Subject: [netmod] 2 new interoperability issues

From: Andy Bierman <[email-masked]>
Date: Thu, 03 Sep 2009 17:59:40 -0700

Hi,

yang-07, 7.18.3:

   Device deviations are strongly discouraged and SHOULD only be used as
   a last resort.  Telling the application how a device fails to follow
   the standard is no substitute for implementing the standard
   correctly.

IMO, s/SHOULD/MUST/

RFC 2026, 4.1.2:

   The requirement for at least two independent and interoperable
   implementations applies to all of the options and features of the
   specification.  In cases in which one or more options or features
   have not been demonstrated in at least two interoperable
   implementations, the specification may advance to the Draft Standard
   level only if those options or features are removed.

I do not think that adequate interoperability verification
of YANG module server implementations can be done, because
the standard will allow server implementations to substitute
the module capability (+ whatever deviations) as a retrieved value.
Essentially, every server gets to arbitrarily rewrite the
contract specified by the standard, by using deviations.

RFC 2026 requires interoperability verification on
all features.  I do not see how this is possible
if deviations are part of the contract, and some of the
server values for specific YANG leafs are not available
for retrieval.

Advertisement of a module capability is not good
enough for interoperability testing, and YANG is not
standards-worthy if it cannot meet the same direct verification
requirements that SNMP MIB modules are expected
to follow for standards-track advancement.

Andy

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From: David Partain <[email-masked]>
Date: Fri, 4 Sep 2009 08:22:34 +0200

Hi,

(contrib hat on)

I agree with Andy,

Cheers,

David