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The SMI clarification project is an effort to provide clarification of the SMI for SNMP. In implementing a full featured MIB compiler, reviewing all IETF standards-track MIBs and many proprietary MIBs, and writing many MIBs it was shown over and over again that the current definition of the MIB module language had many places where the definitions were ambiguous, incomplete, not understandable, or inconsistent. Many of these problems were the result of choosing ASN.1 as the "Meta language" to define the SNMP MIB module language. (Please note that ASN.1 was a good choice to define the format of SNMP messages, and has shown this in the marketplace with the many complete implementations of the SNMP message protocol. However, using ASN.1 for the "meta language" for the SMI was a poor choice.)
The SNMP MIB module language is used to define the characteristics of management information such as its data-type, allowed access, the unique identification of its class and instances within each class. It also is used to specify relationship information between classes of management information.
The ultimate purpose of the MIB module language is to allow management information to be specified by MIB module designers so that it can be easily understood and implemented by SNMP agent designers and SNMP management application designers. The ideal MIB module language must be easy for new designers to learn, and the meaning of MIB modules written in the language must be clear to reader.
A design team was formed, works completed, and the results are in. The SMI has a new document set (RFCs 2578, 2579, and 2580), and are at FULL standard status!
Several important issues were deferred. These and a new issue came up at the November 1999 IETF meeting. They include the following:
With these additions to the SMI (and to the protocol), SNMP can continue to be useful without switching to another protocol.