ISO/IEC 8473-1:1998 情報技術—コネクションレスモードネットワークサービスを提供するためのプロトコル：プロトコル仕様—パート1： | ページ 2

Foreword

ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work.

In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires approval by at least 75 % of the national bodies casting a vote.

International Standard ISO/IEC 8473-1 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 6, Telecommunications and information exchange between systems, in collaboration with ITU-T. The identical text is published as ITU-T Recommendation X.233.

This second edition cancels and replaces the first edition (ISO/IEC 8473-1:1994), which has been technically revised. It also incorporates Amendment 1:1995, Amendment 2:1996 and Amendment 3:1996.

ISO/IEC 8473 consists of the following parts, under the general title Information technology — Protocol for providing the connectionless-mode network service:

• Part 1: Protocol specification
• Part 2: Provision of the underlying service by an ISO/IEC 8802 subnetwork
• Part 3: Provision of the underlying service by an X.25 subnetwork
• Part 4: Provision of the underlying service by a subnetwork that provides the OSI data link service
• Part 5: Provision of the underlying service by ISDN circuit-switched B-channels
• Part 6: Provision of the underlying service assumed by ISO/IEC 8473 by subnetworks employing ISO/IEC 10028 CONS relay
• Part 7: Provision of the underlying service assumed by ISO/IEC 8473 by frame relay subnetworks

Annex A forms an integral part of this part of ISO/IEC 8473. Annexes В and С are for information only.

Introduction

This is one of a set of Recommendations and International Standards produced to facilitate the interconnection of open systems. The set covers the services and protocols required to achieve such interconnection.

This Recommendation | International Standard is positioned with respect to other related Recommendations and International Standards by the layers defined in ITU-T Rec. X.200 | ISO/IEC 7498-1. In particular, it is a protocol of the Network layer. The protocol specified by this Recommendation | 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 intermediate system. In an end system, it provides the connectionless-mode Network service defined in ITU-T Rec. X.213 | ISO/IEC 8348.

The interrelationship of the protocol specification and the related service definitions is illustrated in Figure Intro.1.

In order to evaluate the conformance of a particular implementation of this protocol, it is necessary to have a statement of which of the protocol's capabilities and options have been implemented. Such a statement is called a Protocol Implementation Conformance Statement (PICS), as defined in ITU-T Rec. X.296 | ISO/IEC 9646-7. A PICS proforma, from which a PICS may be prepared for a specific implementation, is included in this Recommendation | International Standard as normative Annex A.

1 Scope

This Recommendation | International Standard specifies a protocol that is used to provide the connectionless-mode Network service described in ITU-T Rec. X.213 | ISO/IEC 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. 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 subnetwork, as described in ISO/IEC 8648. This Recommendation | International Standard specifies the operation of the protocol with respect to a uniform, abstract"underlying subnetwork service". Other Recommendations | International Standards specify the way in which this"underlying subnetwork service" is obtained from real subnetworks, such as those which conform to ISO/IEC 8802 or ISO/IEC 8208. The"underlying subnetwork service" may be obtained from real subnetworks other than those that are specifically covered by the other Recommendations | International Standards.

This Recommendation | International Standard specifies:

• a) procedures for the connectionless transmission of data and control information from one Network entity to one or more peer Network entities;
• b) the encoding of the Protocol Data Units (PDUs) used for the transmission of data and control information, comprising a variable-length protocol header format;
• c) procedures for the correct interpretation of protocol control information; and
• d) the functional requirements for implementations claiming conformance to this Recommendation | International Standard.

The procedures are defined in terms of:

• a) the interactions among peer Network entities through the exchange of protocol data units;
• b) the interactions between a Network entity and a Network service user through the exchange of Network service primitives; and
• c) the interactions between a Network entity and an abstract underlying service provider through the exchange of service primitives.

This Recommendation | 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 | ISO/IEC 9646-1.

2 Normative references

The following Recommendations and International Standards contain provisions which, through reference in this text, constitute provisions of this Recommendation | International Standard. At the time of publication, the editions indicated were valid. All Recommendations and Standards are subject to revision, and parties to agreements based on this Recommendation | International Standard are encouraged to investigate the possibility of applying the most recent edition of the Recommendations and Standards listed below. Members of IEC and ISO maintain registers of currently valid International Standards. The Telecommunication Standardization Bureau of the ITU maintains a list of the currently valid ITU-T Recommendations.

2.1 Identical Recommendations | International Standards

2.2 Paired Recommendations | International Standards equivalent in technical content

2.3 Additional references