[netmod] Proposed IANA text for YANG Module Versioning and Semver Drafts

["Rob Wilton (rwilton)" <[e-mail]>]

Hi,

// As an individual contributor

We discussed proposed IANA text at the last NETMOD interim on the YANG versioning work.  Tracked by issue https://github.com/netmod-wg/yang-ver-dt/issues/59

I had the action of updating the text based on comments received in the interim meeting and then sending that text to the list.

The proposed text is below (that is in the current published versions of both drafts).  If the WG has no objections to this text, then the planned next step is to ask IANA for an early review of this text.


IANA section in draft-ietf-netmod-yang-module-versioning-02:

11.2.  Guidance for versioning in IANA maintained YANG modules

   Note for IANA (to be removed by the RFC editor): Please check that
   the registries and IANA YANG modules are referenced in the
   appropriate way.

   IANA is responsible for maintaining and versioning YANG modules that
   are derived from other IANA registries.  For example, "iana-if-
   type.yang" [IfTypeYang] is derived from the "Interface Types (ifType)
   IANA registry" [IfTypesReg], and "iana-routing-types.yang"
   [RoutingTypesYang] is derived from the "Address Family Numbers"
   [AddrFamilyReg] and "Subsequent Address Family Identifiers (SAFI)
   Parameters" [SAFIReg] IANA registries.

   Normally, updates to the registries cause any derived YANG modules to
   be updated in a backwards-compatible way, but there are some cases
   where the registry updates can cause non-backward-compatible updates
   to the derived YANG module.  An example of such an update is the
   2020-12-31 revision of iana-routing-types.yang

   [RoutingTypesDecRevision], where the enum name for two SAFI values
   was changed.

   In all cases, IANA MUST follow the versioning guidance specified in
   Section 3.1, and MUST include a "rev:nbc-changes" substatement to the
   latest revision statement whenever an IANA maintained module is
   updated in a non-backwards-compatible way, as described in
   Section 3.2.

   Note: For published IANA maintained YANG modules that contain non-
   backwards-compatible changes between revisions, a new revision should
   be published with the "rev:nbc-changes" substatement retrospectively
   added to any revisions containing non-backwards-compatible changes.

   Non normative examples of updates to enumeration types in IANA
   maintained modules that would be classified as non-backwards-
   compatible changes are: Changing the status of an enumeration typedef
   to obsolete, changing the status of an enum entry to obsolete,
   removing an enum entry, changing the identifier of an enum entry, or
   changing the described meaning of an enum entry.

   Non normative examples of updates to enumeration types in IANA
   maintained modules that would be classified as backwards-compatible
   changes are: Adding a new enum entry to the end of the enumeration,
   changing the status or an enum entry to deprecated, or improving the
   description of an enumeration that does not change its defined
   meaning.

   Non normative examples of updates to identity types in IANA
   maintained modules that would be classified as non-backwards-
   compatible changes are: Changing the status of an identity to
   obsolete, removing an identity, renaming an identity, or changing the
   described meaning of an identity.

   Non normative examples of updates to identity types in IANA
   maintained modules that would be classified as backwards-compatible
   changes are: Adding a new identity, changing the status or an
   identity to deprecated, or improving the description of an identity
   that does not change its defined meaning.

IANA section for draft-ietf-netmod-yang-semver-02

9.2.  Guidance for YANG Semver in IANA maintained YANG modules

   Note for IANA (to be removed by the RFC editor): Please check that
   the registries and IANA YANG modules are referenced in the
   appropriate way.

   IANA is responsible for maintaining and versioning some YANG modules,
   e.g., iana-if-types.yang [IfTypeYang] and iana-routing-types.yang
   [RoutingTypesYang] .

   In addition to following the rules specified in the IANA
   Considerations section of [I-D.ietf-netmod-yang-module-versioning] ,
   IANA maintained YANG modules MUST also include a YANG Semver revision
   label for all new revisions, as defined in Section 3 .

   The YANG Semver version associated with the new revision MUST follow
   the rules defined in Section 3.3 .

   Note: For IANA maintained YANG modules that have already been
   published, revision labels MUST be retrospectively applied to all
   existing revisions when the next new revision is created, starting at
   version "1.0.0" for the initial published revision, and then
   incrementing according to the YANG Semver version rules specified in
   Section 3.3 .

   Most changes to IANA maintained YANG modules are expected to be
   backwards-compatible changes and classified as MINOR version changes.
   The PATCH version may be incremented instead when only editorial
   changes are made, and the MAJOR version would be incremented if non-
   backwards-compatible major changes are made.

   Given that IANA maintained YANG modules are versioned with a linear
   history, it is anticipated that it should not be necessary to use the
   "_compatible" or "_non_compatible" modifiers to the "Z_COMPAT"
   version element.

Comments welcome.

Thanks,
Rob