Subject: [netmod] status terms in YANG and IANA registries

From: Ladislav Lhotka <[email-masked]>
Date: Wed, 05 Dec 2018 16:46:47 +0100

Hi,

sec. 7.21.2 of RFC 7950 defines the "deprecated" and "obsolete" statuses
as follows:

   o  "deprecated" indicates an obsolete definition, but it permits
      new/continued implementation in order to foster interoperability
      with older/existing implementations.

   o  "obsolete" means that the definition is obsolete and SHOULD NOT be
      implemented and/or can be removed from implementations.

Then, RFC 7224 contains these instructions in the IANA Considerations
section:

      "status": Include only if a registration has been deprecated (use
                the value "deprecated") or obsoleted (use the value
                "obsolete").

However, RFC 8126 defines the meaning of the status terms in IANA
registries (sec. 9.6) in the following way:

   Specific entries in a registry can be marked as "obsolete" (no longer
   in use) or "deprecated" (use is not recommended).

I would say that "deprecated" means something else here than in YANG. For
example, the RSA/MD5 algorithm in [1] is marked as "deprecated" because
it was found weak, and implementing it to "foster interoperability" can
hardly be recommended. Instead, "SHOULD NOT implement" applies here,
too.

I think it would be good to either align the semantics of "deprecated"
in YANG with IANA registries, or at least map both IANA terms to
"obsolete" in YANG.

Lada

[1] https://www.iana.org/assignments/dns-sec-alg-numbers/dns-sec-alg-numbers.xhtml

-- 
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67