YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)
RFC 6020

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Internet Engineering Task Force (IETF)                 M. Bjorklund, Ed.
Request for Comments: 6020                                Tail-f Systems
Category: Standards Track                                   October 2010
ISSN: 2070-1721

                  YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)

Abstract

   YANG is a data modeling language used to model configuration and
   state data manipulated by the Network Configuration Protocol
   (NETCONF), NETCONF remote procedure calls, and NETCONF notifications.

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 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6020.

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   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   described in the Simplified BSD License.

Bjorklund                    Standards Track                    [Page 1]
RFC 6020                          YANG                      October 2010

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Table of Contents

   1. Introduction ....................................................8
   2. Keywords ........................................................8
   3. Terminology .....................................................8
      3.1. Mandatory Nodes ...........................................10
   4. YANG Overview ..................................................11
      4.1. Functional Overview .......................................11
      4.2. Language Overview .........................................13
           4.2.1. Modules and Submodules .............................13
           4.2.2. Data Modeling Basics ...............................13
           4.2.3. State Data .........................................18
           4.2.4. Built-In Types .....................................18
           4.2.5. Derived Types (typedef) ............................19
           4.2.6. Reusable Node Groups (grouping) ....................20
           4.2.7. Choices ............................................21
           4.2.8. Extending Data Models (augment) ....................22
           4.2.9. RPC Definitions ....................................23
           4.2.10. Notification Definitions ..........................24
   5. Language Concepts ..............................................25
      5.1. Modules and Submodules ....................................25
           5.1.1. Import and Include by Revision .....................26
           5.1.2. Module Hierarchies .................................27
      5.2. File Layout ...............................................28
      5.3. XML Namespaces ............................................29
           5.3.1. YANG XML Namespace .................................29
      5.4. Resolving Grouping, Type, and Identity Names ..............29
      5.5. Nested Typedefs and Groupings .............................29
      5.6. Conformance ...............................................30
           5.6.1. Basic Behavior .....................................31
           5.6.2. Optional Features ..................................31
           5.6.3. Deviations .........................................31
           5.6.4. Announcing Conformance Information in the
                  <hello> Message ....................................32