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Versions: 00 01

NETMOD Working Group                                              R. Tao
Internet-Draft                                                     Q. Wu
Intended status: Standards Track                                  Huawei
Expires: September 7, 2020                                     B. Claise
                                                                   Cisco
                                                                 L. Geng
                                                                   Z. Du
                                                            China Mobile
                                                           March 6, 2020


                  YANG Data Node Self Explanation Tags
                   draft-tao-netmod-yang-node-tags-01

Abstract

   This document defines a method to tag data node associated with
   telemetry data in YANG Modules.  This YANG data node tagging method
   can be used to provide input, instruction, indication to selection
   filter and filter queries of operational state on a server during a
   "pub/sub" service for YANG datastore updates and provide multiple
   dimensional network visibility analysis when the state of all
   subscriptions of a particular Subscriber to be fetched is huge, so
   that the amount of data to be streamed out to the destination can be
   greatly reduced and only targeted to the characteristics data.

   An extension statement to be used to indicate YANG data node self
   explanation tags that SHOULD be added by the module implementation
   automatically (i.e., outside of configuration).

   A YANG module [RFC7950] is defined, which augments Module tag model
   and provides a list of data node entries to allow for adding or
   removing of data node self explanation tags as well as viewing the
   set of self explanation tags associated with a YANG module.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any




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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 7, 2020.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) 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 Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Data Node tags Use Cases  . . . . . . . . . . . . . . . .   4
       1.1.1.  Multiple Dimensional Performance Measurement
               Information Tagging . . . . . . . . . . . . . . . . .   4
       1.1.2.  Correlated Information Tagging  . . . . . . . . . . .   7
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   8
   2.  Data Node Tag Values  . . . . . . . . . . . . . . . . . . . .   8
     2.1.  IETF Tags Prefix  . . . . . . . . . . . . . . . . . . . .   8
     2.2.  Vendor Tags Prefix  . . . . . . . . . . . . . . . . . . .   8
     2.3.  User Tags Prefix  . . . . . . . . . . . . . . . . . . . .   8
     2.4.  Reserved Tags Prefix  . . . . . . . . . . . . . . . . . .   8
   3.  Data Node Tag Management  . . . . . . . . . . . . . . . . . .   9
     3.1.  Module Design Tagging . . . . . . . . . . . . . . . . . .   9
     3.2.  Implementation Tagging  . . . . . . . . . . . . . . . . .   9
     3.3.  User Tagging  . . . . . . . . . . . . . . . . . . . . . .   9
   4.  Tags Module Structure . . . . . . . . . . . . . . . . . . . .   9
     4.1.  Tags Module Tree  . . . . . . . . . . . . . . . . . . . .   9
   5.  YANG Module . . . . . . . . . . . . . . . . . . . . . . . . .  10
   6.  Guidelines to Model Writers . . . . . . . . . . . . . . . . .  18
     6.1.  Define Standard Tags  . . . . . . . . . . . . . . . . . .  19
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  19
     7.1.  YANG Data Node Tag Prefixes Registry  . . . . . . . . . .  19
     7.2.  IETF YANG Data Node Tags Registry . . . . . . . . . . . .  20
     7.3.  Updates to the IETF XML Registry  . . . . . . . . . . . .  25
     7.4.  Updates to the YANG Module Names Registry . . . . . . . .  25
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  25



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   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  26
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  26
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  26
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  27

1.  Introduction

   As described [I.D-ietf-netmod-module-tags], the use of tags for
   classification and organization is fairly ubiquitous not only within
   IETF protocols, but in the internet itself (e.g., "#hashtags").  A
   module tag defined in [I.D-ietf-netmod-module-tags] is a string
   associated only with a module name at module level.

   At the time of writing this document (2020), there are many data
   models that have been specified or are being specified by the IETF.
   They cover many of the networking protocols and techniques.  However
   data objects defined by these technology specific data models might
   represent a portion of fault, configuration, accounting, performance,
   security the management categories information (e.g., performance
   metric associated with data object type) in many different way, lack
   the same classification criteria and granularity,e.g., sensor data in
   hardware model is defined with fine granularity with value scale and
   value precision while interface model only provides statistics data
   for specific interface type.

   This document defines data node self explanation tags and associates
   them with data nodes within YANG module, which

   o  Provide dictionary meaning for each data node;

   o  Indicate relationship between data nodes within the same YANG
      module or of different YANG modules;

   o  Identify specific service or feature, network element;

   The data node self explanation tags can be used by the client to
   provide input, instruction, indication to selection filter and filter
   queries of configuration or operational state on a server based on
   these data node tags,.e.g.,return specific object type operational
   state related to system-management.  NETCONF clients can discover
   data models with data node self explanation tags supported by a
   NETCONF server via <get-schema> operation.  The data node self
   explanation tag capability can also be advertised via capability
   notification Model [I-D.netconf-notification-capabilities] by the
   NETCONF server or some place where offline document are kept.  These
   self explanation tags may be registered as well as assigned during
   the module definition; assigned by implementations; or dynamically
   defined and set by users.



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   This document defines a YANG module [RFC7950] which augments module
   tag model and provides a list of data node entries to allow for
   adding or removing of self explanation tags as well as viewing the
   set of self explanation tags associated with a data node within YANG
   modules.

   This document defines an extension statement to be used to indicate
   self explanation tags that SHOULD be added by the module
   implementation automatically (i.e., outside of configuration).

   The YANG data model in this document conforms to the Network
   Management Datastore Architecture defined in [RFC8342].

1.1.  Data Node tags Use Cases

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

1.1.1.  Multiple Dimensional Performance Measurement Information Tagging

   Data node tags can be used to express multiple dimensional
   performance metric and properties associated with YANG data nodes or
   data objects modelled with YANG (See Figure 1).

       -----                                     -----
     //     \\                                 //     \\
    | Property+------+                +-------+ Property|
     \\ A   //       |                |        \\ B   //
       -----+     +--V----------------V---+      -----
                  |    YANG Data Node     |
                  |      /Data Object     |
       /---\      +--^----------------^---+      /---\
      /     \        |                |         /     \
     |Metric +-------+                +--------|Metric |
      \  A  /         +-------------+           \  B  /
       \-+-/          |             |            \-+-/
         |            | Metric Group|              |
         -------------|             |---------------
                      +-------------+

                                 Figure 1

   The use of data node tags would be to help filter different discrete
   categories of YANG data nodes across YANG modules supported by a
   device.  If data nodes across YANG modules are suitably tagged and
   learnt by the client from a live server, then an XPath query can be
   used by the client to list all related data nodes supported by a
   device with the same characteristics.  Data node tags can also be



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   used to help coordination when clients are interacting with various
   different devices with the same categories of YANG data node across
   different YANG modules.  For example, one management client could
   mark some specific data node across modules implemented in various
   different devices with the same metric group tag, so consistent
   representation and reporting can be provided for YANG data nodes
   belonging to the same metric group (see Figure 2).












































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   +-----------+---------------+-----------+-----------------------+
   |  Object   | Property      |    Metric |  Metric        Module |
   |  Name     |  Name         |    Group  |   Name                |
   |           |               |           |                       |
   |tunnel-svc | name          |     -     |  -             tunnel |
   |           |               |           |                       |
   |tunnel-svc | create-time   |     -     |  -             tunnel |
   |           |               |           |                       |
   |tunnel-svc | modified-time |     -     |  -                    |
   |           |               |           |                       |
   |tunnel-svc |     -         |lsp-ping-pm| avg-latency  tunnel-pm|
   |           |               |           |                       |
   |tunnel-svc |     -         |lsp-ping-pm| packet-loss  tunnel-pm|
   |           |               |           |                       |
   |tunnel-svc |     -         |lsp-ping-pm| min-latency  tunnel-pm|
   |           |               |           |                       |
   |tunnel-svc |     -         |lsp-ping-pm| max-latency  tunnel-pm|
   |           |               |           |transmitted            |
   |tunnel-svc |     -         |lsp-ping-pm|   -packet    tunnel-pm|
   +-----------+---------------+-----------+-----------------------+

   +---------------------------------------------------------+
   |    Metric    Metric    Metric      Metric    Metric     |
   |    Group      Name    Precision    Scale     Unit       |
   |                                                         |
   | lsp-ping-pm  avg-       1            1         ms       |
   |              latency                                    |
   |                                                         |
   | lsp-ping-pm  packet-    1            1       percentile |
   |              loss                                       |
   |                                                         |
   |                                                         |
   | lsp-ping-pm  min-       1            1         ms       |
   |              latency                                    |
   |                                                         |
   |                                                         |
   | lsp-ping-pm  max-       1            1         ms       |
   |              latency                                    |
   |                                                         |
   |                                                         |
   | lsp-ping-pm  transmitted 1           1                  |
   +---------------------------------------------------------+

                                 Figure 2







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1.1.2.  Correlated Information Tagging

   Another example is the management client could mark some data node
   across different level of YANG modules implemented in the device, the
   management system with the same service tag (e.g., L3VPN Service), so
   root cause can be identified efficiently during service-level
   agreements and performance monitoring or network failure
   troubleshooting.

                      +--------------+
                      | Parent object|
                      +-------^------+
                              |
       -----            +-----+-----+            -----
     //     \\          |Service Tag|          //     \\
    | Property+------+  ++--------+-+ +-------+ Property|
     \\ A   //       |   |        |   |        \\ B   //
       -----+     +--V---V-+    +-V---V--+       -----
                  | Child  |    | Child  |
                  |ObjectA |    |ObjectB |
       /---\      +--^-----+    +-----^--+       /---\
      /     \        |                |         /     \
     |Metric +-------+                +--------|Metric |
      \  A  /                                   \  B  /
       \---/                                     \---/

   +-----------------------------------------------------------+
   |  Service      Metric       Metric     Module     Level    |
   |   Tag         Group        Name                           |
   |                                                           |
   |   L3VPN       L3VPN       maximum      L3VPN     Service  |
   |                           -routes                         |
   |                                                           |
   |  L3VPN     OSPF-Process   total-active  OSPF     Device   |
   |                            routes                         |
   |                                                           |
   |                            total-active                   |
   |  L3VPN     RIP-Process     routes       RIP      Device   |
   |                                                           |
   |                            total-active                   |
   |  L3VPN     BGP-Process     routes       BGP      Device   |
   |                                                           |
   +-----------------------------------------------------------+








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1.2.  Terminology

   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.

2.  Data Node Tag Values

   All data node tags SHOULD begin with a prefix indicating who owns
   their definition.  An IANA registry (Section 7.1) is used to support
   registering data node tag prefixes.  Currently 3 prefixes are
   defined.

   No further structure is imposed by this document on the value
   following the registered prefix, and the value can contain any YANG
   type 'string' characters except carriage-returns, newlines and tabs.
   Therefore, designers, implementers, and users are free to add or not
   add any structure they may require to their own tag values.

2.1.  IETF Tags Prefix

   An IETF tag is a data node tag that has the prefix "ietf:".  All IETF
   data node tags are registered with IANA in a registry defined later
   in this document (Section 7.2).

2.2.  Vendor Tags Prefix

   A vendor tag is a tag that has the prefix "vendor:".  These tags are
   defined by the vendor that implements the module, and are not
   registered; however, it is RECOMMENDED that the vendor include extra
   identification in the tag to avoid collisions such as using the
   enterpise or organization name following the "vendor:" prefix (e.g.,
   vendor:vendor-defined-classifier).

2.3.  User Tags Prefix

   A user tag is any tag that has the prefix "user:".  These tags are
   defined by the user/administrator and are not meant to be registered.
   Users are not required to use the "user:" prefix; however, doing so
   is RECOMMENDED as it helps avoid prefix collisions.

2.4.  Reserved Tags Prefix

   Any tag not starting with the prefix "ietf:", "vendor:" or "user:" is
   reserved for future use.  These tag values are not invalid, but
   simply reserved in the context of specifications (e.g., RFCs).



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3.  Data Node Tag Management

   Tags can become associated with a data node within YANG module in a
   number of ways.  Tags may be defined and associated at module design
   time, at implementation time without the need of live server, or via
   user administrative control . As the main consumer of data node tags
   are users, users may also remove any tag from a live server, no
   matter how the tag became associated with a data node within a YANG
   module.

3.1.  Module Design Tagging

   A data node definition MAY indicate a set of data node tags to be
   added by the module implementer.  These design time tags are
   indicated using the node-tag extension statement.

   If the data node is defined in an IETF standards track document, the
   data node tags MUST be IETF Tags (2.1).  Thus, new data node can
   drive the addition of new IETF tags to the IANA registry defined in
   Section 7.2, and the IANA registry can serve as a check against
   duplication.

3.2.  Implementation Tagging

   An implementation MAY include additional tags associated with data
   node within a YANG module.  These tags SHOULD be IETF Tags (i.e.,
   registered) or vendor specific tags.

3.3.  User Tagging

   Data node tags of any kind, with or without a prefix, can be assigned
   and removed by the user from a live server using normal configuration
   mechanisms.  In order to remove a data node tag from the operational
   datastore, the user adds a matching "masked-tag" entry for a given
   data node within the ietf-data-node-tags Module.

4.  Tags Module Structure

4.1.  Tags Module Tree

   The tree associated with the "ietf-data-node-tags" module follows.
   The meaning of the symbols can be found in [RFC8340].









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        module: ietf-data-node-tags
        augment /tags:module-tags/tags:module:
          +--rw self-explanation-node-tags
             +--rw self-explanation-node* [node-name]
                +--rw node-name            nacm:node-instance-identifier
                +--rw metric-precision     tags:tag
                +--rw metric-scale         tags:tag
                +--rw operation-type       tags:tag
                +--rw parent-grouping      tags:tag
                +--rw data-source-type     tags:tag
                +--rw opm-tag              tags:tag
                +--rw service-tag*         tags:tag
                +--rw task-tag*            tags:tag
                +--rw correlate-group-id   string

5.  YANG Module

<CODE BEGINS> file "ietf-self-explanation-node-tags@2019-05-03.yang"
    module ietf-data-node-tags {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-self-explanation-node-tags";
     prefix ntags;
     import ietf-netconf-acm  { prefix nacm; }
     import ietf-module-tags  { prefix tags; }
     organization
       "IETF NetMod Working Group (NetMod)";
     contact
       "WG Web:  <https://tools.ietf.org/wg/netmod/>
        WG List: <mailto:netmod@ietf.org>
        Author:  Ran Tao
                 <mailto:taoran20@huawei.com>
        Author:  Qin Wu
                 <mailto:bill.wu@huawei.com>";

     // RFC Ed.: replace XXXX with actual RFC number and
     // remove this note.

     description
       "This module describes a mechanism associating self-explanation
        tags with YANG data node within YANG modules. Tags may be IANA
        assigned or privately defined.

        Copyright (c) 2018 IETF Trust and the persons identified as
        authors of the code. All rights reserved.

        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 Simplified BSD License set



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        forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (https://trustee.ietf.org/license-info).

        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.

        This version of this YANG module is part of RFC XXXX
        (https://tools.ietf.org/html/rfcXXXX); see the RFC itself for
        full legal notices.";

     // RFC Ed.: update the date below with the date of RFC publication
     // and RFC number and remove this note.

     revision 2019-05-03 {
       description
         "Initial revision.";
       reference "RFC XXXX: YANG Data Node Tags";
     }
  typedef tag {
    type string {
      length "1..max";
      pattern '[a-zA-Z_][a-zA-Z0-9\-_]*:[\S ]+';
    }
    description
      "A tag value is composed of a standard prefix followed by any type
       'string' value that does not include carriage return, newline or
       tab characters.";
  }
    typedef measurement-precision {
      type int8 {
        range "-8 .. 9";
      }
      description
        "A node using this data type represents a sensor value
         precision range.

         A node of this type SHOULD be defined together with nodes of
         type measurement-units and type measurement-scale.  Together,
         associated nodes of these three types are used to identify the
         semantics of a node of type sensor-value.

         If a node of this type contains a value in the range 1 to 9,
         it represents the number of decimal places in the fractional
         part of an associated sensor-value fixed-point number.



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         If a node of this type contains a value in the range -8 to -1,
         it represents the number of accurate digits in the associated
         sensor-value fixed-point number.

         The value zero indicates the associated sensor-value node is
         not a fixed-point number.

         Server implementers must choose a value for the associated
         sensor-value-precision node so that the precision and accuracy
         of the associated sensor-value node is correctly indicated.

         For example, a component representing a temperature sensor
         that can measure 0 to 100 degrees C in 0.1 degree
         increments, +/- 0.05 degrees, would have a
         sensor-value-precision value of '1', a sensor-value-scale
         value of 'units', and a sensor-value ranging from '0' to
         '1000'.  The sensor-value would be interpreted as
         'degrees C * 10'.";
      reference
        "RFC 3433: Entity Sensor Management Information Base -
                   EntitySensorPrecision";
    }

    typedef measurement-scale {
      type enumeration {
        enum yocto {
          value 1;
          description
            "Measurement scaling factor of 10^-24.";
        }
        enum zepto {
          value 2;
          description
            "Measurement scaling factor of 10^-21.";
        }
        enum atto {
          value 3;
          description
            "Measurement scaling factor of 10^-18.";
        }
        enum femto {
          value 4;
          description
            "Measurement scaling factor of 10^-15.";
        }
        enum pico {
          value 5;
          description



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            "Measurement scaling factor of 10^-12.";
        }
        enum nano {
          value 6;
          description
            "Measurement scaling factor of 10^-9.";
        }
        enum micro {
          value 7;
          description
            "Measurement scaling factor of 10^-6.";
        }
        enum milli {
          value 8;
          description
            "Measurement scaling factor of 10^-3.";
        }
        enum units {
          value 9;
          description
            "Measurement scaling factor of 10^0.";
        }
        enum kilo {
          value 10;
          description
            "Measurement scaling factor of 10^3.";
        }
        enum mega {
          value 11;
          description
            "Measurement scaling factor of 10^6.";
        }
        enum giga {
          value 12;
          description
            "Measurement scaling factor of 10^9.";
        }
        enum tera {
          value 13;
          description
            "Measurement scaling factor of 10^12.";
        }
        enum peta {
          value 14;
          description
            "Measurement scaling factor of 10^15.";
        }
        enum exa {



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          value 15;
          description
            "Measurement scaling factor of 10^18.";
        }
        enum zetta {
          value 16;
          description
            "Measurement scaling factor of 10^21.";
        }
        enum yotta {
          value 17;
          description
            "Measurement scaling factor of 10^24.";
        }
      }
      description
        "A node using this data type represents a data scaling factor,
         represented with an International System of Units (SI) prefix.
         The actual data units are determined by examining a node of
         this type together with the associated sensor-value-type.

         A node of this type SHOULD be defined together with nodes of
         type sensor-value-type and type sensor-value-precision.
         Together, associated nodes of these three types are used to
         identify the semantics of a node of type sensor-value.";
      reference
        "RFC 3433: Entity Sensor Management Information Base -
                   EntitySensorDataScale";
    }

   identity measurement-unit {
       description
        "Base identity for measurement unit.";
      }

     identity ac-volts {
      base measurement-unit;
       description
        "Identity for a measure of electric potential (alternating current).";
     }
     identity dc-volts {
      base measurement-unit;
       description
        "Identity for a measure of electric potential (direct current).";
     }
     identity amperes {
      base measurement-unit;
       description



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        "Identity for a measure of electric current.";
     }
     identity power {
      base measurement-unit;
       description
        "Identity for a measure of power.";
     }
     identity hertz {
      base measurement-unit;
       description
        "Identity for a measure of frequency.";
     }
     identity celsius {
      base measurement-unit;
       description
        "Identity for a measure of temperature.";
     }
     identity rpm {
      base measurement-unit;
       description
        "Identity for a measure of shaft revolutions per minute.";
     }
 extension metric-scale{
       argument tag;
       description
         "The argument 'tag' is of type 'tag'.The metric-scale can be
         used to provide an additional metric scale (e.g., Measurement
         scaling factor of 10^0, 10^-3,10^3) information associated with
         the performance metric data node tag.";
     }
 extension metric-precision {
       argument tag;
       description
         "The argument 'tag' is of type 'tag'.The metric-precision can be
         used to provide an additional metric precision (e.g., the range -8 to -1,
         0, the range 1 to 9) information associated with the performance metric
         data node tag.";
     }

 extension statistics-operation {
       argument tag;
       description
         "The argument 'tag' is of type 'tag'.The statistics-operation can be
         used to provide an additional statistics operation type(e.g., sum,
         min, max,last) information associated with the performance metric
         data node tag.";
     }
 extension data-source-type{



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       argument tag;
       description
         "The argument 'tag' is of type 'tag'.The data-source-type can be
         used to provide an additional data source type (e.g., connectivity,
         resource, hardware,qos,policy) information associated with
         the performance metric data node tag.";
     }
 extension membership-tag {
       argument tag;
       description
         "The argument 'tag' is of type 'tag'.The membership-tag can be
         used to provide an additional multiple source aggregation
         information associated with the performance metric data node
         or interface related data node.";
     }
 extension service-tag {
       argument tag;
       description
         "The argument 'tag' is of type 'tag'.The service-tag can be
         used to provide a service classification information (e.g., tunnel,
         l3vpn,l2vpn) information associated with YANG data node.";
     }

 extension task-tag {
       argument tag;
       description
         "The argument 'tag' is of type 'tag'.The task-tag can be
         used to provide a task classification information (e.g., fault management,
         performance measurement) information associated with YANG data node.";
     }

 extension opm-tag {
       argument tag;
       description
         "The argument 'tag' is of type 'tag'. This extension statement
          is used by module authors to indicate the opm tags that SHOULD be
          added automatically by the system. As such the origin of the
          value for the pre-defined tags should be set to 'system'
          [RFC8342].";
     }

  augment "/tags:module-tags/tags:module" {
    description
      "Augment the Tags module with data node tag attributes";
     container self-explanation-node-tags {
       description
         "Contains the list of data nodes and their associated tags";
       list self-explanation-node {



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         key "node-name";
         description
           "A list of self-explanation nodes and their associated tags";
         leaf node-name {
           type nacm:node-instance-identifier;
           mandatory true;
           description
             "The YANG data node name.";
         }
         leaf metric-precision {
           type tags:tag;
           description
             "The numeric expression precision of performance
              metric related data node.";
         }
         leaf metric-unit {
            type tags:tag;
            description
             "The measurement unit of performance
              metric related data node.";
         }
        leaf metric-scale {
            type tags:tag;
            description
             "The measurement scale of performance
              metric related data node.";
         }
         leaf operation-type{
          type tags:tag;
          description
           "Statistics operation of performance metric related
           data node.";
         }
        leaf data-source-type {
            type tags:tag;
            description
             "The data source type with the data node within YANG module.";
         }
        leaf parent-grouping {
            type tags:tag;
            description
             "The parent-grouping tag can be used to identify multiple source
              (e.g., line card,member link in an aggregated Ethernet
             interface) related to performance metric related data node
              or interface related to data node.";
         }
         leaf  opm-tag {
           type tags:tag;



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           description
             "Tags associated with the data node within YANG module. See
              the IANA 'YANG Data Node Tag Prefixes' registry for reserved
              prefixes and the IANA'IETF YANG Data Node Tags' registry for
              IETF tags.

              The 'operational' state [RFC8342] view of this list is
              constructed using the following steps:

              1) System tags (i.e., tags of 'system' origin) are added.
              2) User configured tags (i.e., tags of 'intended' origin)
              are added.
              3) Any tag that is equal to a masked-tag is removed.";
         }
         leaf service-tag {
          type tags:tag;
          description
           "The node-service-tag can be used to provide a service
           classification information (e.g., tunnel, l3vpn,l2vpn)
           information associated with YANG data node.";
         }
         leaf task-tag {
          type tags:tag;
          description
           "The node-task-tag can be used to provide a task
           classification information (e.g., fault management,
           performance measurement) information associated with
           YANG data node.";
         }
       leaf correlate-group-id {
         type string;
         description
          "This group ID is used to to correlate
          data nodes within the same YANG module or of different YANG modules.";
        }
       }
      }
     }
   }
<CODE ENDS>

6.  Guidelines to Model Writers

   This section updates [RFC8407].







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6.1.  Define Standard Tags

   A module MAY indicate, using node-tag extension statements, a set of
   tags that are to be automatically associated with it (i.e., not added
   through configuration).

    module example-module {
           //...
           import ietf-data-node-tags { prefix ntags; }
           container top {
           ntags:opm-tag "ietf:object-type";
           list X {
            ntags:opm-tag "ietf:property";
           }
          container Y {
          ntags:opm-tag "ietf:metric";
          ntags:statistics-operation "ietf:avg";
          ntags:metric-scale "ietf:milli";
          }
       }
     // ...
    }

   The module writer can use existing standard tags, or use new tags
   defined in the model definition, as appropriate.  For IETF
   standardized modules new data node tags MUST be assigned in the IANA
   registry defined below, see Section Section 7.2.

7.  IANA Considerations

7.1.  YANG Data Node Tag Prefixes Registry

   IANA is asked to create a new registry "YANG Data Node Tag Prefixes"
   grouped under a new "Protocol" category named "YANG Data Node Tag
   Prefixes".

   This registry allocates tag prefixes.  All YANG data node tags SHOULD
   begin with one of the prefixes in this registry.

   Prefix entries in this registry should be short strings consisting of
   lowercase ASCII alpha-numeric characters and a final ":" character.

   The allocation policy for this registry is Specification Required
   [RFC8126].  The Reference and Assignee values should be sufficient to
   identify and contact the organization that has been allocated the
   prefix.

   The initial values for this registry are as follows.



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   +----------+----------------------------------+-----------+----------+
   | Prefix   | Description                      | Reference | Assignee |
   +----------+----------------------------------+-----------+----------+
   | ietf:    | IETF Tags allocated in the IANA  | [This     | IETF     |
   |          | IETF YANG Data Node Tags registry| document] |          |
   |          |                                  |           |          |
   |vendor:   | Non-registered tags allocated by | [This     | IETF     |
   |          | the module implementer.          | document] |          |
   |          |                                  |           |          |
   | user:    | Non-registered tags allocated by | [This     | IETF     |
   |          | and for the user.                | document] |          |
   +----------+----------------------------------+-----------+----------+

   Other standards organizations (SDOs) wishing to allocate their own
   set of tags should allocate a prefix from this registry.

7.2.  IETF YANG Data Node Tags Registry

   IANA is asked to create four new registries "IETF YANG Data Node
   Tags","IETF Metric Precision Tags","IETF Statistics Operation
   Tags","Node Service Tag" grouped under a new "Protocol" category
   "IETF YANG Data Node Tags".  These four registries should be included
   below "YANG Data Node Tag Prefixes" when listed on the same page.

   Four registries allocate tags that have the registered prefix
   "ietf:".  New values should be well considered and not achievable
   through a combination of already existing IETF tags.

   The allocation policy for these four registries is IETF Review
   [RFC8126].

   The initial values for these eight registries are as follows.

   +----------------------------+--------------------------+-----------+
   | Data Node Tag              | Description              | Reference |
   +----------------------------+--------------------------+-----------+
   |                            |                          |           |
   | ietf:object-type           | Relates to object type   | [This     |
   |                            | (e.g., interfaces).      | document] |
   |                            |                          |           |
   | ietf:metric                | Relates to performance   | [This     |
   |                            | metric info              | document] |
   |                            | (e.g., ifstatistics).    |           |
   |                            |                          |           |
   | ietf:metric-group          | Represent metric group   | [This     |
   |                            | (e.g., flow statistics). | document] |
   |                            |                          |           |
   | ietf:property              | Represents a object      | [This     |



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   |                            | property                 | document] |
   |                            | (e.g.,ifindex).          |           |
   +----------------------------+--------------------------+-----------+
   +----------------------------+--------------------------+-----------+
   | Metric Precision           | Description              | Reference |
   +----------------------------+--------------------------+-----------+
   |ietf:minus-eight            |Relates to metric precision [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:minus-seven            |Relates to metric precision [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:minus-sixe             |Relates to metric precision [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:minus-five             |Relates to metric precision [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:minus-four             |Relates to metric precision [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:minus-three            |Relates to metric precision [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:minus-two              |Relates to metric precision [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:minus-one              |Relates to metric precision [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:zero                   |Relates to metric precision [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:one                    |Relates to metric precision [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:two                    |Relates to metric precision [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:three                  |Relates to metric precision [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:four                   | Relates to metric precision [This    |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:five                   | Relates to metric precision  [This   |
   |                            | of performance metric    | document] |
   |                            |                          |           |



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   |ietf:six                    | Relates to metric precision  [This   |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:seven                  | Relates to metric precision  [This   |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:eight                  | Relates to metric precision  [This   |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:nine                   | Relates to metric precision  [This   |
   |                            | of performance metric    | document] |
   +----------------------------+--------------------------+-----------+
   +----------------------------+--------------------------+-----------+
   | Metric scale               | Description              | Reference |
   +----------------------------+--------------------------+-----------+
   |ietf:yocto                  | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:zepto                  | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf:atto                   | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf: femto                 | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf: pico                  | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf: nano                  | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf: micro                 | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf: milli                 | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf: units                 | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf: kilo                  | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf: mega                  | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |



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   |ietf: giga                  | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf: tera                  | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf: peta                  | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf: exa                   | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf: zetta                 | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   |                            |                          |           |
   |ietf: yotta                 | Relates to metric scale  | [This     |
   |                            | of performance metric    | document] |
   +----------------------------+--------------------------+-----------+
   +----------------------------+--------------------------+-----------+
   | Statistics Operation Tag   | Description              | Reference |
   +----------------------------+--------------------------+-----------+
   |ietf:avg                    | Relates to statistics    | [This     |
   |                            | operation(e.g.,average,  | document] |
   |                            | min, max, sum,etc)       |           |
   |ietf:min                    | Relates to statistics    | [This     |
   |                            | operation(e.g.,average,  | document] |
   |                            | min, max, sum,etc)       |           |
   |ietf:max                    | Relates to statistics    | [This     |
   |                            | operation(e.g.,average,  | document] |
   |                            | min, max, sum,etc)       |           |
   |ietf:threshold              | Relates to statistics    | [This     |
   |                            | operation(e.g.,average,  | document] |
   |                            | min, max, threshold,etc) |           |
   +----------------------------+--------------------------+-----------+

   +----------------------------+--------------------------+-----------+
   | Parent Grouping            | Description              | Reference |
   +----------------------------+--------------------------+-----------+
   |ietf:lag                    |Relates to multiple source| [This     |
   |                            |aggregation(e.g.,LAG)     | document] |
   |                            |                          |           |
   |ietf:lag                    |Relates to multiple source| [This     |
   |                            |aggregation(e.g.,linecard)| document] |
   +----------------------------+--------------------------+-----------+
   +----------------------------+--------------------------+-----------+
   | Data source Type           | Description              | Reference |
   +----------------------------+--------------------------+-----------+
   |                            |                          |           |



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   | ietf:service-flow          | Relates to data source   | [This     |
   |                            | type(e.g., microburst).  | document] |
   |                            |                          |           |
   | ietf:topo                  | Relates to data source   | [This     |
   |                            | type(e.g., topology).    | document] |
   |                            |                          |           |
   | ietf:resource              | Relates to data source   | [This     |
   |                            | type info                | document] |
   |                            | (e.g., interface,queue). |           |
   |                            |                          |           |
   | ietf:policy                | Relates to data source   | [This     |
   |                            | type info                | document] |
   |                            |(e.g., acl, routing policy|           |
   |                            |                          |           |
   | ietf:hardware              | Relates to data source   | [This     |
   |                            | type                     | document] |
   |                            | (e.g.,optical module).   |           |
   +----------------------------+--------------------------+-----------+
   +----------------------------+--------------------------+-----------+
   | Service Tag                | Description              | Reference |
   +----------------------------+--------------------------+-----------+
   |ietf:l3vpn                  | Relates to service       | [This     |
   |                            | offering(e.g.,l3vpn      | document] |
   |                            | l2vpn,tunnel,etc)        |           |
   |ietf:l2vpn                  | Relates to service       | [This     |
   |                            | offering(e.g.,l3vpn      | document] |
   |                            | l2vpn,tunnel,etc)        |           |
   |ietf:te-tunnel              | Relates to service       | [This     |
   |                            | offering(e.g.,l3vpn      | document] |
   |                            | l2vpn,tunnel,etc)        |           |
   +----------------------------+--------------------------+-----------+
   +----------------------------+--------------------------+-----------+
   | Task Tag                   | Description              | Reference |
   +----------------------------+--------------------------+-----------+
   |ietf:vpn-diag               | Relates to vpn serivce   | [This     |
   |                            | diagonostic function     | document] |
   |                            |                          |           |
   |ietf:vpn-fullfilment        | Relates to vpn service   | [This     |
   |                            | fullfillment function    | document] |
   |                            |                          |           |
   |ietf:vpn-assurance          | Relates to vpn service   | [This     |
   |                            | assurance function       | document] |
   +----------------------------+--------------------------+-----------+








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7.3.  Updates to the IETF XML Registry

   This document registers a URI in the "IETF XML Registry" [RFC3688].
   Following the format in [RFC3688], the following registration has
   been made:

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

7.4.  Updates to the YANG Module Names Registry

   This document registers one YANG module in the "YANG Module Names"
   registry [RFC6020].  Following the format in [RFC6020], the following
   registration has been made:

     name:
        ietf-data-node-tags
     namespace:
        urn:ietf:params:xml:ns:yang:ietf-data-node-tags
     prefix:
        tags
     reference:
        RFC XXXX (RFC Ed.: replace XXX with actual RFC number and remove
        this note.)

8.  Security Considerations

   The YANG module defined in this memo is designed to be accessed via
   the NETCONF protocol [RFC6241].  The lowest NETCONF layer is the
   secure transport layer and the mandatory-to-implement secure
   transport is SSH [RFC6242].

   This document adds the ability to associate data node tag meta-data
   with YANG modules.  This document does not define any actions based
   on these associations, and none are yet defined, and therefore it
   does not by itself introduce any new security considerations.

   Users of the data node tag-meta data may define various actions to be
   taken based on the data node tag meta-data.  These actions and their
   definitions are outside the scope of this document.  Users will need
   to consider the security implications of any actions they choose to
   define.





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9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [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,
              <https://www.rfc-editor.org/info/rfc8342>.

   [RFC8407]  Bierman, A., "Guidelines for Authors and Reviewers of
              Documents Containing YANG Data Models", BCP 216, RFC 8407,
              DOI 10.17487/RFC8407, October 2018,
              <https://www.rfc-editor.org/info/rfc8407>.

9.2.  Informative References

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.




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   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

Authors' Addresses

   Ran Tao
   Huawei

   Email: taoran20@huawei.com


   Qin Wu
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: bill.wu@huawei.com


   Benoit Claise
   Cisco
   De Kleetlaan 6a b1
   Diegem  1831
   Belgium

   Email: bclaise@cisco.com


   Liang Geng
   China Mobile
   32 Xuanwumen West St, Xicheng District
   Beijing  10053

   Email: gengliang@chinamobile.com


   Zongpeng Du
   China Mobile
   32 Xuanwumen West St, Xicheng District
   Beijing  10053

   Email: duzongpeng@chinamobile.com



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