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

On 28 Feb 2014, at 13:38, Balazs Lengyel <[email protected]> wrote:

> IMHO we should define in Netconf/YANG how to handle  operational state data.

I think the concept of operational state data should be defined in a way that is independent of NETCONF - the rules should be common for all protocols and other methods that read, create and modify operational state data. The /proc filesystem is IMO a good model.

A corollary to this is that YANG could be used for modelling operational state data under the assumption that its specification is protocol-neutral (which is currently not the case).

In contrast, configuration can be considered NETCONF-specific.

>  
> Balazs
> 
> P.S. "Ephemeral configuration" is a much better name. It is writable configuration and it effects how the node behaves. The name "operational state" carries neither of these two meanings.

My understanding is that operational state data may also include items that are by definition not writable.

Lada 

> 
> On 2014-02-28 13:06, Benoit Claise wrote:
>> 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
>> ].
>> 
>>    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
>> 
>> 
>> 
>> 
>> 
>> 
>> _______________________________________________
>> OPS-AREA mailing list
>> 
>> [email protected]
>> https://www.ietf.org/mailman/listinfo/ops-area
> 
> -- 
> Balazs Lengyel                       Ericsson Hungary Ltd.
> System Manager
> ECN: 831 7320                        Tel: +36-1-437-7320
> Mobile: +36-70-330-7909              email: 
> [email protected]
>  
> 
> _______________________________________________
> OPS-AREA mailing list
> [email protected]
> https://www.ietf.org/mailman/listinfo/ops-area

--
Ladislav Lhotka, CZ.NIC Labs
PGP Key ID: E74E8C0C