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Versions: (draft-rtgyangdt-netmod-module-tags) 00 01 02 03

Network Working Group                                           C. Hopps
Internet-Draft                                          Deutsche Telekom
Updates: rfc6087bis (if approved)                              L. Berger
Intended status: Standards Track                 LabN Consulting, L.L.C.
Expires: April 20, 2019                                    D. Bogdanovic
                                                        October 17, 2018


                            YANG Module Tags
                    draft-ietf-netmod-module-tags-03

Abstract

   This document provides for the association of tags with YANG modules.
   The expectation is for such tags to be used to help classify and
   organize modules.  A method for defining, reading and writing a
   modules tags is provided.  Tags may be standardized and assigned
   during module definition; assigned by implementations; or dynamically
   defined and set by users.  This document provides guidance to future
   model writers and, as such, this document updates
   [I-D.ietf-netmod-rfc6087bis].

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
   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 April 20, 2019.

Copyright Notice

   Copyright (c) 2018 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



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   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   3
   3.  Tag Values  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  IETF Standard Tags  . . . . . . . . . . . . . . . . . . .   3
     3.2.  Vendor Tags . . . . . . . . . . . . . . . . . . . . . . .   3
     3.3.  User Tags . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.4.  Reserved Tags . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Tag Management  . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Module Definition Association . . . . . . . . . . . . . .   4
     4.2.  Implementation Association  . . . . . . . . . . . . . . .   4
     4.3.  Administrative Tagging  . . . . . . . . . . . . . . . . .   4
   5.  Tags Module Structure . . . . . . . . . . . . . . . . . . . .   4
     5.1.  Tags Module Tree  . . . . . . . . . . . . . . . . . . . .   4
     5.2.  Tags Module . . . . . . . . . . . . . . . . . . . . . . .   5
   6.  Other Classifications . . . . . . . . . . . . . . . . . . . .   7
   7.  Guidelines to Model Writers . . . . . . . . . . . . . . . . .   7
     7.1.  Define Standard Tags  . . . . . . . . . . . . . . . . . .   7
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     8.1.  YANG Module Tag Prefix Registry . . . . . . . . . . . . .   8
     8.2.  YANG Module IETF Tag Registry . . . . . . . . . . . . . .   8
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   The use of tags for classification and organization is fairly
   ubiquitous not only within IETF protocols, but in the internet itself
   (e.g., #hashtags).  Tags can be usefully standardized, but they can
   also serve as a non-standardized mechanism available for users to
   define themselves.  Our solution provides for both cases allowing for
   the most flexibility.  In particular, tags may be standardized as
   well as assigned during module definition; assigned by
   implementations; or dynamically defined and set by users.

   This document defines a YANG module [RFC6020] which provides a list
   of module entries to allow for adding or removing of tags as well as
   viewing the set of tags associated with a module.




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

   This document also defines an IANA registry for tag prefixes as well
   as a set of globally assigned tags.

   Section 7 provides guidelines for authors of YANG data models.  This
   section updates [I-D.ietf-netmod-rfc6087bis].

2.  Conventions Used in This Document

   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
   [RFC2119] [RFC8174] when, and only when, they appear in all capitals,
   as shown here.

3.  Tag Values

   All tags begin with a prefix indicating who owns their definition.
   An IANA registry is used to support standardizing tag prefixes.
   Currently 3 prefixes are defined with all others reserved.  No
   further structure is imposed by this document on the value following
   the standard prefix, and the value can contain any yang type 'string'
   characters except carriage-returns, newlines and tabs.

3.1.  IETF Standard Tags

   An IETF standard tag is a tag that has the prefix "ietf:".  All IETF
   standard tags are registered with IANA in a registry defined later in
   this document.

3.2.  Vendor Tags

   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
   standardized; however, it is RECOMMENDED that the vendor include
   extra identification in the tag to avoid collisions such as using the
   enterpise or organization name follwing the "vendor:" prefix (e.g.,
   vendor:example.com:vendor-defined-classifier).

3.3.  User Tags

   A user tag is any tag that has the prefix "user:".  These tags are
   defined by the user/administrator and will never be standardized.





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3.4.  Reserved Tags

   Any tag not starting with the prefix "ietf:", "vendor:" or "user:" is
   reserved for future standardization.

4.  Tag Management

   Tags can become associated with a module in a number of ways.  Tags
   may be defined and associated at module design time, at
   implementation time, or via user administrative control.  As the main
   consumer of tags are users, users may also remove any tag, no matter
   how the tag became associated with a module.

4.1.  Module Definition Association

   A module definition can indicate a set of tags to be added by the
   module implementer.  These design time tags are indicated using the
   module-tag extension statement.  If the module definition will be
   IETF standards track, the tags MUST also be IETF standard tags
   (Section 3.1).  Thus, new modules can drive the addition of new
   standard tags to the IANA registry, and the IANA registry can serve
   as a check against duplication.

4.2.  Implementation Association

   An implementation MAY include additional tags associated with a
   module.  These tags may be standard or vendor specific tags.

4.3.  Administrative Tagging

   Tags of any kind can be assigned and removed with using normal
   configuration mechanisms.

5.  Tags Module Structure

5.1.  Tags Module Tree

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

   module: ietf-module-tags
     +--rw module-tags
        +--rw module* [name]
           +--rw name          yang:yang-identifier
           +--rw tag*          tag
           +--rw masked-tag*   tag





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5.2.  Tags Module

<CODE BEGINS> file "ietf-module-tags@2018-10-17.yang"
module ietf-module-tags {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-module-tags";
  prefix tags;

  import ietf-yang-types {
    prefix yang;
  }

  organization
    "IETF NetMod Working Group (NetMod)";
  contact
    "NetMod Working Group - <netmod@ietf.org>";

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

  description
    "This module describes a mechanism associating tags with 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
     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', 'MAY', and
     'OPTIONAL' in the module text are to be interpreted as described
     in RFC 2119 (https://tools.ietf.org/html/rfc2119).

     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 2018-10-17 {
    description



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      "Initial revision.";
    reference "RFC XXXX: YANG Module 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.";
  }

  extension module-tag {
    argument tag;
    description
      "The argument 'tag' is of type 'tag'. This extension statement is
       used by module authors to indicate the 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'.";
  }

  container module-tags {
    description
      "Contains the list of modules and their associated tags";
    list module {
      key "name";
      description
        "A list of modules and their associated tags";
      leaf name {
        type yang:yang-identifier;
        mandatory true;
        description
          "The YANG module name.";
      }
      leaf-list tag {
        type tag;
        description
          "Tags associated with the module. See the IANA 'YANG Module
           Tag Prefix' registry for reserved prefixes and the IANA 'YANG
           Module IETF Tag' registry for IETF standard tags.

           The operational view of this list is constructed using the following steps:

           1) System added tags are added.
           2) User configured tags are added.



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           3) Any tag that is equal to a masked-tag is removed.";
      }
      leaf-list masked-tag {
        type tag;
        description
          "The list of tags that should not be associated with this
           module. This user can remove (mask) tags by adding
           them to this list. It is not an error to add tags to this
           list that are not associated with the module.";
      }
    }
  }
}
<CODE ENDS>

6.  Other Classifications

   It's worth noting that a different YANG module classification
   document exists [RFC8199].  That document is classifying modules in
   only a logical manner and does not define tagging or any other
   mechanisms.  It divides YANG modules into 2 categories (service or
   element) and then into one of 3 origins: standard, vendor or user.
   It does provide a good way to discuss and identify modules in
   general.  This document defines standard tags to support [RFC8199]
   style classification.

7.  Guidelines to Model Writers

   This section updates [I-D.ietf-netmod-rfc6087bis].

7.1.  Define Standard Tags

   A module can indicate using module-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 module-tags { prefix tags; }

             tags:module-tag "ietf:some-new-tag";
             tags:module-tag "ietf:some-other-tag";
             ...
           }


   The module writer can use existing standard tags, or use new tags
   defined in the model definition, as appropriate.  For standardized



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   modules new tags MUST be assigned in the IANA registry defined below,
   see Section 8.2 below.

8.  IANA Considerations

8.1.  YANG Module Tag Prefix Registry

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

   The allocation policy for this registry is Specification Required
   [RFC5226].

   The initial values for this registry are as follows.

    prefix    description
    --------  ---------------------------------------------------
    ietf:     IETF Standard Tag allocated in the IANA YANG Module
              IETF Tag Registry.
    vendor:   Non-standardized tags allocated by the module implementer.
    user:    Non-standardized tags allocated by and for the user.

   Other SDOs (standard organizations) wishing to standardize their own
   set of tags could allocate a top level prefix from this registry.

8.2.  YANG Module IETF Tag Registry

   This registry allocates prefixes that have the standard prefix
   "ietf:".  New values should be well considered and not achievable
   through a combination of already existing standard tags.

   The allocation policy for this registry is IETF Review [RFC5226].

   The initial values for this registry are as follows.

   +------------------------+------------------------------+-----------+
   |          Tag           |         Description          | Reference |
   +------------------------+------------------------------+-----------+
   |  ietf:rfc8199-element  |    A module for a network    | [RFC8199] |
   |                        |           element.           |           |
   |                        |                              |           |
   |  ietf:rfc8199-service  |    A module for a network    | [RFC8199] |
   |                        |           service.           |           |
   |                        |                              |           |
   | ietf:rfc8199-standard  |    A module defined by a     | [RFC8199] |
   |                        |   standards organization.    |           |
   |                        |                              |           |
   |  ietf:rfc8199-vendor   |    A module defined by a     | [RFC8199] |



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   |                        |           vendor.            |           |
   |                        |                              |           |
   |   ietf:rfc8199-user    |   A module defined by the    | [RFC8199] |
   |                        |            user.             |           |
   |                        |                              |           |
   |     ietf:hardware      |     A module relating to     |   [This   |
   |                        | hardware (e.g., inventory).  | document] |
   |                        |                              |           |
   |     ietf:software      |     A module relating to     |   [This   |
   |                        |  software (e.g., installed   | document] |
   |                        |             OS).             |           |
   |                        |                              |           |
   |        ietf:qos        |    A module for managing     |   [This   |
   |                        |     quality of service.      | document] |
   |                        |                              |           |
   |     ietf:protocol      |   A module representing a    |   [This   |
   |                        |          protocol.           | document] |
   |                        |                              |           |
   | ietf:system-management | A module relating to system  |   [This   |
   |                        |  management (e.g., a system  | document] |
   |                        | management protocol such as  |           |
   |                        |    syslog, TACAC+, SNMP,     |           |
   |                        |        netconf, ...).        |           |
   |                        |                              |           |
   |  ietf:network-service  | A module relating to network |   [This   |
   |                        |   service (e.g., a network   | document] |
   |                        | service protocol such as an  |           |
   |                        | NTP server, DNS server, DHCP |           |
   |                        |        server, etc).         |           |
   |                        |                              |           |
   |        ietf:oam        |    A module representing     |   [This   |
   |                        | Operations, Administration,  | document] |
   |                        | and Maintenance (e.g., BFD). |           |
   |                        |                              |           |
   |      ietf:routing      | A module related to routing. |   [This   |
   |                        |                              | document] |
   |                        |                              |           |
   |     ietf:signaling     |    A module representing     |   [This   |
   |                        |   control plane signaling.   | document] |
   |                        |                              |           |
   |        ietf:lmp        | A module representing a link |   [This   |
   |                        |     management protocol.     | document] |
   +------------------------+------------------------------+-----------+

                     Table 1: IETF Module Tag Registry






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9.  References

9.1.  Normative References

   [I-D.ietf-netmod-rfc6087bis]
              Bierman, A., "Guidelines for Authors and Reviewers of YANG
              Data Model Documents", draft-ietf-netmod-rfc6087bis-20
              (work in progress), March 2018.

   [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>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <https://www.rfc-editor.org/info/rfc5226>.

   [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>.

   [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>.

   [RFC8199]  Bogdanovic, D., Claise, B., and C. Moberg, "YANG Module
              Classification", RFC 8199, DOI 10.17487/RFC8199, July
              2017, <https://www.rfc-editor.org/info/rfc8199>.

9.2.  Informative References

   [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

   Christan Hopps
   Deutsche Telekom

   Email: chopps@chopps.org







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   Lou Berger
   LabN Consulting, L.L.C.

   Email: lberger@labn.net


   Dean Bogdanovic

   Email: ivandean@gmail.com










































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