Information Modeling

Information modeling is one aspect of describing a managed environment, because it explains concepts from a high-level perspective up to specific details, and it does this in a neutral way without defining implementation details. It provides common definitions and terminology that help structure information. This can be applied for designing processes, applications, interfaces between software components, and other business areas.

In addition, information models help operators and users understand the general concepts. Therefore, information models are also called abstract models or conceptual models. They are protocol- and implementation-neutral. We use the following definition of the information model from RFC 3198:

"An abstraction and representation of the entities in a managed environment—their properties, operations, and relationships. It is independent of any specific repository, application, protocol, or platform."

A data model instantiates the information model by specifying the implementation details. Again, we use the definition from RFC 3198:

"A data model is basically the rendering of an information model according to a specific set of mechanisms for representing, organizing, storing and handling data."

Information models can be defined in an informal way using natural languages such as English, but because a natural language can always be interpreted in different ways, a formal language is preferred, to be as specific as possible. An example of a formal language is the Unified Modeling Language (UML), which is standardized by the Object Management Group (OMG). Two groups are most active in developing standard information models in the IT world: the DMTF with the Common Information Model (CIM), and the TMF with the Shared Information and Data (SID) model. Distinguishing the two approaches is not a simple task. In most cases customers either are not concerned about the models, or they select a model based on the group's history and association. The DMTF has a strong enterprise background as well as a relationship to the storage industry, and the TMF has a strong telecommunications and service provider background.

A liaison has been set up between the TMF and DMTF. The objective is to achieve technology and business model convergence and coordination between SID and CIM.


For more information, consult the following sources:

  • RFC 3444, On the Difference between Information Models and Data Models

  • Directory Enabled Networks by John Strassner (Macmillan Technical Publishing, 1999)

  • Policy-Based Network Management: Solutions for the Next Generation by John Strassner (Morgan Kaufmann, 2003)

Part II: Implementations on the Cisco Devices