[netmod] Re: RFC 7950 Inconsistency

Per Andersson <per.ietf@ionio.se> Wed, 24 June 2026 20:43 UTC

MIME-Version: 1.0
References: <f908d758-13a9-43fc-b1d3-1d738a3fa055@nic.cz> <CACvbXWFnyXsNOL+mMt5Pkbch54wKaT5t+743piw-gGNnXy4qDQ@mail.gmail.com> <m27bnotpal.fsf@lhotka.name>
In-Reply-To: <m27bnotpal.fsf@lhotka.name>
From: Per Andersson <per.ietf@ionio.se>
Date: Wed, 24 Jun 2026 22:43:27 +0200
Message-ID: <CACvbXWEf3XAYfpM8vHRFdQusbQc-1YHsbZyWGp4GoqPgsih9ZA@mail.gmail.com>
To: Per Andersson <per.ietf@ionio.se>, Vojtech Vilimek <vojtech.vilimek=40nic.cz@dmarc.ietf.org>, "netmod@ietf.org" <netmod@ietf.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Message-ID-Hash: Y5MS7RMUVJB4KQVEN2JOWPWFQRSIODFP
Precedence: list
Subject: [netmod] Re: RFC 7950 Inconsistency
Archived-At: <https://mailarchive.ietf.org/arch/msg/netmod/Ickb713iHj_MuL-YHdjl6Q9ZTRk>

On Wed, Jun 24, 2026 at 8:39 AM Ladislav Lhotka <ladislav@lhotka.name> wrote:
>
> Per Andersson <per.ietf@ionio.se> writes:
>
> > On Tue, Jun 23, 2026 at 8:49 AM Vojtech Vilimek
> > <vojtech.vilimek=40nic.cz@dmarc.ietf.org> wrote:
> >>
> >> Hi netmod,
> >>
> >> I found an inconsistency in the RFC 7950: YANG 1.1, see below.
> >>
> >> Section 7.1.5 The "import" statement, 3rd paragraph:
> >>     When the optional "revision-date" substatement is present, any
> >>     typedef, grouping, extension, feature, and identity referenced by
> >>     definitions in the local module are taken from the specified revision
> >>     of the imported module.  It is an error if the specified revision of
> >>     the imported module does not exist.  If no "revision-date"
> >>     substatement is present, it is undefined from which revision of the
> >>     module they are taken.
> >>
> >> Section 5.6.5 Implemening a Module, 5th paragraph:
> >>     If a server lists a module C in the "/modules-state/module" list from
> >>     "ietf-yang-library" and there are other modules Ms listed that import
> >>     C without specifying the revision date of module C, the server MUST
> >>     use the definitions from the most recent revision of C listed for
> >>     modules Ms.
> >>
> >>
> >> The revision could not be undefined and the most recent at the same
> >> time. The MUST in overview section make things easier. I want to file
> >> an erratum but before that I am open for discussion.
> >
> > Having a clear rule is desireable, and it already exists as you state.
> >
> > I would expect to take the statements from the latest available YANG
> > module on the system if not stating which version to import explicitly.
>
> An alternative is to leave imported revisions unresolved at the YANG level and modify YANG library so that the actual revisions imported to each module can be specified there. This makes more sense to me as different implementations may have different preferences wrt revisions used.

Perhaps this is solved by using YANG Packages? In any case, it seems
to be a bigger effort that the suggested Errata.

Currently the presented sections contradict each other, and undefined
behavior is never desired.


--
Per


> Lada
>
> >
> >
> > --
> > Per
> >
> > _______________________________________________
> > netmod mailing list -- netmod@ietf.org
> > To unsubscribe send an email to netmod-leave@ietf.org
>
> --
> Ladislav Lhotka <ladislav@lhotka.name>
> PGP Key ID: 0xB8F92B08A9F76C67

[netmod] RFC 7950 Inconsistency Vojtech Vilimek
[netmod] Re: RFC 7950 Inconsistency Per Andersson
[netmod] Re: RFC 7950 Inconsistency Ladislav Lhotka
[netmod] Re: RFC 7950 Inconsistency Per Andersson