configuration: writable MIB modules versus NETCONF/YANG modules - part 2

Dear all,

[I bcc'ed some people, with whom I discussed this issue privately. I 
want to make sure they're in the opsarea loop. Sorry, if you receive 
this email twice]

I discussed the following statement with the IESG. I ideally wanted to 
have this statement approved as an IESG statement before the beginning 
of the week, but I realize that it might need some more discussion among 
the OPS community...

    The OPS area recommends the use of NETCONF/YANG standards for
    configuration. IETF working groups are therefore encouraged to use
    the NETCONF/YANG standards for configuration, especially in new
    charters. SNMP MIB modules _creating and_ modifying persistent
    configuration state should only be produced by working groups in
    cases of clear utility and consensus to use SNMP write operations
    for configuration.

Btw, one IESG member insisted on having "_creating and_ modifying" 
instead of "modifying".

Let me focus on a more important issue.
First let me make sure that we agree on one terminology. The 
NETCONF/YANG terminology is in RFC 6244:

   o  Configuration data is the set of writable data that is required to
       transform a system from its initial default state into its current
       state [RFC4741  <http://tools.ietf.org/html/rfc4741>].

    o  Operational state data is a set of data that has been obtained by
       the system at runtime and influences the system's behavior similar
       to configuration data.  In contrast to configuration data,
       operational state is transient and modified by interactions with
       internal components or other systems via specialized protocols.

    o  Statistical data is the set of read-only data created by a system
       itself.  It describes the performance of the system and its
       components.

Operational state data is sometimes called ephemeral (or non-persistent 
configuration data), as opposed to the "configuration data" that is 
persistent.
See RFC 6244 section 4.3.2.x for some useful examples.

The statement has been carefully crafted to cover the 4 different cases:

         SNMP NETCONF/YANG
+-----------------------------------------------------------------+--------------------------------------------------+
             Configuration data  | SHOULD NOT specify writable MIB 
modules    |  SHOULD use NETCONF/YANG          |
|-----------------------------------------------------------------+--------------------------------------------------|
      Operational State data  | Not clear guidelines at time point in 
time  (*)   |   SHOULD use NETCONF/YANG         |
+---------------------------------------------------------------------------------------------------------------------+ 


Let me focus on (*).
Some of you are telling: SNMPset is not enabled in networks, period. 
Don't specify new writable MIB modules, even for operational state data, 
it doesn't make sense.
Some others are telling: Note that this statement limits the discussion 
to configuration data. Note also that there is no standard way to modify 
operational state via NETCONF at this point in time (so it would be 
strange to discourage SNMP if there is no standardized alternative).

I believe we need some more discussion on this specific point. Please 
share your point of view:
- Should we keep the statement as it is, but better explain it? (which 
might require more background, so maybe a draft instead of a brief 
statement)
- Should we extend the statement and remove "persistent" from this 
sentence: SNMP MIB modules creating and modifying persistent 
configuration state should only be produced by working groups in cases 
of clear utility and consensus to use SNMP write operations for 
configuration?
- Something else?

Regards, Benoit

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