Internet Engineering Task Force                        M. Veillette, Ed.
Internet-Draft                                   Trilliant Networks Inc.
Intended status: Standards Track                           A. Pelov, Ed.
Expires: June 22, September 29, 2019                               I. Petrov, Ed.
                                                                  Acklio
                                                       December 19, 2018
                                                          March 28, 2019

                   YANG Schema Item iDentifier (SID)
                         draft-ietf-core-sid-05
                         draft-ietf-core-sid-06

Abstract

   YANG Schema Item iDentifiers (SID) are globally unique 64-bit
   unsigned numbers used to identify YANG items.  This document defines
   the semantics, the registration, and assignment processes of SIDs.
   To enable the implementation of these processes, this document also
   defines a file format used to persist and publish assigned SIDs.

Status of This Memo

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   This Internet-Draft will expire on June 22, September 29, 2019.

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   Copyright (c) 2018 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology and Notation  . . . . . . . . . . . . . . . . . .   3
   3.  ".sid" file lifecycle . . . . . . . . . . . . . . . . . . . .   4
   4.  ".sid" file format  . . . . . . . . . . . . . . . . . . . . .   7   5
   5.  Third party registries  Security Considerations . . . . . . . . . . . . . . . . . . .  11   9
   6.  Security  IANA Considerations . . . . . . . . . . . . . . . . . . .  11
   7. . .   9
     6.1.  Register SID File Format Module . . . . . . . . . . . . .   9
     6.2.  Create new IANA Considerations Registry: "SID Mega-Range" registry . . .   9
       6.2.1.  Structure . . . . . . . . . . . . . . . . . . . . . .  10
       6.2.2.  Allocation policy . . . . . . . . . . . . . . . . . .  10
         6.2.2.1.  First allocation  . . . . . . . . . . . . . . . .  11
     7.1.  Module registration
         6.2.2.2.  Consecutive allocations . . . . . . . . . . . . .  11
       6.2.3.  Initial contents of the Registry  . . . . . . . . . .  11
     6.3.  Create a new IANA Registry: IETF SID Range Registry
           (managed by IANA) . . . . . . . . . . . . . . . . . . . .  11
       6.3.1.  Structure . . . . . . . .  12
     7.2.  "SID mega-range" registry . . . . . . . . . . . . . .  11
       6.3.2.  Allocation policy . . . . . . . . . . . . . . . . . .  12
       7.2.1.  "IANA SID Mega-Range" allocation
       6.3.3.  Initial contents of the registry  . . . . . . . . . .  13
       7.2.2.  "RFC
     6.4.  Create new IANA Registry: "IETF SID range assignment" sub-registry Registry" . . . . . .  13
       6.4.1.  Structure .  14
       7.2.3.  "Specification SID range assignment" sub-registry . .  14
     7.3.  "YANG module assignment" registry . . . . . . . . . . . .  15
   8. . . . . . . .  13
       6.4.2.  Allocation policy . . . . . . . . . . . . . . . . . .  14
       6.4.3.  Initial contents of the registry  . . . . . . . . . .  14
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  15
   9.  14
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     9.1.  15
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  16
     9.2.  15
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  16  15
   Appendix A.  ".sid" file example  . . . . . . . . . . . . . . . .  17
   Authors' Addresses  16
   Appendix B.  SID auto generation  . . . . . . . . . . . . . . . .  25
   Appendix C.  ".sid" file lifecycle  . . . . . . . . . . . . . . .  26

1.  Introduction

   Some of the items defined in YANG [RFC7950] require the use
     C.1.  SID File Creation . . . . . . . . . . . . . . . . . . . .  26
     C.2.  SID File Update . . . . . . . . . . . . . . . . . . . . .  27
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  28

1.  Introduction

   Some of the items defined in YANG [RFC7950] require the use of a
   unique identifier.  In both NETCONF [RFC6241] and RESTCONF [RFC8040],
   these identifiers are implemented using names.  To allow the
   implementation of data models defined in YANG in constrained devices
   and constrained networks, a more compact method to identify YANG
   items is required.  This compact identifier, called SID, is encoded
   using a 64-bit unsigned integer.  The following items are identified
   using SIDs:

   o  identities

   o  data nodes (Note: including those part of a YANG template as
      defined by the 'yang-data' extension.)

   o  RPCs and associated input(s) and output(s)

   o  actions and associated input(s) and output(s)

   o  notifications and associated information

   o  YANG modules, submodules and features

   To minimize their size, in certain positions, SIDs are often could be
   represented as using a difference
   between (signed) delta from a reference SID and the
   current SID and a reference SID. (for example during transmissions).  Such difference is
   itself called "delta", shorthand for "delta-encoded SID".  Conversion
   from SIDs to deltas and back to SIDs is a stateless process.  Each
   protocol implementing deltas must unambiguously define the reference
   SID for each YANG item.

   SIDs are globally unique numbers, a registration system is used in
   order to guarantee their uniqueness.  SIDs are registered in blocks
   called "SID ranges".

   Assignment of SIDs to YANG items can be automated, the recommended
   process to assign SIDs is as follows:

   1.  A tool extracts the different items defined for a specific YANG
       module.

   2.  The list of items is sorted in alphabetical order, 'namespace' in
       descending order, 'identifier' in ascending order.  The
       'namespace' and 'identifier' formats are described in the YANG
       module 'ietf-sid-file' defined in Section 4.

   3.  SIDs are assigned sequentially from the entry point up to the
       size of the registered SID range.  This approach is recommended
       to minimize the serialization overhead, especially when delta
       encoding is implemented.

   4.  If the number of items exceeds the SID range(s) allocated to a
       YANG module, an extra range is added for subsequent assignments. automated.  For more details
   how this could be achieved, please consult Appendix B.

   SIDs are assigned permanently, items introduced by a new revision of
   a YANG module are added to the list of SIDs already assigned.  This
   process can also be automated using the same method described above,
   only unassigned YANG items are processed at step #3.

   Section 3 provides more details about the registration process of
   YANG modules and associated SIDs.  To enable the implementation of
   this registry, Section 4 defines a standard file format used to store
   and publish SIDs.

2.  Terminology and Notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   The following terms are defined in [RFC7950]:

   o  action

   o  feature
   o  module

   o  notification

   o  RPC

   o  schema node

   o  schema tree

   o  submodule

   The following term is defined in [RFC8040]:

   o  yang-data extension

   This specification also makes use of the following terminology:

   o  delta : Difference between the current SID and a reference SID.
      Each protocol that uses delta encoded SIDs MUST define how the
      reference SID is obtained.

   o  item: A schema node, an identity, a module, a submodule or a
      feature defined using the YANG modeling language.

   o  path: A path is a string that identifies a schema node within the
      schema tree.  A path consists of the list of schema node
      identifier(s) separated by slashes ("/").  Schema node
      identifier(s) are always listed from the top-level schema node up
      to the targeted schema node. (e.g. "/ietf-system:system-
      state/clock/current-datetime")

   o  YANG Schema Item iDentifier (SID): Unsigned integer used to
      identify different YANG items.

3.  ".sid" file lifecycle

   YANG is a language designed to model data accessed using one of the
   compatible protocols (e.g.  NETCONF [RFC6241], RESCONF [RFC8040] and
   CoMI [I-D.ietf-core-comi]).  A YANG module defines hierarchies of
   data, including configuration, state data, RPCs, actions and
   notifications.

   YANG modules are not necessarily created in the context of
   constrained applications.  YANG modules can be implemented using
   NETCONF [RFC6241] or RESTCONF [RFC8040] without the need to assign
   SIDs.

   As needed, authors of YANG modules can assign SIDs to their YANG
   modules.  In order to do that, they should first obtain a SID range
   from a registry.  It could be "RFC SID registry and use that range assignment" sub-registry
   as defined in Section Section 7.2.2, the "Specification SID range
   assignment" sub-registry as defined in Section Section 7.2.3 or
   another one, depending on the particular case.  The minimal
   information required for this would be a start SID number and a range
   size, but might include additional details depending on the registry
   policy, which is outside the scope of this document.  Once a SID
   range is registered, the owner can use it to assign or generate ".sid" file/s
   for his YANG module/s.  It is recommended to leave some unallocated SIDs following the allocated range in each ".sid" file in order to
   allow better evolution
   items of the their YANG module in the future.  Generation
   of ".sid" files SHOULD be performed using an automated tool.  Note
   that ".sid" files can only module.  For example how this could be generated for YANG modules and not for
   submodules. achieved,
   please refer to Appendix C.

   Registration of the .sid file associated to a YANG module is optional
   but recommended to promote interoperability between devices and to
   avoid duplicate allocation of SIDs to a single YANG module.
   Different registries might have different requirement requirements for the
   registration and publication of the ".sid" files.

   The following activity  For diagram summarizes the creation of one
   of the possibilities, please refer to the activity diagram on
   Figure 1 in Appendix C.

   Each time a YANG module and or one of its associated .sid file.

       +---------------+
  O    | Creation imported module(s) or included
   sub-module(s) is updated, the ".sid" file MAY need to be updated.
   This update SHOULD also be performed using an automated tool.

   If a new revision requires more SIDs than initially allocated, a new
   SID range MUST be added to the 'assignment-ranges' as defined in
   Section 4.  These extra SIDs are used for subsequent assignments.

   For an example of this update process, see activity diagram Figure 2
   in Appendix C.

4.  ".sid" file format

   ".sid" files are used to persist and publish SIDs assigned to the
   different YANG items of a |
 -|- ->| specific YANG module.  The following YANG
   module   |
 / \   +---------------+
               |
               V
        /-------------\
       / Standardized  \     yes
       \ YANG module ? /-------------+
        \-------------/              |
               | no                  |
               V                     V
        /-------------\      +---------------+
       / Constrained   \ yes | SID range     |
   +-->\ application ? /---->| registration  |<----------+
   |    \-------------/      +---------------+           |
   |           | no                  |                   |
   |           V                     V                   |
   |   +---------------+     +---------------+           |
   +---| YANG module   |     | SID sub-range |           |
       | update        |     | assignment    |<----------+
       +---------------+     +---------------+           |
                                     |                   |
                                     V                   |
                             +---------------+    +-------------+
                             | .sid file     |    | Rework YANG |
                             | generation    |    |    model    |
                             +---------------+    +-------------+
                                     |                   ^
                                     V                   |
                                /----------\  yes        |
                               /  Work in   \ -----------+
                               \  progress  /
                                \----------/
                                     | no
                                     V
                               /-------------\       /-------------\
                              /      RFC      \ no  /     Open      \ no
                              \  publication? /---->\ specification?/---+
                               \-------------/       \-------------/    |
                                      | yes                 | yes       |
                                      |     +---------------+           |
                                      V     V                           V
                              +---------------+                 +---------------+
                              |     IANA      |                 | Third party   |
                              | registration  |                 | registration  |
                              +-------+-------+                 +-------+-------+
                                      |                                 |
                                      +---------------------------------+
                                      V
                                    [DONE]

   Each time a YANG module or one defined the structure of its imported module(s) or included
   sub-module(s) this file, encoding is updated, the ".sid" file MAY need to be updated.
   This update SHOULD also be performed
   using an automated tool.

   If a new revision requires more SIDs than initially allocated, a new
   SID range MUST be added to the 'assignment-ranges' as rules defined in
   Section 4.  These extra SIDs are used for subsequent assignments.

   The following activity diagram summarizes the update of a YANG module
   and its associated .sid file.

          +---------------+
     O    | Update of the |
    -|- ->| YANG module   |
    / \   | or include(s) |
          | or import(s)  |
          +---------------+
                  |
                  V
              /-------------\
             /  New items    \ yes
             \  created  ?   /------+
              \-------------/       |
                     | no           V
                     |       /-------------\      +----------------+
                     |      /  SID range    \ yes | Extra sub-range|
                     |      \  exhausted ?  /---->| assignment     |
                     |       \-------------/      +----------------+
                     |              | no                  |
                     |              +---------------------+
                     |              |
                     |              V
                     |      +---------------+
                     |      | .sid file     |
                     |      | update based  |
                     |      | on previous   |
                     |      | .sid file     |
                     |      +---------------+
                     |              |
                     |              V
                     |       /-------------\      +---------------+
                     |      /  Publicly     \ yes | YANG module   |
                     |      \  available ?  /---->| registration  |
                     |       \-------------/      +---------------+
                     |              | no                  |
                     +--------------+---------------------+
                                    |
                                  [DONE]

4.  ".sid" file format

   ".sid" files are used to persist and publish SIDs assigned to the
   different YANG items of a specific YANG module.  The following YANG
   module defined the structure of this file, encoding is performed
   using the rules defined in [RFC7951].

   <CODE BEGINS> file "ietf-sid-file@2017-11-26.yang" [RFC7951].

   <CODE BEGINS> file "ietf-sid-file@2017-11-26.yang"
   module ietf-sid-file {
     namespace "urn:ietf:params:xml:ns:yang:ietf-sid-file";
     prefix sid;

     import ietf-yang-types {
       prefix yang;
     }

     import ietf-comi {
       prefix comi;
     }

     organization
       "IETF Core Working Group";

     contact
       "Michel Veillette
        <mailto:michel.veillette@trilliant.com>
        Andy Bierman
        <mailto:andy@yumaworks.com>

        Alexander Pelov
        <mailto:a@ackl.io>";

     description
       "This module defines the structure of the .sid files.

        Each .sid file contains the mapping between the different
        string identifiers defined by a YANG module and a
        corresponding numeric value called SID.";

     revision 2017-11-26 {
       description
         "Initial revision.";
       reference
         "[I-D.ietf-core-sid] YANG Schema Item iDentifier (SID)";
     }

     typedef revision-identifier {
       type string {
         pattern '\d{4}-\d{2}-\d{2}';
       }
       description
         "Represents a date in YYYY-MM-DD format.";
     }

     typedef sid {
       type uint64;
       description
         "YANG Schema Item iDentifier";
       reference
         "[I-D.ietf-core-sid] YANG Schema Item iDentifier (SID)";
     }

     typedef schema-node-path {
       type string {
         pattern
           '/[a-zA-Z_][a-zA-Z0-9\-_.]*:[a-zA-Z_][a-zA-Z0-9\-_.]*' +
           '(/[a-zA-Z_][a-zA-Z0-9\-_.]*(:[a-zA-Z_][a-zA-Z0-9\-_.]*)?)*';
       }
       description
         "Identifies a schema-node path string for use in the
          SID registry. This string format follows the rules
          for an instance-identifier, as defined in RFC 7959,
          except that no predicates are allowed.

          This format is intended to support the YANG 1.1 ABNF
          for a schema node identifier, except module names
          are used instead of prefixes, as specified in RFC 7951.";
       reference
         "RFC 7950, The YANG 1.1 Data Modeling Language;
          Section 6.5: Schema Node Identifier;
          RFC 7951, JSON Encoding of YANG Data;
          Section 6.11: The instance-identifier type";
     }

     leaf module-name {
       type yang:yang-identifier;
       description
         "Name of the YANG module associated with this .sid file.";
     }

     leaf module-revision {
       type revision-identifier;
       description
         "Revision of the YANG module associated with this .sid file.
          This leaf is not present if no revision statement is
          defined in the YANG module.";
     }

     list assigment-ranges {
       key "entry-point";
       description
         "SID range(s) allocated to the YANG module identified by
          'module-name' and 'module-revision'.";

       leaf entry-point {
         type comi:sid; sid;
         mandatory true;
         description
           "Lowest SID available for assignment.";
       }

       leaf size {
         type uint64;
         mandatory true;
         description
           "Number of SIDs available for assignment.";
       }
     }

     list items {
       key "namespace identifier";
       description
         "Each entry within this list defined the mapping between
          a YANG item string identifier and a SID. This list MUST
          include a mapping entry for each YANG item defined by
          the YANG module identified by 'module-name' and
          'module-revision'.";

       leaf namespace {
         type enumeration {
           enum module {
             value 0;
             description
               "All module and submodule names share the same
                global module identifier namespace.";
           }
           enum identity {
             value 1;
             description
               "All identity names defined in a module and its
                submodules share the same identity identifier
                namespace.";
           }
           enum feature {
             value 2;
             description
               "All feature names defined in a module and its
                submodules share the same feature identifier
                namespace.";
           }
           enum data {
             value 3;
             description
               "The namespace for all data nodes, as defined in YANG.";
           }
         }
         description
           "Namespace of the YANG item for this mapping entry.";
       }

       leaf identifier {
         type union {
           type yang:yang-identifier;
           type schema-node-path;
         }
         description
           "String identifier of the YANG item for this mapping entry.

            If the corresponding 'namespace' field is 'module',
            'feature', or 'identity', then this field MUST
            contain a valid YANG identifier string.

            If the corresponding 'namespace' field is 'data',
            then this field MUST contain a valid schema node
            path.";
        }

       leaf sid {
         type comi:sid; sid;
         mandatory true;
         description
           "SID assigned to the YANG item for this mapping entry.";
       }
     }
   }
   <CODE ENDS>

5.  Third party registries

   The organization and functioning of third party registries is outside
   the scope of the current document.  The only limitations connected to
   those registries are listed in Section 7.2.

6.  Security Considerations

   The security considerations of [RFC7049] and [RFC7950] apply.

   This document defines a new type of identifier used to encode data
   models defined in YANG [RFC7950].  As such, this identifier does not
   contribute to any new security issues in addition of those identified
   for the specific protocols or contexts for which it is used.

7.

6.  IANA Considerations

   In this section are given specifications for an entry into the module
   registry and two new registries, a SID-range registry and a

6.1.  Register SID
   module registry.

7.1. File Format Module registration

   This document registers one YANG modules in the "YANG Module Names"
   registry [RFC6020]:

   o  name: ietf-sid-file

   o  namespace: urn:ietf:params:xml:ns:yang:ietf-sid-file

   o  prefix: sid

   o  reference: [[THISRFC]]

7.2.

6.2.  Create new IANA Registry: "SID mega-range" Mega-Range" registry

   The name of this registry is "SID mega-range". Mega-Range".  This registry is used
   to record the delegation of the management of a block of SIDs to
   third parties (e.g.  SDO, registrar).  SDOs, registrars, etc).

6.2.1.  Structure

   Each entry in this registry must include:

   o  The entry point (first entry) SID) of the registered SID range. block.

   o  The size of the registered SID range. block.  The size MUST be one
      million (1 000 000) SIDs.

   o  The contact information of the requesting organization including:

   o  Organization name

   o  Primary

      *  The policy of SID range allocations: Public, Private or Both.

      *  Organization name

      *  URL

   The information associated to the Organization name should not be
   publicly visible in the registry, but should be available.  This
   information includes contact name, email address, and phone number

   o  Secondary contact name, and change
   controller email address, and phone number

   The initial entry in this registry is allocated to IANA:

   +-------------+---------+-------------------+
   | Entry Point | Size    | Organization name |
   +-------------+---------+-------------------+
   | 0           | 1000000 | IANA              |
   +-------------+---------+-------------------+ number.

6.2.2.  Allocation policy

   The IANA policies for future additions to this registry are
   "Hierarchical Allocation, Expert "Expert
   Review" [RFC5226].  Prior [RFC8126].

   An organization requesting to manage a first SID Range (and thus have an
   entry in the SID Mega-Range Registry), must ensure the following
   capacities:

   o  The capacity to manage and operate a SID Range Registry.  A SID
      Range Registry MUST provide the following information for all SID
      Ranges allocated by the Registry:

      *  Entry Point of allocated SID Range

      *  Size of allocated SID Range

      *  Type: Public or Private

         +  Public Ranges MUST include at least a reference to the YANG
            module and ".sid" files for that SID Range.

         +  Private Ranges MUST be marked as "Private"

   o  A Policy of allocation, which clearly identifies if the SID Range
      allocations would be Private, Public or Both.

   o  Technical capacity to ensure the sustained operation of the
      registry for a period of at least 5 years.  If Private
      Registrations are allowed, the period must be of at least 10
      years.

6.2.2.1.  First allocation

   For a first allocation to be provided, the requesting organization
   must demonstrate a functional registry infrastructure.

6.2.2.2.  Consecutive allocations

   On subsequent allocation request(s), the organization must
   demonstrate the exhaustion of the prior range.  These conditions need
   to be asserted by the assigned expert(s).

7.2.1.  "IANA

   If that extra-allocation is done within 3 years from the last
   allocation, the experts need to discuss this request on the CORE
   working group mailing list and consensus needs to be obtained before
   allocating new Mega-Range.

6.2.3.  Initial contents of the Registry

   The initial entry in this registry is allocated to IANA:

   +-------------+---------+------------+-------------------+----------+
   | Entry Point | Size    | Allocation | Organization name | URL      |
   +-------------+---------+------------+-------------------+----------+
   | 0           | 1000000 | Public     | IANA              | iana.org |
   +-------------+---------+------------+-------------------+----------+

6.3.  Create a new IANA Registry: IETF SID Mega-Range" allocation Range Registry (managed by
      IANA)

6.3.1.  Structure

   Each entry in this registry must include:

   o  The SID range entry point.

   o  The SID range size.

   o  The YANG module name.

   o  Document reference.

6.3.2.  Allocation policy

   The first million SIDs assigned to IANA is sub-divided as follow: follows:

   o  The range of 0 to 999 (size 1000) is reserved for future extensions.  The IANA
      policy for this range is "IETF review" [RFC5226].  This range is
      reserved for a future uses and no sub-registries are currently "Reserved" as defined for it. in
      [RFC8126].

   o  The range of 1000 to 59,999 (size 59,000) is reserved for YANG
      modules defined in RFCs.  The IANA policy for future additions to this sub-
      registry is "RFC required" [RFC5226].  Allocation within this
      range requires publishing of the associated ".yang" and ".sid"
      files in "Expert Review" [RFC8126].

      *  The Expert MUST verify that the YANG module registry.  The allocation within this
      range is done during IESG review.

   o  The range of 60,000 to 99,999 is reserved for experimental YANG
      modules.  This range MUST NOT be used in operational deployments
      since these SIDs are not globally unique which limit their
      interoperability.  The IANA policy for this range
         allocation is "Experimental
      use" [RFC5226]. made has an RFC (existing RFC) OR is on track to
         become RFC (early allocation with a request from the WG
         chairs).

   o  The SID range of 100,000 to 999,999 is reserved allocated for standardized a YANG
      modules.  The IANA policy for future additions to this sub-
      registry is "Specification Required" [RFC5226].  Allocation within
      this range requires publishing module can follow in one of the associated ".yang" and
      ".sid" files in
      four categories:

      *  SMALL (50 SIDs)

      *  MEDIUM (100 SIDs)

      *  LARGE (250 SIDs)

      *  CUSTOM (requested by the YANG module registry.

   +-------------+---------+------------------------+
   | Entry Point | Size    | IANA policy            |
   +-------------+---------+------------------------+
   | 0           | 1,000   | IETF review            |
   | 1,000       | 59,000  | RFC required           |
   | 60,000      | 40,000  | Experimental use       |
   | 100,000     | 900,000 | Specification Required |
   +-------------+---------+------------------------+

   The author, with a maximum of
         1000 SIDs).  In all cases, the size of a SID range assigned to
         a YANG module should be at least 33% above the current number
         of YANG items.  This headroom allows assignment within the same
         range of new YANG items introduced by subsequent revisions.  A
         larger SID range size may be requested by the authors if this
         recommendation is considered insufficient.  It is important to
         note that an extra additional SID range can be allocated to an
         existing YANG module if the initial range is exhausted.

7.2.2.  "RFC SID range assignment" sub-registry

   o  The name of this sub-registry is "RFC SID range assignment".  This
   sub-registry of "IANA SID Mega-Range" allocation Section 7.2.1
   corresponds 60,000 to the SID entry point 1000, size 59000.  Each entry 99,999 (size 40,000)is reserved for
      experimental YANG modules.  This range MUST NOT be used in
   this sub-registry must include:

   o
      operational deployments since these SIDs are not globally unique
      which limit their interoperability.  The SID IANA policy for this
      range entry point. is "Experimental use" [RFC8126].

   o  The SID range size.

   o  The YANG module name.

   o  The RFC number. of 100,000 to 999,999 (size 900,000) is "Reserved" as
      defined in [RFC8126].

   +-------------+---------+------------------+
   | Entry Point | Size    | IANA policy      |
   +-------------+---------+------------------+
   | 0           | 1,000   | Reserved         |
   | 1,000       | 59,000  | Expert Review    |
   | 60,000      | 40,000  | Experimental use |
   | 100,000     | 900,000 | Reserved         |
   +-------------+---------+------------------+

6.3.3.  Initial contents of the registry

   Initial entries in this registry are as follows:

   +-------------+------+------------------+----------------------+
   | Entry Point | Size | Module name      | RFC number Document reference   |
   +-------------+------+------------------+----------------------+
   | 1000        | 100  | ietf-comi        | [I-D.ietf-core-comi] |
   | 1100        | 50   | ietf-yang-types  | [RFC6021]            |
   | 1150        | 50   | ietf-inet-types  | [RFC6021]            |
   | 1200        | 50   | iana-crypt-hash  | [RFC7317]            |
   | 1250        | 50   | ietf-netconf-acm | [RFC6536]            |
   | 1300        | 50   | ietf-sid-file    | RFCXXXX              |
   | 1500        | 100  | ietf-interfaces  | [RFC7223]            |
   | 1600        | 100  | ietf-ip          | [RFC7277]            |
   | 1700        | 100  | ietf-system      | [RFC7317]            |
   | 1800        | 400  | iana-if-type     | [RFC7224]            |
   +-------------+------+------------------+----------------------+

   // RFC Ed.: replace XXXX with RFC number assigned to this draft.

   For allocation, RFC publication of the YANG module is required as per
   [RFC5226].
   [RFC8126].  The YANG module must be registered in the "YANG module
   Name" registry according to the rules specified in section 14 of
   [RFC6020].

7.2.3.  "Specification SID range assignment" sub-registry

   The name of this sub-registry is "Specification SID range
   assignment".  This sub-registry of "IANA SID Mega-Range" allocation
   Section 7.2.1 corresponds to the SID entry point 100000, size 900000.
   Each entry in this sub-registry must include:

   o  The SID range entry point.

   o  The

6.4.  Create new IANA Registry: "IETF SID range size.

   o  The YANG module name.

   o  The name of the standard organization

   o  The specification identifier or URI

7.3.  "YANG module assignment" registry Registry"

   The name of this registry is "YANG module assignment". "IETF SID Registry".  This registry is
   used to track which YANG modules have been assigned and record the
   specific allocation of individual SIDs YANG items assignment. module items.

6.4.1.  Structure

   Each entry in this registry must include:

   o  The YANG module name.  This module name must be present in the
      "Name" column of the "YANG Module Names" registry.

   o  The  A link to the associated ".yang" file(s)

   o  The associated ".sid" file.  This file

   The validity link must be
      present in the "File" column of the ".yang" and ".sid" files added to this registry
   MUST be verified. "YANG Module Names" registry.

   o  The syntax of link to the registered ".yang" and ".sid" files must be
      valid.

   o  Each YANG item defined by the registered ".yang" file must have a
      corresponding SID assigned which defines the allocation.

   o  The number of actually allocated SIDs in the ".sid" file.

   o  Each SID

   The ".sid" file is assigned to a single YANG item, duplicate assignment stored by IANA.

6.4.2.  Allocation policy

   The allocation policy is not allowed.

   o Expert review.  The SID range(s) defined in Expert MUST ensure that
   the following conditions are met:

   o  The ".sid" file must be unique, must
      not conflict with any other SID ranges has a valid structure:

      *  The ".sid" file MUST be a valid JSON file following the
         structure of the module defined in already
      registered ".sid" files. RFCXXXX (RFC Ed: replace XXX
         with RFC number assigned to this draft).

   o  The ownership of ".sid" file allocates individual SIDs ONLY in the SID range(s) should be verified.

   The IANA policy Ranges
      for future additions this YANG module (as allocated in the IETF SID Range
      Registry):

      *  All SIDs in this ".sid" file MUST be within the ranges
         allocated to this registry is "First Come
   First Served" YANG module in the "IETF SID Range Registry".

   o  If another ".sid" file has already allocated SIDs for this YANG
      module (e.g.  for older or newer versions of the YANG module), the
      YANG items are assigned the same SIDs as described in [RFC5226].

8. the the other ".sid"
      file.

   o  SIDs never change.

6.4.3.  Initial contents of the registry

   None.

7.  Acknowledgments

   The authors would like to thank Andy Bierman, Carsten Bormann,
   Abhinav Somaraju, Laurent Toutain, Randy Turner and Peter van der
   Stok for their help during the development of this document and their
   useful comments during the review process.

9.

8.  References

9.1.

8.1.  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>.

   [RFC7049]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
              October 2013, <https://www.rfc-editor.org/info/rfc7049>.

   [RFC7120]  Cotton, M., "Early IANA Allocation of Standards Track Code
              Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January
              2014, <https://www.rfc-editor.org/info/rfc7120>.

   [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>.

   [RFC7951]  Lhotka, L., "JSON Encoding of Data Modeled with YANG",
              RFC 7951, DOI 10.17487/RFC7951, August 2016,
              <https://www.rfc-editor.org/info/rfc7951>.

9.2.

8.2.  Informative References

   [I-D.ietf-core-comi]
              Veillette, M., Stok, P., Pelov, A., and A. Bierman, "CoAP
              Management Interface", draft-ietf-core-comi-04 (work in
              progress), November 2018.

   [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>.

   [RFC6021]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6021, DOI 10.17487/RFC6021, October 2010,
              <https://www.rfc-editor.org/info/rfc6021>.

   [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>.

   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536,
              DOI 10.17487/RFC6536, March 2012,
              <https://www.rfc-editor.org/info/rfc6536>.

   [RFC7223]  Bjorklund, M., "A YANG Data Model for Interface
              Management", RFC 7223, DOI 10.17487/RFC7223, May 2014,
              <https://www.rfc-editor.org/info/rfc7223>.

   [RFC7224]  Bjorklund, M., "IANA Interface Type YANG Module",
              RFC 7224, DOI 10.17487/RFC7224, May 2014,
              <https://www.rfc-editor.org/info/rfc7224>.

   [RFC7277]  Bjorklund, M., "A YANG Data Model for IP Management",
              RFC 7277, DOI 10.17487/RFC7277, June 2014,
              <https://www.rfc-editor.org/info/rfc7277>.

   [RFC7317]  Bierman, A. and M. Bjorklund, "A YANG Data Model for
              System Management", RFC 7317, DOI 10.17487/RFC7317, August
              2014, <https://www.rfc-editor.org/info/rfc7317>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [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>.

Appendix A.  ".sid" file example

   The following .sid file (ietf-system@2014-08-06.sid) have been
   generated using the following yang modules:

   o  ietf-system@2014-08-06.yang

   o  ietf-yang-types@2013-07-15.yang

   o  ietf-inet-types@2013-07-15.yang

   o  ietf-netconf-acm@2012-02-22.yang

   o  iana-crypt-hash@2014-04-04.yang

   {
     "assignment-ranges": [
       {
         "entry-point": 1700,
         "size": 100
       }
     ],
     "module-name": "ietf-system",
     "module-revision": "2014-08-06",
     "items": [
       {
         "namespace": "module",
         "identifier": "ietf-system",
         "sid": 1700
       },
       {
         "namespace": "identity",
         "identifier": "authentication-method",
         "sid": 1701
       },
       {
         "namespace": "identity",
         "identifier": "local-users",
         "sid": 1702
       },
       {
         "namespace": "identity",
         "identifier": "radius",
         "sid": 1703
       },
       {
         "namespace": "identity",
         "identifier": "radius-authentication-type",
         "sid": 1704
       },
       {
         "namespace": "identity",
         "identifier": "radius-chap",
         "sid": 1705
       },
       {
         "namespace": "identity",
         "identifier": "radius-pap",
         "sid": 1706
       },
       {
         "namespace": "feature",
         "identifier": "authentication",
         "sid": 1707
       },
       {
         "namespace": "feature",
         "identifier": "dns-udp-tcp-port",
         "sid": 1708
       },
       {
         "namespace": "feature",
         "identifier": "local-users",
         "sid": 1709
       },
       {
         "namespace": "feature",
         "identifier": "ntp",
         "sid": 1710
       },
       {
         "namespace": "feature",
         "identifier": "ntp-udp-port",
         "sid": 1711
       },
       {
         "namespace": "feature",
         "identifier": "radius",
         "sid": 1712
       },
       {
         "namespace": "feature",
         "identifier": "radius-authentication",
         "sid": 1713
       },
       {
         "namespace": "feature",
         "identifier": "timezone-name",
         "sid": 1714
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:set-current-datetime",
         "sid": 1715
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:set-current-datetime/
                        current-datetime",
         "sid": 1716
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system",
         "sid": 1717
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system-restart",
         "sid": 1718
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system-shutdown",
         "sid": 1719
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system-state",
         "sid": 1720
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system-state/clock",
         "sid": 1721
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system-state/clock/boot-datetime",
         "sid": 1722
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system-state/clock/
                        current-datetime",
         "sid": 1723
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system-state/platform",
         "sid": 1724
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system-state/platform/machine",
         "sid": 1725
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system-state/platform/os-name",
         "sid": 1726
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system-state/platform/os-release",
         "sid": 1727
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system-state/platform/os-version",
         "sid": 1728
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/authentication",
         "sid": 1729
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/authentication/user",
         "sid": 1730
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/authentication/
                        user-authentication-order",
         "sid": 1731
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/authentication/user/
                        authorized-key",
         "sid": 1732
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/authentication/user/
                        authorized-key/algorithm",
         "sid": 1733
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/authentication/user/
                        authorized-key/key-data",
         "sid": 1734
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/authentication/user/
                        authorized-key/name",

         "sid": 1735
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/authentication/user/
                        name",
         "sid": 1736
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/authentication/user/
                        password",
         "sid": 1737
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/clock",
         "sid": 1738
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/clock/timezone-name",
         "sid": 1739
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/clock/timezone-utc-offset",
         "sid": 1740
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/contact",
         "sid": 1741
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/dns-resolver",
         "sid": 1742
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/dns-resolver/options",
         "sid": 1743
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/dns-resolver/options/
                        attempts",

         "sid": 1744
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/dns-resolver/options/
                        timeout",
         "sid": 1745
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/dns-resolver/search",
         "sid": 1746
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/dns-resolver/server",
         "sid": 1747
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/dns-resolver/server/name",
         "sid": 1748
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/dns-resolver/server/
                        udp-and-tcp",
         "sid": 1749
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/dns-resolver/server/
                        udp-and-tcp/address",
         "sid": 1750
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/dns-resolver/server/
                        udp-and-tcp/port",
         "sid": 1751
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/hostname",
         "sid": 1752
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/location",
         "sid": 1753
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/ntp",
         "sid": 1754
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/ntp/enabled",
         "sid": 1755
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/ntp/server",
         "sid": 1756
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/ntp/server/
                        association-type",
         "sid": 1757
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/ntp/server/iburst",
         "sid": 1758
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/ntp/server/name",
         "sid": 1759
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/ntp/server/prefer",
         "sid": 1760
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/ntp/server/udp",
         "sid": 1761
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/ntp/server/udp/address",
         "sid": 1762

       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/ntp/server/udp/port",
         "sid": 1763
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/radius",
         "sid": 1764
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/radius/options",
         "sid": 1765
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/radius/options/attempts",
         "sid": 1766
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/radius/options/timeout",
         "sid": 1767
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/radius/server",
         "sid": 1768
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/radius/server/
                        authentication-type",
         "sid": 1769
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/radius/server/name",
         "sid": 1770
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/radius/server/udp",
         "sid": 1771
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/radius/server/udp/
                        address",
         "sid": 1772
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/radius/server/udp/
                        authentication-port",
         "sid": 1773
       },
       {
         "namespace": "data",
         "identifier": "/ietf-system:system/radius/server/udp/
                        shared-secret",
         "sid": 1774
       }
     ]
   }

Appendix B.  SID auto generation

   Assignment of SIDs to YANG items can be automated, the recommended
   process to assign SIDs is as follows:

   1.  A tool extracts the different items defined for a specific YANG
       module.

   2.  The list of items is sorted in alphabetical order, 'namespace' in
       descending order, 'identifier' in ascending order.  The
       'namespace' and 'identifier' formats are described in the YANG
       module 'ietf-sid-file' defined in Section 4.

   3.  SIDs are assigned sequentially from the entry point up to the
       size of the registered SID range.  This approach is recommended
       to minimize the serialization overhead, especially when delta
       encoding is implemented.

   4.  If the number of items exceeds the SID range(s) allocated to a
       YANG module, an extra range is added for subsequent assignments.

   Changes of SID files can also be automated using the same method
   described above, only unassigned YANG items are processed at step #3.

Appendix C.  ".sid" file lifecycle

   Before assigning SIDs to their YANG modules, YANG module authors must
   acquire a SID range from a "SID Range Registry".  If the YANG module
   is part of an IETF draft or RFC, the SID range need to be acquired
   from the "IETF SID Range Registry" as defined in Section 6.3.  For
   the other YANG modules, the authors can acquire a SID range from any
   "SID Range Registry" of their choice.

   Once the SID range is acquired, the owner can use it to generate
   ".sid" file/s for his YANG module/s.  It is recommended to leave some
   unallocated SIDs following the allocated range in each ".sid" file in
   order to allow better evolution of the YANG module in the future.
   Generation of ".sid" files should be performed using an automated
   tool.  Note that ".sid" files can only be generated for YANG modules
   and not for submodules.

C.1.  SID File Creation

   The following activity diagram summarizes the creation of a YANG
   module and its associated .sid file.

       +---------------+
  O    | Creation of a |
 -|- ->| YANG module   |
 / \   +---------------+
               |
               V
        /-------------\
       / Standardized  \     yes
       \ YANG module ? /-------------+
        \-------------/              |
               | no                  |
               V                     V
        /-------------\      +---------------+
       / Constrained   \ yes | SID range     |
   +-->\ application ? /---->| registration  |<----------+
   |    \-------------/      +---------------+           |
   |           | no                  |                   |
   |           V                     V                   |
   |   +---------------+     +---------------+           |
   +---| YANG module   |     | SID sub-range |           |
       | update        |     | assignment    |<----------+
       +---------------+     +---------------+           |
                                     |                   |
                                     V                   |
                             +---------------+    +-------------+
                             | .sid file     |    | Rework YANG |
                             | generation    |    |    model    |
                             +---------------+    +-------------+
                                     |                   ^
                                     V                   |
                                /----------\  yes        |
                               /  Work in   \ -----------+
                               \  progress  /
                                \----------/
                                     | no
                                     V
                               /-------------\       /-------------\
                              /      RFC      \ no  /     Open      \ no
                              \  publication? /---->\ specification?/---+
                               \-------------/       \-------------/    |
                                      | yes                 | yes       |
                                      |     +---------------+           |
                                      V     V                           V
                              +---------------+                 +---------------+
                              |     IANA      |                 | Third party   |
                              | registration  |                 | registration  |
                              +-------+-------+                 +-------+-------+
                                      |                                 |
                                      +---------------------------------+
                                      V
                                    [DONE]

                          Figure 1: SID Lifecycle

C.2.  SID File Update

   The following Activity diagram summarizes the update of a YANG module
   and its associated .sid file.

          +---------------+
     O    | Update of the |
    -|- ->| YANG module   |
    / \   | or include(s) |
          | or import(s)  |
          +---------------+
                  |
                  V
              /-------------\
             /  New items    \ yes
             \  created  ?   /------+
              \-------------/       |
                     | no           V
                     |       /-------------\      +----------------+
                     |      /  SID range    \ yes | Extra sub-range|
                     |      \  exhausted ?  /---->| assignment     |
                     |       \-------------/      +----------------+
                     |              | no                  |
                     |              +---------------------+
                     |              |
                     |              V
                     |      +---------------+
                     |      | .sid file     |
                     |      | update based  |
                     |      | on previous   |
                     |      | .sid file     |
                     |      +---------------+
                     |              |
                     |              V
                     |       /-------------\      +---------------+
                     |      /  Publicly     \ yes | YANG module   |
                     |      \  available ?  /---->| registration  |
                     |       \-------------/      +---------------+
                     |              | no                  |
                     +--------------+---------------------+
                                    |
                                  [DONE]

                    Figure 2: YANG and SID file update

Authors' Addresses
   Michel Veillette (editor)
   Trilliant Networks Inc.
   610 Rue du Luxembourg
   Granby, Quebec  J2J 2V2
   Canada

   Phone: +14503750556
   Email: michel.veillette@trilliant.com

   Alexander Pelov (editor)
   Acklio
   1137A avenue des Champs Blancs
   Cesson-Sevigne, Bretagne  35510
   France

   Email: a@ackl.io

   Ivaylo Petrov (editor)
   Acklio
   1137A avenue des Champs Blancs
   Cesson-Sevigne, Bretagne  35510
   France

   Email: ivaylo@ackl.io