Extreme Networks sees the directory as a way for policy servers to share information, allowing scalability and third-party interoperability. Lucent sees the directory as a giant storehouse of information, where each user has a private subtree. For Lucent, the directory is the single sign-on for complete network resource management, both voice and data services. The vendor plans to accomplish this via a directory-independent LDAP schema. There are other roles for policy-based network management as well.
Conditions are events that cause a certain policy to take effect.
Actions define what is done when a condition is met, while roles define how a device or interface implements an action. Policy conditions can be defined at almost any layer of the OSI model, a communications standard that defines a framework for implementing protocols in seven layers. The amount of functionality is limited only by the software implementation and the capability of the hardware. Most vendors concentrate their software on the IP layer and above. Notable exceptions are Extreme, HP, Nortel, and Spectrum.