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DEN (Directory Enabled Networks)

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Note: Many topics at this site are reduced versions of the text in "The Encyclopedia of Networking and Telecommunications." Search results will not be as extensive as a search of the book's CD-ROM.

DEN is a network management specification that integrates policy services and directory services in a way that provides configuration and policy-based access control to network resources- specifically, network bandwidth. According to the DEN specification, "directories must be transformed from a dumb warehouse to an authoritative, distributed, intelligent repository of information for services and applications." Some advocate that the directory service is now the heart of the network, the place where all network operations are defined and managed.

DEN defines a standard directory services architecture and schema that can be used to store network policy and configuration information. It is a blueprint that attempts to guarantee interoperability among vendors of network equipment, directory services, and applications. DEN's primary components include a distributed database, a consistent data model, and LDAP (Lightweight Directory Access Protocol). The distributed database can be replicated to other locations. The data model defines the structure of the data-that is, how real-world objects are defined in the directory. LDAP is a protocol that applications use to access the directory.

Microsoft first proposed the architecture and did early work with Cisco. Eventually, DEN was transferred to the DMTF (Desktop Management Task Force) to help promote its widespread standardization. The DMTF completed the initial specification in 1998, and has since expanded it. The IETF Policy Framework (policy) Working Group is working to define how policies and policy information is implemented in network environments. It is defining an extensible information model and schemata to represent policy. It is also addressing policy as it relates to QoS traffic management and Differentiated Services (Diff-Serv).

This topic continues in "The Encyclopedia of Networking and Telecommunications" with a discussion of the following:

  • DENs role in organizing and manageing networks
  • DENs role in bandwidth management
  • Standard scheme and the DMTF's CIM (Common Information Model)
  • DEN directory scheme and information model (illustration and discussion)

An interesting RFC that discusses developments in directories, policies, resource management, and QoS is RFC 2768 (A Report of a Workshop on Middleware, February 2000).

Copyright (c) 2001 Tom Sheldon and Big Sur Multimedia.
All rights reserved under Pan American and International copyright conventions.