Internet Engineering Task Force (IETF)                        B. Lengyel
Request for Comments: 9195                                      Ericsson
Category: Standards Track                                      B. Claise
ISSN: 2070-1721                                                   Huawei
                                                           February 2022

A File Format for YANG Instance Data




There is a need to document data defined in YANG models at design time, implementation time, or when a live server is unavailable. This document specifies a standard file format for YANG instance data, which follows the syntax and semantics of existing YANG models and annotates it with metadata.


Status of This Memo


This is an Internet Standards Track document.


This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.

この文書はインターネットエンジニアリングタスクフォース(IETF)の製品です。IETFコミュニティのコンセンサスを表します。それはパブリックレビューを受け、インターネットエンジニアリングステアリンググループ(IESG)による出版の承認を受けました。インターネット規格に関する詳細情報は、RFC 7841のセクション2で利用できます。

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at


Copyright Notice


Copyright (c) 2022 IETF Trust and the persons identified as the document authors. All rights reserved.

著作権(c)2022 IETF信頼と文書の著者として識別された人。全著作権所有。

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents ( in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.

この文書は、この文書の公開日に有効なIETF文書(に関するBCP 78およびIETF信頼の法的規定の対象となります。この文書に関してあなたの権利と制限を説明するので、これらの文書をよくレビューしてください。この文書から抽出されたコードコンポーネントには、信託法定規定のセクション4。

Table of Contents


   1.  Introduction
     1.1.  Terminology
     1.2.  Principles
     1.3.  Delivery of Instance Data
     1.4.  Data Life Cycle
   2.  Instance Data File Format
     2.1.  Specifying the Content Schema
       2.1.1.  Inline Method
       2.1.2.  Simplified-Inline Method
       2.1.3.  URI Method
     2.2.  Examples
       2.2.1.  Documentation of Server Capabilities
       2.2.2.  Preloading Default Configuration Data
       2.2.3.  Storing Diagnostics Data
   3.  YANG Instance Data Model
     3.1.  Tree Diagram
     3.2.  YANG Model
   4.  Security Considerations
   5.  IANA Considerations
     5.1.  URI Registration
     5.2.  YANG Module Name Registration
   6.  References
     6.1.  Normative References
     6.2.  Informative References
   Appendix A.  Backwards Compatibility
   Appendix B.  Detailed Use Cases
     B.1.  Use Case 1: Early Documentation of Server Capabilities
     B.2.  Use Case 2: Preloading Data
     B.3.  Use Case 3: Documenting Factory Default Settings
   Authors' Addresses
1. Introduction
1. はじめに

There is a need to document data defined in YANG models when a live server is unavailable. Data is often needed at design time, implementation time, or even later when a live running server is unavailable. To facilitate this offline delivery of data, this document specifies a standard format for YANG instance data sets and YANG instance data files. The format of the instance data set is defined by the "ietf-yang-instance-data" YANG module; see Section 3. The YANG data model in this document conforms to the Network Management Datastore Architecture (NMDA) defined in [RFC8342].


The following is a list of already-implemented and potential use cases.


UC1 Documentation of server capabilities


UC2 Preloading default configuration data


UC3 Documenting factory default settings


UC4 Storing the configuration of a device, e.g., for backup, archive, or audit purposes


UC5 Storing diagnostics data


UC6 Allowing YANG instance data to potentially be carried within other inter-process communication (IPC) message formats


UC7 Default instance data used as part of a templating solution


UC8 Providing data examples in RFCs or internet drafts

UC8 RFCまたはインターネットドラフトでデータ例を提供します

Appendix B describes the first three use cases in detail.


There are many and varied use cases where YANG instance data could be used. This document does not limit future uses of instance data sets, so specifying how and when to use YANG instance data is out of scope for this document. It is anticipated that other documents will define specific use cases. Use cases are listed only as examples.


1.1. Terminology
1.1. 用語

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

この文書のキーワード "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", および "OPTIONAL" はBCP 14 [RFC2119] [RFC8174]で説明されているように、すべて大文字の場合にのみ解釈されます。

Instance Data: A collection of instantiated data nodes.


Instance Data Set: A named set of data items annotated with metadata that can be used as instance data in a YANG data tree.


Instance Data File: A file containing an instance data set formatted according to the rules described in this document.


Content-schema: A set of YANG modules with their revision, supported features, and deviations for which the instance data set contains instance data.


Content-defining YANG Module: An individual YANG module that is part of the content-schema.


The term "server" is used as defined in [RFC8342].


1.2. Principles
1.2. 原則

The following is a list of the basic principles of the instance data format:


P1 Two standard formats shall be defined based on the XML and JSON encodings.

P1 2つの標準フォーマットは、XMLおよびJSONエンコーディングに基づいて定義されます。

P2 Instance data shall reuse existing encoding rules for YANG-defined data.


P3 Metadata about the instance data set (Section 2, Paragraph 14) shall be defined.


P4 A YANG instance data set shall be allowed to contain data for multiple YANG modules.

P4 Yangインスタンスデータセットには、複数のYANGモジュールのデータを含めることができます。

P5 Instance data shall be allowed to contain configuration data, state data, or a mix of the two.


P6 Partial data sets shall be allowed.


P7 The YANG instance data format shall be usable for any data for which YANG module(s) are defined and available to the reader, independent of whether the module is implemented by a server.

P7 Yangインスタンスデータフォーマットは、モジュールがサーバによって実装されているかどうかとは無関係に、Yangモジュールが定義され、読者が利用できるデータに対して使用可能でなければならない。

P8 It shall be possible to report the identity of the datastore with which the instance data set is associated.


1.3. Delivery of Instance Data
1.3. インスタンスデータの配信

Instance data sets that are produced as a result of some sort of specification or design effort may be available without the need for a live server, e.g., via download from the vendor's website or in any other way that product documentation is distributed.


Other instance data sets may be read from or produced by the YANG server itself, e.g., UC5 documenting diagnostic data.


1.4. Data Life Cycle
1.4. データライフサイクル

A YANG instance data set is created at a specific point of time. If the data changes afterwards, the instance data set will no longer represent the current data unless it is updated. The current values may be retrieved at runtime via NETCONF/RESTCONF or received, e.g., in YANG-Push notifications.

Yangインスタンスデータセットは特定の時点で作成されます。データが後で変更された場合、インスタンスデータセットは更新されない限り、現在のデータを表しなくなります。現在の値は、NETCONF / RETCONFを介して実行時に検索されてもよく、または受信された、例えばYang-Push通知で受信されてもよい。

Whether the instance data changes and, if so, when and how should be described either in the instance data set's description statement or in some other implementation-specific manner.


2. Instance Data File Format
2. インスタンスデータファイルの形式

A YANG instance data file MUST contain a single instance data set and no additional data.


The format of the instance data set is defined by the "ietf-yang-instance-data" YANG module. It is made up of a header part and content-data. The header part carries metadata for the instance data set. The content-data, defined as an anydata data node, carries the instance data that the user wants to document and/or provide. The syntax and semantics of content-data are defined by the content-schema.


Two formats are specified based on the XML and JSON YANG encodings. The file formats are achieved by applying the respective XML and JSON encoding rules for the YANG structure included in this document. Later, as other YANG encodings (e.g., CBOR) are defined, further instance data formats may be specified.

XMLおよびJSON YANGエンコーディングに基づいて2つのフォーマットが指定されています。このドキュメントに含まれているYANG構造のそれぞれのXMLおよびJSONエンコード規則を適用することによって、ファイル形式が実現されます。その後、他のYAN符号化(例えば、CBOR)が定義されているので、さらなるインスタンスデータフォーマットを指定することができる。

The content-data part MUST conform to the content-schema while allowing for the exceptions listed below. The content-data part SHALL follow the encoding rules defined in [RFC7950] for XML and [RFC7951] for JSON and MUST use UTF-8 character encoding. Content-data MAY include:

Content-Data Partは、以下にリストされている例外を可能にしながら、Content-Schemaに準拠している必要があります。コンテンツデータ部は、XMLの[RFC7950]で定義されている符号化規則に従っており、JSON用の[RFC7951]に従わなければならず、UTF-8文字エンコーディングを使用する必要があります。コンテンツデータは次のとおりです。

* metadata, as defined by [RFC7952].

* [RFC7952]で定義されているメタデータ。

* origin metadata, as specified in [RFC8526] and [RFC8527].

* [RFC8526]と[RFC8527]で指定されている原点メタデータ。

* implementation-specific metadata relevant to individual data nodes. Unknown metadata MUST be ignored by users of instance data, allowing it to be used later for other purposes.

* 個々のデータノードに関連する実装固有のメタデータ。不明なメタデータはインスタンスデータのユーザーによって無視されなければならず、後で他の目的のために使用されることを可能にします。

An instance data set MAY contain data for any number of YANG modules; if needed, it MAY carry the complete configuration and state data for a server. Default values should be excluded where they do not provide additional useful data.


Configuration ("config true") and operational state data ("config false") MAY be mixed in the instance data file.

インスタンスデータファイルで設定( "config true")と動作状態データ( "config false")を混在させることができます。

Instance data files MAY contain partial data sets. This means "mandatory", "min-elements", "require-instance true", "must", and "when" constraints MAY be violated.

インスタンスデータファイルには部分データセットを含めることができます。これは「必須」、「最小要素」、「必須 - インスタンスTRUE」、「必須」、および「必須」、および「必ず」制約が違反することを意味します。

The name of the instance data file SHOULD be of the following form (using ABNF notation [RFC5234]):


      instance-data-set-name ["@" ( revision-date / timestamp ) ]
                     ( ".xml" / ".json" )

Examples include:


acme-router-modules.xml acme-router-modules@2018-01-25.xml acme-router-modules@2018-01-25T15_06_34_3+01_00.json

acme-router-modules.xml acme-router-modules@2018-01-25.xml acme-router-modules @ 2018-01-25T15_06_34_3 01_00.json

If the leaf "name" is present in the instance data header, its value SHOULD be used for the "instance-data-set-name" in the filename. If the "revision-date" is present in the filename, it MUST conform to the format of the revision-date leaf in the YANG model. If the "revision-date" is present in both the filename and the instance data header, the revision date in the filename MUST be set to the latest revision date inside the instance data set. If the "timestamp" is present in the filename, it MUST conform to the format of the timestamp leaf in the YANG model except for replacing colons as described below. If the "timestamp" is present in both the filename and the instance data header, the timestamp in the filename SHOULD be set to the timestamp inside the instance data set; any colons, if present, shall be replaced by underscores.

leaf "name"がインスタンスデータヘッダーに存在する場合、その値はファイル名の "instance-data-set-name"に使用する必要があります。「Revision-Date」がファイル名に存在する場合は、YANDモデルのリビジョンデートリーフのフォーマットに準拠している必要があります。ファイル名とインスタンスデータヘッダーの両方に "Revision-Date"が存在する場合は、ファイル名のリビジョン日をインスタンスデータセット内の最新のリビジョン日に設定する必要があります。「タイムスタンプ」がファイル名に存在する場合、以下のようなコロンを置き換えることを除いて、YANDモデル内のタイムスタンプリーフのフォーマットに準拠しなければなりません。ファイル名とインスタンスデータヘッダの両方に「timestamp」が存在する場合、ファイル名のタイムスタンプはインスタンスデータセット内のタイムスタンプに設定する必要があります。存在する場合は、どんなコロンもアンダースコアに置き換えなければならない。

Metadata, information about the data set itself, MUST be included. Some metadata items are defined in the YANG module "ietf-yang-instance-data", but other items MAY be used.

メタデータ、データセット自体に関する情報を含める必要があります。いくつかのメタデータ項目は、Yangモジュール "IETF-YANG-INSUMPON-INSUMENT"で定義されていますが、他の項目を使用することもできます。

Metadata MUST include:


- Version of the YANG instance data format (if not explicitly present, the default value is used).

- Yangインスタンスデータ形式のバージョン(明示的に存在しない場合は、デフォルト値が使用されます)。

Metadata SHOULD include:


- Name of the data set.

- データセットの名前。

- Content-schema specification (i.e., the "content-schema" node).

- Content-Schema指定(すなわち、「コンテンツスキーマ」ノード)。

- Description of the instance data set. The description SHOULD contain information on whether and how the data can change during the lifetime of the server.

- インスタンスデータセットの説明。説明には、サーバーの有効期間中にデータがどのように変更できるかどうかについての情報を含める必要があります。

- An indication of whether default values are included. The default handling uses the concepts defined in [RFC6243]; however, as only concepts are re-used, users of instance data sets do not need to support [RFC6243].

- デフォルト値が含まれているかどうかの表示。デフォルトの処理は[RFC6243]で定義されている概念を使用します。ただし、概念のみが再使用されると、インスタンスデータセットのユーザーは[RFC6243]をサポートする必要はありません。

2.1. Specifying the Content Schema
2.1. コンテンツスキーマを指定します

To properly understand and use an instance data set, the user needs to know the content-schema. The content-schema can be specified either in external documents or within the instance data set. In the latter case, one of the following methods MUST be used:


Inline method: Include the needed information as part of the instance data set.


Simplified-inline method: Include the needed information as part of the instance data set; only the modules' name and revision-date are used.


URI method: Include a URI that references another YANG instance data file. This instance data file will use the same content-schema as the referenced YANG instance data file (if you don't want to repeat the info again and again).


Additional methods, e.g., a YANG-package-based solution may be added later.


Note that the specified content-schema only indicates the set of modules that were used to define this YANG instance data set. Sometimes instance data may be used for a server supporting a different YANG module set (e.g., for the "Preloading default configuration data" use case, UC2 in Section 1, the instance data set may not be updated every time the YANG modules on the server are updated). Whether an instance data set originally defined using a specific content-schema is usable with another schema depends on many factors, including the number of differences and the compatibility between the original and the other schema when considering modules, revisions, features, deviations, the scope of the instance data, etc.


2.1.1. Inline Method
2.1.1. インラインメソッド

The "inline-yang-library" anydata data node carries instance data (conforming to "ietf-yang-library@2019-01-04") [RFC8525] that specifies the content-defining YANG modules, including revision, supported features, deviations, and any additional relevant data. An example of the inline method is provided in Section 2.2.1.

"Inline-Yang-Library" anydataデータノードはインスタンスデータ( "Ietf-Yang-Library @ 2019-01-04"に準拠しています(RFC8525]は、リビジョン、サポート機能、偏差など、コンテンツ定義YANGモジュールを指定します。、追加の関連データ。インラインメソッドの例をセクション2.2.1に提供しています。

2.1.2. Simplified-Inline Method
2.1.2. 簡略化インラインメソッド

The instance data set contains a list of content-defining YANG modules, including the revision date for each. Usage of this method implies that the modules are used without any deviations and with all features supported. YANG modules that are only required to satisfy import-only dependencies MAY be excluded from the leaf-list. If they are excluded, then the consumer of the instance data set has to apply the YANG language rules to resolve the imports. An example of the simplified-inline method is provided in Section 2.2.2.


2.1.3. URI Method
2.1.3. URIメソッド

The "same-schema-as-file" leaf SHALL contain a URI that references another YANG instance data file. The current instance data file will use the same content-schema as the referenced file.


The referenced instance data file MAY have no content-data if it is used solely for specifying the content-schema.


If a referenced instance data file is unavailable, the content-schema is unknown.


The URI method is advantageous when the user wants to avoid the overhead of specifying the content-schema in each instance data file -- for example, in UC6, when the system creates a diagnostic file every minute to document the state of the server.


An example of the URI method is provided in Section 2.2.3.


2.2. Examples
2.2. 併せた
2.2.1. Documentation of Server Capabilities
2.2.1. サーバー機能のドキュメント

The example file acme-router-modules@2022-01-20.xml reflects UC1 in Section 1. It provides a list of supported YANG modules and NETCONF capabilities for a server. It uses the inline method to specify the content-schema.


The example uses artwork folding [RFC8792].


   ========== NOTE: '\' line wrapping per RFC 8792 ===========
   <?xml version="1.0" encoding="UTF-8"?>
   <instance-data-set xmlns=\
         <modules-state \
       <description>Initial version</description>
     <description>Defines the minimal set of modules that any \
         acme-router will contain. This minimal set will \
         only change when a new software release is \
       <modules-state \
       <netconf-state \

Figure 1


2.2.2. Preloading Default Configuration Data
2.2.2. デフォルト設定データをプリロードする

The example file read-only-acm-rules@2022-01-20.xml reflects UC2 in Section 1. It provides a default rule set for a read-only operator role. It uses the simplified-inline method for specifying the content-schema.

例ファイルread-only-acm-rules @ 2022-01-20.xmlは、セクション1のUC2を反映しています。読み取り専用の演算子の役割のデフォルトのルールセットを提供します。Content-Schemaを指定するための単純化されたインライン方法を使用します。

   ========== NOTE: '\' line wrapping per RFC 8792 ===========
   <?xml version="1.0" encoding="UTF-8"?>
       <description>Initial version</description>
     <description>Default access control rules for a read-only \
         role. This set of rules will only change when a new  \
         software release is introduced.</description>
       <nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm">

Figure 2


2.2.3. Storing Diagnostics Data
2.2.3. 診断データを保存する

The example file acme-router-netconf-diagnostics@2018-01-25T17_00_38Z.json reflects UC5 in Section 1. An instance data set that contains statistics about the NETCONF server is produced by the server every 15 minutes. As a new set is produced periodically many times a day, a revision-date would be useless; instead, a timestamp is included.


   ========== NOTE: '\' line wrapping per RFC 8792 ===========
     "ietf-yang-instance-data:instance-data-set": {
       "name": "acme-router-netconf-diagnostics",
       "content-schema": {
         "same-schema-as-file": "file:///acme-diagnostics-schema.json"
       "timestamp": "2018-01-25T17:00:38Z",
       "description":  ["NETCONF statistics, \
           The data may change at any time."],
       "content-data": {
         "ietf-netconf-monitoring:netconf-state": {
           "statistics": {
             "netconf-start-time ": "2018-12-05T17:45:00Z",
             "in-bad-hellos ": "32",
             "in-sessions ": "397",
             "dropped-sessions ": "87",
             "in-rpcs ": "8711",
             "in-bad-rpcs ": "408",
             "out-rpc-errors ": "408",
             "out-notifications": "39007"

Figure 3


3. YANG Instance Data Model
3. Yangインスタンスデータモデル
3.1. Tree Diagram
3.1. 樹形図

The following tree diagram [RFC8340] provides an overview of the data model.


   module: ietf-yang-instance-data
     structure instance-data-set:
       +--name?                string
       +--format-version?      string
       +--includes-defaults?   enumeration
       |  +--(content-schema-spec)?
       |     +--:(simplified-inline)
       |     |  +--module*                module-with-revision-date
       |     +--:(inline)
       |     |  +--inline-yang-library    <anydata>
       |     +--:(uri)
       |        +--same-schema-as-file?   inet:uri
       +--description*         string
       +--contact?             string
       +--organization?        string
       +--datastore?           ds:datastore-ref
       +--revision* [date]
       |  +--date           string
       |  +--description?   string
       +--timestamp?           yang:date-and-time
       +--content-data?        <anydata>
3.2. YANG Model
3.2. ヤンのモデル

This YANG module imports typedefs from [RFC6991], [RFC6243], identities from [RFC8342], and the "structure" extension from [RFC8791]. It also references [RFC8525].


   <CODE BEGINS> file "ietf-yang-instance-data@2022-02-17.yang"
   module ietf-yang-instance-data {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-yang-instance-data";
     prefix yid;
     import ietf-yang-structure-ext {
       prefix sx;
         "RFC 8791: YANG Data Structure Extensions";
     import ietf-datastores {
       prefix ds;
         "RFC 8342: Network Management Datastore Architecture (NMDA)";
     import ietf-inet-types {
       prefix inet;
         "RFC 6991: Common YANG Data Types";
     import ietf-yang-types {
       prefix yang;
         "RFC 6991: Common YANG Data Types";
     import ietf-netconf-with-defaults {
       prefix ncwd;
         "RFC 6243: With-defaults Capability for NETCONF";
       "IETF NETMOD Working Group";
       "WG Web:   <>
        WG List:  <>
        Author:  Balazs Lengyel

Author: Benoit Claise <>"; description "The module defines the structure and content of YANG instance data sets.

著者:Benoit Claise <> ";説明"モジュールはYangインスタンスデータセットの構造と内容を定義します。

The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document are to be interpreted as described in BCP 14 (RFC 2119) (RFC 8174) when, and only when, they appear in all capitals, as shown here.

「必須」、「必須」、「SEQL」、「推奨する」、「推奨する」、「推奨」、「推奨」、「推奨する」、「推奨」、「推奨」、「推奨」、「推奨」、「推奨する」、「推奨」、「推奨」、「推奨する」、「推奨」、「推奨」、「推奨」、「推奨」、「推奨」、「推奨」、「推奨」、「オプション」、'この文書では、BCP 14(RFC 2119)(RFC 8174)に記載されているように解釈されるべきです。

Copyright (c) 2022 IETF Trust and the persons identified as authors of the code. All rights reserved.

Copyright(C)2022 IETF信頼とコードの著者として識別された人。全著作権所有。

Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (


        This version of this YANG module is part of RFC 9195
        (; see the RFC itself
        for full legal notices.";
     revision 2022-02-17 {
         "Initial revision.";
         "RFC 9195: YANG Instance Data File Format";
     typedef module-with-revision-date {
       type string {
         pattern '[a-zA-Z_][a-zA-Z0-9\-_.]*'
               + '(@\d{4}-(1[0-2]|0[1-9])-(0[1-9]|[1|2][0-9]|3[0-1]))?';
         pattern '.|..|[^xX].*|.[^mM].*|..[^lL].*';
         "A type defining a module name and an optional revision
          date, e.g., ietf-yang-library@2019-01-04.";
     sx:structure instance-data-set {
         "A data structure to define a format for YANG instance
          data.  The majority of the YANG nodes provides metadata
          about the instance data; the instance data itself is
          contained only in the 'content-data' node.";
       leaf name {
         type string;
           "An arbitrary name for the YANG instance data set.  This
            value is primarily used for descriptive purposes.  However,
            when the instance data set is saved to a file, then the
            filename MUST encode the name's value per Section 2
            of RFC 9195.";
       leaf format-version {
         type string {
           pattern '\d{4}-(1[0-2]|0[1-9])-(0[1-9]|[1|2][0-9]|3[0-1])';
         default "2022-01-20";
           "The 'revision' of the 'ietf-yang-instance-data' module
            used to encode this 'instance-data-set'.";
       leaf includes-defaults {
         type ncwd:with-defaults-mode;
         default "report-all";
           "Indicates how data nodes with default values are
            represented for all data nodes contained in the

It uses the same definitions as per Section 3 of RFC 6243 but applied in the context of an instance data file rather than a NETCONF request using the <with-defaults> parameter.

RFC 6243のセクション3と同じ定義を使用しますが、<with defaults>パラメータを使用したNetConf要求ではなくインスタンスデータファイルのコンテキストで適用されます。

            For JSON files, the encoding of the 'report-all-tagged'
            option is as defined in Section 4.8.9 of RFC 8040.";
           "RFC 6243: With-defaults Capability for NETCONF";
       container content-schema {
           "The content schema (i.e., YANG modules) used to create
            the instance data set.
            If not present, the user needs to obtain the information
            through external documents.";
         choice content-schema-spec {
             "Specification of the content-schema.";
           case simplified-inline {
             leaf-list module {
               type module-with-revision-date;
               min-elements 1;
                 "The list of content-defining YANG modules.

The value SHALL start with the module name. If the module contains a revision statement, the revision date SHALL be included in the leaf-list entry, e.g., ietf-yang-library@2019-01-04.

値はモジュール名から始まります。このモジュールに改訂文が含まれている場合、改訂日はリーフリストエントリ、例えばIETF-Yang-Library @ 2019-01-04に含まれます。

                  Usage of this leaf-list implies the modules are
                  used without any deviations and with all features
                  supported. Multiple revisions of the same module
                  MUST NOT be specified.";
           case inline {
             anydata inline-yang-library {
               mandatory true;
                 "Instance data corresponding to the
                  ietf-yang-library@2019-01-04 defining
                  the set of content-defining YANG modules for
                  this instance-data-set.";
           case uri {
             leaf same-schema-as-file {
               type inet:uri;
                 "A reference to another YANG instance data file.
                  This instance data file uses the same
                  content schema as the referenced file.

Referenced files using the 'inline' or the 'simplified-inline' methods MUST be supported. Referenced files using the 'URI method' MAY be supported.

'inline'または '単純化されたインライン'メソッドを使用した参照ファイルをサポートする必要があります。'URIメソッド'を使用した参照ファイルをサポートすることができます。

                  The URL schemes 'file://' and 'https://' MUST
                  be supported; other schemes MAY also be
       leaf-list description {
         type string;
           "Description of the instance data set.";
       leaf contact {
         type string;
           "Contact information for the person or
            organization to whom queries concerning this
            instance data set should be sent.";
       leaf organization {
         type string;
           "Organization responsible for the instance
            data set.";
       leaf datastore {
         type ds:datastore-ref;
           "The identity of the datastore with which the
            instance data set is associated, e.g., the datastore from
            where the data was read, the datastore into which the data
            may be loaded, or the datastore that is being documented.
            If a single specific datastore cannot be specified, the
            leaf MUST be absent.
            If this leaf is absent, then the datastore to which the
            instance data belongs is unspecified.";
       list revision {
         key "date";
           "Instance data sets that are produced as
            a result of some sort of specification or design effort
            SHOULD have at least one revision entry.  For every
            published editorial change, a new unique revision SHOULD
            be added in front of the revisions sequence so that all
            revisions are in reverse chronological order.
            In cases of instance data sets that are read from
            or produced by a server or otherwise subject to
            frequent updates or changes, revision
            SHOULD NOT be present.";
         leaf date {
           type string {
             pattern '\d{4}-(1[0-2]|0[1-9])-(0[1-9]|[1|2][0-9]|3[0-1])';
             "Specifies the date the instance data set
              was last modified. Formatted as YYYY-MM-DD.";
         leaf description {
           type string;
             "Description of this revision of the instance data set.";
       leaf timestamp {
         type yang:date-and-time;
           "The date and time when the instance data set
            was last modified.

In cases of instance data sets that are read from or produced by a server or otherwise subject to frequent updates or changes, the timestamp SHOULD be present.


            If both a revision list entry and timestamp are present,
            the timestamp SHOULD contain the same date as the
            latest revision statement.";
       anydata content-data {
           "Contains the real instance data.
            The data MUST conform to the relevant YANG modules
            specified either in the content-schema or in some other
            implementation-specific manner.";
4. Security Considerations
4. セキュリティに関する考慮事項

The YANG module defined in this document only defines a wrapper structure specifying a format and a metadata header for YANG instance data defined by the content-schema. Because of this, the security considerations template for YANG models in Section 3.7.1 of [RFC8407] is not followed. The instance data is designed to be accessed as a stored file or over any file access method or protocol.


The document does not specify any method to influence the behavior of a server.


The header part is usually not security sensitive; however, sensitive information may be included, in which case it needs to be handled securely, as mentioned below. Information to consider includes:


* If the URI method is used for specification of the content-schema and the URI includes a userinfo subcomponent

* URIメソッドがContent-Schemaの指定に使用され、URIがUserInfoサブコンポーネントを含む場合

* Any description text

* 任意の説明テキスト

The content part may contain sensitive data. The security sensitivity of this data is completely dependent on the content-schema. Depending on the nature of the instance data, instance data files MAY need to be handled securely. The same kind of handling should be applied to this file at rest and in transit that would be needed for the result of a read operation returning the same data. These in-transit protection mechanisms will also mitigate integrity issues when transporting the file.


Instance data files should be protected against modification or unauthorized access using normal file-handling mechanisms. When copying the original files or providing file access for additional users, care should be taken not to reveal information unintentionally.


If the URI method is used for specification of the content-schema, there is a risk that the config schema section in the referenced YANG instance data file may be altered maliciously or even as part of its normal handling. In this case, the content-schema might differ from the one expected. Protecting the integrity and stability of the referenced file should be ensured.


5. IANA Considerations
5. IANAの考慮事項

This document registers one URI and one YANG module.


5.1. URI Registration
5.1. URI登録

This document registers the following URI in the "IETF XML Registry" [RFC3688]:

このドキュメントでは、次のURIを "IETF XMLレジストリ" [RFC3688]に登録します。

URI: urn:ietf:params:xml:ns:yang:ietf-yang-instance-data Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace.

URI:URN:IETF:PARAMS:XML:NS:YANG:IETF-YANG-Instance-Data Registers連絡先:IESG。XML:N / A、要求されたURIはXMLネームスペースです。

5.2. YANG Module Name Registration
5.2. ヤンモジュール名登録

This document registers the following YANG module in the "YANG Module Names" registry [RFC6020]:

このドキュメントでは、次のYANGモジュールが「YANG MODULE名」レジストリ[RFC6020]に登録します。

   Name:  ietf-yang-instance-data
   Namespace:  urn:ietf:params:xml:ns:yang:ietf-yang-instance-data
   Prefix:  yid
   Reference:  RFC 9195
6. References
6. 参考文献
6.1. Normative References
6.1. 引用文献

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <>.

[RFC2119] BRADNER、S、「RFCで使用するためのキーワード」、BCP 14、RFC 2119、DOI 10.17487 / RFC2119、1997年3月、<>。

[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/RFC5234, January 2008, <>.

[RFC5234] Crocker、D.、ED。2008年1月、<、<,2008、<>。

[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, <>.

[RFC6020] Bjorklund、M.、Ed。、 "Yang - ネットワーク構成プロトコルのデータモデリング言語(NetConf)"、RFC 6020、DOI 10.17487 / RFC6020、2010年10月、<https://www.rfc-編集者。org / info / rfc6020>。

[RFC6243] Bierman, A. and B. Lengyel, "With-defaults Capability for NETCONF", RFC 6243, DOI 10.17487/RFC6243, June 2011, <>.

[RFC6243] Bierman、A.およびB. Lengyel、RFC 6243、DOI 10.17487 / RFC6243、2011年6月、<>。

[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, <>.

[RFC6991] Schoenwaelder、J.、Ed。、「共通ヤンデータ型」、RFC 6991、DOI 10.17487 / RFC6991、2013年7月、<>。

[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, <>.

[RFC7950] Bjorklund、M.、Ed。、「Yang 1.1データモデリング言語」、RFC 7950、DOI 10.17487 / RFC7950、2016年8月、<>。

[RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", RFC 7951, DOI 10.17487/RFC7951, August 2016, <>.

[RFC7951] Lhotka、L.、「Yangでモデル化されたデータのJSONエンコーディング」、RFC 7951、DOI 10.17487 / RFC7951、2016年8月、<>。

[RFC7952] Lhotka, L., "Defining and Using Metadata with YANG", RFC 7952, DOI 10.17487/RFC7952, August 2016, <>.

[RFC7952] Lhotka、L.、「Yangとのメタデータの定義」、RFC 7952、DOI 10.17487 / RFC7952、2016年8月、<>。

[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <>.

[RFC8174] Leiba、B.、RFC 2119キーワードの「大文字の曖昧さ」、BCP 14、RFC 8174、DOI 10.17487 / RFC8174、2017年5月、<>。

[RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, <>.

[RFC8342] Bjorklund、M.、Schoenwaelder、J.、Shafer、P.、Watsen、K.、およびR.Wilton、「ネットワーク管理データストアアーキテクチャ(NMDA)」、RFC 8342、DOI 10.17487 / RFC8342、2018年3月、<>。

[RFC8525] Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K., and R. Wilton, "YANG Library", RFC 8525, DOI 10.17487/RFC8525, March 2019, <>.

[RFC8525] Bierman、A.、Bjorklund、M.、Schoenwaelder、J.、Watsen、K.、およびR. Wilton、K.、RFC 8525、DOI 10.17487 / RFC8525、2019年3月、<HTTPS:// / info / rfc8525>。

[RFC8526] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "NETCONF Extensions to Support the Network Management Datastore Architecture", RFC 8526, DOI 10.17487/RFC8526, March 2019, <>.

[RFC8526] Bjorklund、M.、Schoenwaelder、J.、Shafer、P.、Watsen、K.、およびR.Wilton、「ネットワーク管理データストアアーキテクチャをサポートするためのNetConf Extensions」、RFC 8526、DOI 10.17487 / RFC8526、2019年3月、<>。

[RFC8527] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "RESTCONF Extensions to Support the Network Management Datastore Architecture", RFC 8527, DOI 10.17487/RFC8527, March 2019, <>.

[RFC8527] Bjorklund、M.、Schoenwaelder、J.、Shafer、P.、Watsen、K.、およびR.Wilton、RFC 8527、DOI 10.17487 / RFC8527、2019年3月、<>。

[RFC8791] Bierman, A., Björklund, M., and K. Watsen, "YANG Data Structure Extensions", RFC 8791, DOI 10.17487/RFC8791, June 2020, <>.

[RFC8791] Bierman、A.、Björklund、M.、K。Watsen、「Yang Data Struction Extensions」、RFC 8791、DOI 10.17487 / RFC8791、2020年6月、< RFC8791>。

6.2. Informative References
6.2. 参考引用

[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, <>.

[RFC3688] Mealling、M.、 "IETF XML Registry"、BCP 81、RFC 3688、DOI 10.17487 / RFC3688、2004年1月、<>。

[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, <>.

[RFC8340] Bjorklund、M.およびL. Berger、Ed。、「Yang Tree Diagress」、BCP 215、RFC 8340、DOI 10.17487 / RFC8340、2018年3月、<>。

[RFC8407] Bierman, A., "Guidelines for Authors and Reviewers of Documents Containing YANG Data Models", BCP 216, RFC 8407, DOI 10.17487/RFC8407, October 2018, <>.

[RFC8407] Bierman、A。、「Yangデータモデルを含む文書の査読者のためのガイドライン」、BCP 216、RFC 8407、DOI 10.17487 / RFC8407、2018年10月、< RFC8407>。

[RFC8632] Vallin, S. and M. Bjorklund, "A YANG Data Model for Alarm Management", RFC 8632, DOI 10.17487/RFC8632, September 2019, <>.

[RFC8632] Vallin、S.およびM.Bjorklund、「アラーム管理のためのYangデータモデル」、RFC 8632、DOI 10.17487 / RFC8632、2019年9月、<>。

[RFC8641] Clemm, A. and E. Voit, "Subscription to YANG Notifications for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641, September 2019, <>.

[RFC8641] CLEMM、A.およびE. Voit、「データストア更新のためのヤン通知への購読」、RFC 8641、DOI 10.17487 / RFC8641、2019年9月、<>。

[RFC8792] Watsen, K., Auerswald, E., Farrel, A., and Q. Wu, "Handling Long Lines in Content of Internet-Drafts and RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020, <>.

[RFC8792] Watsen、K.、Auerswald、E.、Farrel、A.、およびQ. WU、「インターネットドラフトの内容の長い線の取り扱い」、RFC 8792、DOI 10.17487 / RFC8792、2020年6月2020年6月、<HTTPS//>。

[RFC8808] Wu, Q., Lengyel, B., and Y. Niu, "A YANG Data Model for Factory Default Settings", RFC 8808, DOI 10.17487/RFC8808, August 2020, <>.

[RFC8808] WU、Q.、Lengyel、B.、Y。NIU、「工場出荷時のデフォルト設定のYangデータモデル」、RFC 8808、DOI 10.17487 / RFC8808、2020年8月、<https://www.rfc-編集者.org / info / rfc8808>。

Appendix A. Backwards Compatibility

The concept of "backwards compatibility" and what changes are backwards compatible are not defined for instance data sets as they are highly dependent on the specific use case and the content-schema.


In case of "instance data sets" that are the result of design or specification activity, some changes that may be good to avoid are listed below.


YANG uses the concept of managed entities identified by key values; if the connection between the represented entity and the key value is not preserved during an update, this may lead to the following problems.


* If the key value of a list entry that represents the same managed entity as before is changed, the user may mistakenly identify the list entry as new.

* 前のように同じ管理対象エンティティを表すリストエントリのキー値が変更された場合、ユーザはリストエントリを新規として誤って識別することができる。

* If the meaning of a list entry is changed but the key values are not (e.g., redefining an alarm-type but not changing its alarm-type-id), the change may not be noticed.

* リストエントリの意味が変更されているが、キー値が(例えば、アラームタイプを再定義しているが警報型IDを変更しない)の場合は、変更が見られない場合があります。

* If the key value of a previously removed list entry is reused for a different entity, the change may be misinterpreted as reintroducing the previous entity.

* 以前に削除されたリストエントリのキー値が異なるエンティティに対して再利用されている場合、その変更は前のエンティティを再導入すると誤って解釈される可能性があります。

Appendix B. Detailed Use Cases

This section is non-normative.


B.1. Use Case 1: Early Documentation of Server Capabilities
B.1. ユースケース1:サーバー機能の早期ドキュメンテーション

A server has a number of server capabilities that are defined in YANG modules and can be retrieved from the server using protocols like NETCONF or RESTCONF. Server capabilities include:


* data defined in "ietf-yang-library": YANG modules, submodules, features, deviations, schema-mounts, and datastores supported ([RFC8525]).

* 「IETF-Yang-Library」:Yang Modules、サブモジュール、機能、偏差、スキーママウント、およびデータストアで定義されているデータ([RFC8525])。

* alarms supported ([RFC8632]).

* アラームがサポートされています([RFC8632])。

* data nodes and subtrees that support or do not support on-change notifications ([RFC8641]).

* 変更中の通知をサポートまたはサポートしていないデータノードとサブツリー([RFC8641])。

* netconf-capabilities in ietf-netconf-monitoring.


While it is good practice to allow a client to query these capabilities from the live server, that is often not possible.


Often when a network node is released, an associated Network Management System (NMS) is also released with it. The NMS depends on the capabilities of the server. During NMS implementation, information about server capabilities is needed. If the information is unavailable early in some offline document but only as instance data from the live network node, the NMS implementation will be delayed because it has to wait until the network node is ready. Also, assuming that all NMS implementors will have correctly configured network nodes from which data can be retrieved is a very expensive proposition. (An NMS may handle dozens of node types.)


Network operators often build their own homegrown NMS systems that need to be integrated with a vendor's network node. The operator needs to know the network node's server capabilities in order to do this. Moreover, the network operator's decision to buy a vendor's product may even be influenced by the network node's Operations, Administration, and Maintenance (OAM) feature set documented as the server's capabilities.

ネットワーク事業者は、ベンダーのネットワークノードと統合する必要がある独自のHomeGrown NMSシステムを構築することがよくあります。これを行うには、オペレータはネットワークノードのサーバー機能を知る必要があります。さらに、ベンダーの製品を購入することに対するネットワーク事業者の決定は、ネットワークノードの操作、管理、およびメンテナンス(OAM)機能セットの影響をサーバーの機能として文書化される可能性があります。

Beside NMS implementors, system integrators and many others also need the same information early. Examples could be model-driven testing, generating documentation, etc.


Most server capabilities are relatively stable and change only during upgrade or due to licensing or the addition or removal of hardware. They are usually defined by a vendor at design time, before the product is released. It is feasible and advantageous to define and document them early, e.g., in a YANG instance data file.


It is anticipated that a separate IETF document will define in detail how and which set of server capabilities should be documented.


B.2. Use Case 2: Preloading Data
B.2. ユースケース2:プリロードデータ

There are parts of the configuration that must be fully configurable by the operator. However, a simple default configuration often will be sufficient.


One example is access control groups/roles and related rules. While a sophisticated operator may define dozens of different groups, often a basic (read-only operator, read-write system administrator, security-administrator) triplet will be enough. Vendors will often provide such default configuration data to make device configuration easier for an operator.


The device vendor may define a set of default groups (/nacm:nacm/ groups) and rules for these groups to access specific parts of the common models (/nacm:nacm/rule-list/rule).

デバイスベンダは、共通モデルの特定の部分にアクセスするために、一連のデフォルトグループ(/ NACM:NACM /グループ)とこれらのグループの規則を定義することができます(/ nacm:nacm / rule-list / rule)。

YANG instance data files can be used to document and/or preload the default configuration.


B.3. Use Case 3: Documenting Factory Default Settings
B.3. ユースケース3:工場出荷時のデフォルト設定を文書化します

Nearly every server has a factory default configuration. If the system is really badly misconfigured or if the current configuration is to be abandoned, the system can be reset to the default factory configuration.


YANG instance data can be used to document the factory default configuration. See [RFC8808].




For their valuable comments, discussions, and feedback, we wish to acknowledge Andy Bierman, Juergen Schoenwaelder, Rob Wilton, Joe Clarke, Kent Watsen, Martin Bjorklund, Ladislav Lhotka, Qin Wu, and other members of the Netmod Working Group.

彼らの貴重なコメント、議論、そしてフィードバックのために、私たちはAndy Bierman、Juergen Schoenwaelder、Rob Wilton、Joe Clarke、Kent Watsen、Martin Bjorklund、Ladislav Lhotka、Qin Wu、およびNetMod Working Groupのメンバーを承認したいと思います。

Authors' Addresses


Balazs Lengyel Ericsson Budapest Magyar Tudosok korutja 11 1117 Hungary Email:

Balazs Lengyel Ericsson Budapest Magyar Tudosok Korutja 11 1117ハンガリーメール

Benoit Claise Huawei Email:

Benoit Claise Huawei Eメール