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Shepherd writeup

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up. Changes are expected over time.

This version is dated 1 November 2019.

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet
Standard, Informational, Experimental, or Historic)? Why is this the proper
type of RFC? Is this type of RFC indicated in the title page header?


   Proposed Standard.

(2) The IESG approval announcement includes a Document Announcement Write-Up.
Please provide such a Document Announcement Write-Up. Recent examples can be
found in the "Action" announcements for approved documents. The approval
announcement contains the following sections:

Technical Summary:

Relevant content can frequently be found in the abstract and/or introduction of
the document. If not, this may be an indication that there are deficiencies in
the abstract or introduction.

Shepherd (from the Abstract):

    This document defines a collection of common data types to be
    used with the YANG data modeling language. This version of the
    document adds several new type definitions and obsoletes RFC 6991.

Working Group Summary:

Was there anything in WG process that is worth noting? For example, was there
controversy about particular points or were there decisions where the consensus
was particularly rough?


   There was a great debate with regards to if the "ipv[46]-address"
   types defined in RFC 6021 should be changed to not support zones.
   Despite RFC 6991 defining "ipv[46]-address-no-zone" types, many
   continued to be surprised that a zone could be configured.  There
   was a rough 50/50 split, to which the chairs decided that no change
   was the most conservative action.

   There was a last-ditch proposal that seemed viable (to add an
   "ipv[46]-address-with-zone" type and deprecate the existing
   "ipv[46]-address" type, i.e., to have no default) didn't get
   enough support for the chairs to veer off of their "no change"

Document Quality:

Are there existing implementations of the protocol? Have a significant number
of vendors indicated their plan to implement the specification? Are there any
reviewers that merit special mention as having done a thorough review, e.g.,
one that resulted in important changes or a conclusion that the document had no
substantive issues? If there was a MIB Doctor, YANG Doctor, Media Type or other
expert review, what was its course (briefly)? In the case of a Media Type
review, on what date was the request posted?


   The Shepherd is unaware of implementations or commitments,
   but the modules defined in this document are absolutely
   fundamental, so much as that they're coded into the YANG
   utilities `pyang` and `yanglint`, that there is no doubt
   the definitions in this document have been scrutinized.


Who is the Document Shepherd? Who is the Responsible Area Director?


   The Shepherd is Kent Watsen.
   The responsible AD is Robert Wilton.

(3) Briefly describe the review of this document that was performed by the
Document Shepherd. If this version of the document is not ready for
publication, please explain why the document is being forwarded to the IESG.


   The Shepherd reread the entire document, which led to requesting
   an update to address numerous non-technical issues that were
   addressed in the -15 update.

   The Shepherd validated the syntactical correctness of the two
   modules defined in this document using both `yanglint` and `pyang`,
   with neither returning any errors or warnings.

      $ yanglint ietf-yang-types@2023-01-23.yang
      $ yanglint ietf-inet-types@2023-01-23.yang
      $ pyang --ietf --strict ietf-yang-types@2023-01-23.yang
      $ pyang --ietf --strict ietf-inet-types@2023-01-23.yang

(4) Does the document Shepherd have any concerns about the depth or breadth of
the reviews that have been performed?


   The Shepherd does not, anymore, have concerns about
   the depth or breadth of the reviews that have been

(5) Do portions of the document need review from a particular or from broader
perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or
internationalization? If so, describe the review that took place.


   The Shepherd does not believe that portions of the document
   need review from a particular or broader perspective.

(6) Describe any specific concerns or issues that the Document Shepherd has
with this document that the Responsible Area Director and/or the IESG should be
aware of? For example, perhaps he or she is uncomfortable with certain parts of
the document, or has concerns whether there really is a need for it. In any
event, if the WG has discussed those issues and has indicated that it still
wishes to advance the document, detail those concerns here.


   The Shepherd has no specific concerns or issues with this document.

(7) Has each author confirmed that any and all appropriate IPR disclosures
required for full conformance with the provisions of BCP 78 and BCP 79 have
already been filed. If not, explain why?


   The authors confirmed that he is unaware of any IPR related to
   this document.

   Here is the link to the IPR call request:

(8) Has an IPR disclosure been filed that references this document? If so,
summarize any WG discussion and conclusion regarding the IPR disclosures.


   No IPR disclosure has been filed that references this document.

(9) How solid is the WG consensus behind this document? Does it represent the
strong concurrence of a few individuals, with others being silent, or does the
WG as a whole understand and agree with it?


   WG consensus behind this document is reasonably strong, as a
   number of folks engaged in discussions over the course of time.

(10) Has anyone threatened an appeal or otherwise indicated extreme discontent?
If so, please summarise the areas of conflict in separate email messages to the
Responsible Area Director. (It should be in a separate email because this
questionnaire is publicly available.)


   No one has threatened an appeal or otherwise indicated
   discontent (extreme or otherwise).

(11) Identify any ID nits the Document Shepherd has found in this document.
(See and the Internet-Drafts Checklist).
Boilerplate checks are not enough; this check needs to be thorough.


   Idnits was tested against -15, which has a number of "line too long"
   warnings, all of which are due to the author using UTF-8 encodings
   for his name.

   Idnits generated the following warning, which is okay given the document
   explicitly identified invaliad IP address ranges:

     == There are 2 instances of lines with non-RFC6890-compliant IPv4 addresses
     in the document.  If these are example addresses, they should be changed.

   Idnits also generated this warning, for which I cannot determine why:

    Miscellaneous warnings:

    == The document seems to contain a disclaimer for pre-RFC5378 work, but was
       first submitted on or after 10 November 2008.  The disclaimer is usually
       necessary only for documents that revise or obsolete older RFCs, and that
       take significant amounts of text from those RFCs.  If you can contact all
       authors of the source material and they are willing to grant the BCP78
       rights to the IETF Trust, you can and should remove the disclaimer.
       Otherwise, the disclaimer is needed and you can ignore this comment.
       (See the Legal Provisions document at for more information.)

(12) Describe how the document meets any required formal review criteria, such
as the MIB Doctor, YANG Doctor, media type, and URI type reviews.


   The document is written by a YANG Doctor, and hence did not go through a
   YANG Doctor review.

(13) Have all references within this document been identified as either
normative or informative?


   Yes, all the references have been reviewed to be correct.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative references
exist, what is the plan for their completion?


   All normative references are published.

(15) Are there downward normative references references (see RFC 3967)? If so,
list these downward references to support the Area Director in the Last Call


   There are no downward normative references.

(16) Will publication of this document change the status of any existing RFCs?
Are those RFCs listed on the title page header, listed in the abstract, and
discussed in the introduction? If the RFCs are not listed in the Abstract and
Introduction, explain why, and point to the part of the document where the
relationship of this document to the other RFCs is discussed. If this
information is not in the document, explain why the WG considers it unnecessary.


   The publication of this document obsoletes RFC 6991, and it is listed
   as such in the title page header, listed in the abstract, and discussed
   in the introduction.

(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes are
associated with the appropriate reservations in IANA registries. Confirm that
any referenced IANA registries have been clearly identified. Confirm that newly
created IANA registries include a detailed specification of the initial
contents for the registry, that allocations procedures for future registrations
are defined, and a reasonable name for the new registry has been suggested (see
RFC 8126).


   The IANA Considerations section only registers the YANG modules
   and their namespaces.  The registrations look proper, except the
   following change should be applied to reflect latest guidance:

     OLD: Registrant Contact: The NETMOD WG of the IETF.
     NEW: Registrant Contact: The IESG

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find useful in
selecting the IANA Experts for these new registries.


   None of the IANA registration requests require expert review.

(19) Describe reviews and automated checks performed by the Document Shepherd
to validate sections of the document written in a formal language, such as XML
code, BNF rules, MIB definitions, YANG modules, etc.


   The Shepherd validated the syntactical correctness of the module
   using both `yanglint` and `pyang`, with neither returning any
   errors or warnings.

      $ yanglint ietf-yang-types@2023-01-23.yang
      $ yanglint ietf-inet-types@2023-01-23.yang
      $ pyang --ietf --strict ietf-yang-types@2023-01-23.yang
      $ pyang --ietf --strict ietf-inet-types@2023-01-23.yang

(20) If the document contains a YANG module, has the module been checked with
any of the recommended validation tools
( for syntax and
formatting validation? If there are any resulting errors or warnings, what is
the justification for not fixing them at this time? Does the YANG module comply
with the Network Management Datastore Architecture (NMDA) as specified in


   The Shepherd tested the formatting using these two commands:

     $ pyang -f yang --keep-comments --yang-line-length 69 \
       ietf-yang-types@2023-01-23.yang > new.yang && diff \
       ietf-yang-types@2023-01-23.yang new.yang

     $ pyang -f yang --keep-comments --yang-line-length 69
       ietf-inet-types@2023-01-23.yang > new.yang && diff
       ietf-inet-types@2023-01-23.yang new.yang

   Both of which produced substantial albiet innocuous diffs.
   For example, the author chose to indent one less character
   in 'description' statements which, honestly, is equally
   readable, and some may argue as better.  In another example,
   the formatting output was clearly worse, and so immediately
   discounted.  None of the formatting was structually improved.