797 m LiBb257L ObLi5825 123 m ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATION PUBLIC DATA NETWORKS X. 1-X. 199 I Services and facil
3、ities Interfaces Transmission, signalling and switching Network aspects Maintenance Administrative arrangements OPEN SYSTEM INTERCONNECTION Model and notation Service definitions 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.299 X.200-X.209 x.2 10-x.2 19 Connection-m
4、ode protocol specifications X.220-X.229 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 Effici
5、ency 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 SECURITY OS1 APPLICATIONS Commitment, Concurrency and Reco
6、very Transaction processing Remote operations OPEN DISTRIBUTED PROCESSING X.240-X.259 X.260-X.269 X.270-X.279 X.280-X.289 X.290-X.299 X.300-X.399 X. 300-X.349 X.350-X.399 x.400-x.499 X.500-X.599 X.600-X.699 X. 600-X . 629 X.630-X.649 X.650-X.679 X.680-X.699 X.700-X.799 X.700-X.709 X.710-X.719 X.720-
7、X.729 x.730-x.799 X. 800-X. 849 X.850-X.899 X.850-X. 859 X.860-X.879 X.880-X.899 X.900-X.999 For further details, please refer to TU-T List of Recommendations. STD-ITU-T RECMN X-233-ENGL 1997 48b259L Ob4582b ObT = INTERNATIONAL STANDARD 8473-1 ITU-T RECOMMENDATION X.233 INFORMATION TECHNOLOGY - PROT
8、OCOL FOR PROVIDING THE CONNECTIONLESS-MODE NETWORK SERVICE: PROTOCOL SPECIFICATION Summary This Recommendation I International Standard specifies a protocol which is used to provide a connectionless-mode service as defined in the network service definition and associated management functions. The sp
9、ecification consists of the protocoi mechanisms and PDU structure for the exchange of data between end systems and intermediate systems using connectionless data transfers. The protocol defines: data transfer, error reporting and echo function. This Recommendation I International Standard includes a
10、 description of the mapping from the protocol operation onto a generalized OS1 data link service which can be used in conjunction with real subnetworks. Source The ITU-T Recommendation X.233 was approved on the 9th of August 1997. The identical text is also published as ISO/IEC International Standar
11、d 8473-1. ITU-T Rec. X.233 (1997 E) i STD-ITU-T RECMN X.233-ENGL 1977 = 48b2571 Ob45827 TTb FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommuni- cations. The IT Telecommunication Standardization Sector (ITU-T) is a permanent organ
12、 of the ITU. The ITLJ-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 Conference (WTSC), which meets every four years, establi
13、shes 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 areas of information technology which fall within ITU
14、-Ts purview, the necessary standards are prepared on a collaborative basis 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 IT
15、LJ draws attention to the possibility that the practice or implementation of 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
16、 members or others outside of the Recommendation development process. As of the date of approval of this 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 th
17、is may not represent the latest information and are therefore strongly urged to consult the TSB patent database. O IT 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, witho
18、ut permission in writing from the ITU, except as noted in footnote 1) in Annex A. ITU-T Rec. X.233 (1997 E) 11 1 2 3 CONTENTS Scope Normative references . 2.1 Identical Recommendations 1 Intemational Standards 2.2 Paired Recommendations I International Standards equivalent in technical content 2.3 A
19、dditional references Definitions 3.1 Reference model definitions . 3.2 Service conventions definitions 3.3 Network layer architecture definitions 3.4 Network layer addressing definitions . 3.5 Local area network definitions 3.6 PICS definitions 3.7 Additional definitions . 4 Abbreviations . 4.1 Data
20、 units 4.2 Protocol data units . 4.3 Protocol data unit fields 4.4 Parameters . 4.5 Miscellaneous . 5 Overview ofthe protocol . 5.1 5.2 Subsets ofthe protocol 5.3 Addresses and titles . 5.4 Service provided by the protocol 5.5 Underlying service assumed by the protocol 6 Protocol functions Internal
21、organization of the Network layer . 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 6.10 6.1 1 6.12 6.13 6.14 6.15 6.16 6.17 6.18 6.19 6.20 6.21 6.22 PDU composition function . PDU decomposition function PDU lifetime control function . Route PDU function Forward PDU function Header format analysis function . Se
22、gmentation function Reassembly function . Error reporting function Padding function . Security function . Discard PDU function . PDU header error detection function Source routeing function . Record route function . Quality of service maintenance function . Priority function Congestion notification
23、function . Echo request function . Echo response function . Scope control function Classification of functions ITU-T Rec . X.233 (1997 E) Page 1 1 1 2 2 2 2 3 3 3 3 3 3 4 4 4 4 4 4 5 5 5 5 6 6 7 7 7 8 8 8 9 9 10 10 11 12 13 13 13 14 15 15 15 15 16 17 17 . 111 STD-ITU-T RECMN X-233-ENGL 1997 D 48b257
24、L Ubi5829 877 7 Structure and encoding of PDUs 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10 7.1 1 7.12 Stnicture Fixed part Address part Segmentation part . Options part . Data part Data PDU Inactive Network layer protocol . Echo Request PDU . Multicast Data PDU Error Report PDU . Echo Response PDU . 8
25、Provision of the underlying service 8.1 8.2 Subnetwork quality of service 8.3 Subnetwork user data 8.4 Subnetwork dependent convergence functions . 9 Conformance 9.1 Static conformance 9.3 PICS proforma Annex A - PICS proforma A.l Introduction . A.2 Abbreviations and special symbols . A.3 Instructio
26、ns for completing the PICS proforma A.4 Identification . A.6 End systems A.7 Intermediate systems . Annex B - Supporting technical material B.l Data unit lifetime B.2 Reassembly lifetime control B.3 The power of the header error detection function . Annex C - Algorithms for PDU header error detectio
27、n function C.l Symbols used in algorithms C.2 Arithmetic conventions . C.3 Algorithm for generating checksum parameters . C.4 Algorithm for checking checksum parameters C.5 Subnetwork points of attachment 9.2 Dynamic conformance AS Major capabilities Algorithm to adjust the checksum parameter when a
28、n octet is altered . Page 18 18 19 21 22 23 29 29 30 30 32 33 33 33 33 33 34 35 35 35 37 37 38 38 38 38 40 41 41 47 52 52 53 54 56 56 56 56 56 57 iv ITU-T Rec . X.233 (1997 E) Introduction This is one of a set of Recommendations and International Standards produced to facilitate the interconnection
29、of open systems. The set covers the services and protocols required to achieve such interconnection. This Recommendation I Intemational Standard is positioned with respect to other related Recommendations and Intemational Standards by the layers defined in ITU-T Rec. X.200 I ISO/IEC 7498-1. In parti
30、cular, it is a protocol of the Network layer. The protocol specified by this Recommendation I International Standard may be used between Network entities in end systems, between Network entities in intermediate systems, or between a Network entity in an end system and a Network entity in an intermed
31、iate system. In an end system, it provides the connectionless-mode Network service defined in ITU-T Rec. X.213 I ISO/IEC 8348. The interrelationship of the protocol specification and the related service definitions is illustrated in Figure Intro. 1. OS1 Network service Protocol Reference to aims T s
32、pecification Reference to assumptions Underlying service I TO71 8880-93/d01 Figure Intro. 1 - Interrelationship of protocol and services In order to evaluate the conformance of a particular implementation of this protocol, it is necessary to have a statement of which of the protocols capabilities an
33、d options have been implemented. Such a statement is called a Protocol Implementation Conformance Statement (PICS), as defined in IT-T Rec. X.296 I ISO/IEC 9646-7. A PICS proforma, from which a PICS may be prepared for a specific implementation, is included in this Recommendation I International Sta
34、ndard as normative Annex A. ITU-T Rec. X.233 (1997 E) V ISODEC 8473-1 : 1998 (E) INTERNATIONAL STANDARD ITU-T RECOMMENDATION INFORMATION TECHNOLOGY - PROTOCOL FOR PROVIDING THE CONNECTIONLESS-MODE NETWORK SERVICE: PROTOCOL SPECIFICATION 1 Scope This Recommendation I International Standard specifies
35、a protocol that is used to provide the connectionless-mode Network service described in ITU-T Rec. X.213 I ISOAEC 8348 and to perform certain Network layer management functions. The protocol relies upon the provision of an underlying connectionless-mode service by real subnetworks and/or data links.
36、 The underlying connectionless-mode service assumed by the protocol may be obtained either directly, from a connectionless-mode real subnetwork, or indirectly, through the operation of an appropriate Subnetwork Dependent Convergence Function (SNDCF) or Protocol (SNDCP) over a connection-mode real su
37、bnetwork, as described in ISODEC 8648. This Recommendation I International Standard specifies the operation of the protocol with respect to a uniform, abstract “underlying subnetwork service”. Other Recommendations I International Standards specifj the way in which this “underlying subnetwork servic
38、e” is obtained from real subnetworks, such as those which conform to ISOAEC 8802 or ISOiEC 8208. The “underlying subnetwork service” may be obtained from real subnetworks other than those that are specifically covered by the other Recommendations I Intemational Standards. This Recommendation I Inter
39、national Standard specifies: a) b) c) d) procedures for the connectionless transmission of data and control information from one Network entity to one or more peer Network entities; the encoding of the Protocol Data Units (PDUs) used for the transmission of data and control information, comprising a
40、 variable-length protocol header format; procedures for the correct interpretation of protocol control information; and the functional requirements for implementations claiming conformance to this Recommendation 1 international Standard. The procedures are defined in terms of: a) b) c) the interacti
41、ons among peer Network entities through the exchange of protocol data units; the interactions between a Network entity and a Network service user through the exchange of Network service primitives; and the interactions between a Network entity and an abstract underlying service provider through the
42、exchange of service primitives. This Recommendation I International Standard also provides the PICS proforma for this protocol, in compliance with the relevant requirements, and in accordance with the relevant guidance, given in ITU-T Rec. X.290 I ISOAEC 9646-1. 2 Normative refer en ces The followin
43、g Recommendations and International Standards contain provisions which, through reference in this text, constitute provisions of this Recommendation 1 International Standard. At the time of publication, the editions indicated were valid. All Recommendations and Standards are subject to revision, and
44、 parties to agreements based on this Recommendation I Intemational Standard are encouraged to investigate the possibility of applying the most recent edition of the Recommendations and Standards listed below. Members of IEC and IS0 maintain registers of currently valid International Standards. The T
45、elecommunication Standardization Bureau of the IT maintains a list of the currently valid ITU-T Recommendations. 2.1 Identical Recommendations I International Standards - ITU-T Recommendation X.200 (1994) I ISO/IEC 7498-1:1994, Infirmation technology - Open Systems Interconnection - Reference Model:
46、 The Basic Model. 1 ITU-T Rec. X.233 (1997 E) Previous page is blank STD-ITU-T RECMN X-233-ENGL 1777 E LiBb259L 0b4.5832 3b3 ISO/IEC 8473-1 : 1998 (E) - ITLJ-T Recommendation X.210 (1993) I ISOAEC 1073 1: 1994, Information technology - Open Systems Interconnection - Basic Reference Model: Convention
47、s for the definition of OSI services. IT-T Recommendation X.213 (1995) I ISOAEC 8348:1996, Information technology - Open Systems Interconnection -Network service dejnition. IT-T Recommendation X.224 (1995) I ISOAEC 8073:1997, Information technology - Open Systems Interconnection - Protocol for provi
48、ding the connection-mode transport service. - - 2.2 Paired Recommendations I International Standards equivalent in technical content - ITU-T Recommendation X.290 (1995), OSI conformance testing methodology and pamework for protocol Recommendations for ITU-T applications - General concepts. ISODEC 96
49、46- 1 : 1994, Information technology - Open Systems Interconnection - Conformance testing methodology andpamework - Part 1: General concepts. ITU-T Recommendation X.296 (1999, OSI conformance testing methodology and framework for protocol Recommendations for ITU-T applications - Implementation conformance statements. ISOAEC 9646-7: 1995, Information technology - Open Systems Interconnection - Conformance testing methodology andflamework - Part 7: Implementation Conformance Statements. - 2.3 Additional references - ITU-T Recommendation
