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RE: Scope of NIM

Title: Scope of NIM
Walter, I agree and support your summary.  It is very well articulated.  I would just like to clarify a few sentences ...
You state "we [can] expand the scope of applicability to include CORBA and policy framework. However, this comes at the expense of less practical applicability to MIBs and PIBs".  Regarding the words "less practical applicability", this might be better stated as "less straightforward applicability", and is certainly mitigated by mapping algorithms and guidelines. Regarding the words "scope of applicability", I would prefer to say that "we expand the scope of applicability to the network, its services, devices and policy, including the work of OMG, ITU, DMTF and other standards bodies."  Specifically, CORBA does not address a network information model (but pieces of the problem), and is not the only applicable standard.
Obviously, for an initial scope, I would prefer a much more concrete description and set of goals than to model "the network".  :-) 
-----Original Message-----
From: Weiss, Walter [mailto:wweiss@ellacoya.com]
Sent: Monday, August 21, 2000 11:23 AM
To: 'Tom Scott'; Andrea Westerinen; 'nim@ops.ietf.org'
Subject: Scope of NIM

Tom and Andrea,

Both your insights are well founded. There is clearly a scope issue that needs further consideration. The interest around NIM is driven by the desire to develop a single model that can be applied or mapped to various protocols. If the mappings don't exist or are not used, then we would be building a tower of babel by creating yet another set of data definitions/interfaces. However, even if only two protocols derived from the model, the net effect on the number of distinct data definitions/interfaces would be an n-1 instead of n+1.

With that in mind, I would like to contrast two alternatives for developing an information model. At the last IETF, there was a strong desire to see SMI and SPPI converge. If this happens, we still have to question where the data structures are developed that can be used commonly across both COPS and SNMP. If PIBs are still independently developed from MIBs, the benefits of consistent management of devices across management protocols is greatly deminished. If an effort was undertaken, it would not only be applicable to SNMP and COPS, but also to other data-centric protocols such as LDAP. To develope a data-centric information model does not go as broadly as we had considered in the requirements and the language issues would already be taken care of elsewhere. The main issue would be how to meet the modeling needs of these data centric protocols. For example, how are data structures defined to meet the needs of both device configuration management and higher level policy management? If this question can be addressed to the satisfaction of the MIB and PIB folks, we have clearly achieved an net gain (n-1).

The second alternative for an information model is take this one level higher. By defining not only data structures but also methods and fully specified associations (with independent properties), we expand the scope of applicability to include CORBA and policy framework. However, this comes at the expense of less practical applicability to MIBs and PIBs, as was readily apparent from the discussions at the NIM BOF. Further, this work would be dependent on the specification of a new or existing language for defining this high-level information model. This second alternative also leads to speculation about this works effect on the landscape. Would the net effect be an n-1, n, or n+1? This question must be answered to everyone's satisfaction before broad support can be expected.

If we are going to make progress, I would like to keep the question of scope to be grounded on the question of net effect. If a positive effect can not be demonstrated, this work will not and should not proceed.