COPS Policy Provisioning
A policy enforcement point (PEP) requests a policy decision from the policy decision point (PDP) using COPS. However, nowhere in COPS is there a means to establish the basis for making the policy decisions. That is, the PEP describes its configurable parameters in a configuration request, and the PDP issues the appropriate configuration. When these parameters change, an update request is sent and another policy decision is returned. Since these requests only occur when things like service levels change, they are infrequent.
In the COPS Policy Provisioning (COPS-PR) model, the policy provisioning data is stored in a policy information base (PIB). Each policy provisioning area can have one or more PIBs defined. While a PEP/PDP pair might see multiple PIBs in transit, each PIB is related to a specific client type. As the name suggests, the PIB is similar in form and function to the management information base (MIB) used with the Simple Network Management Protocol (SNMP).
The data structure for the PIB is a tree, and thus the PIB itself can be considered a virtual database for the tree contents. Sub-trees (branches) are called provisioning classes (PRC), and leaves are called provisioning instances (PRI). Like the botanical tree, there can be numerous branches (PRCs) on a tree and numerous leaves (PRIs) per branch. The provisioning instance identifier (PRID) is the name carried in the COPS object. The 3GPP has defined a PIB for the Go interface between the GGSN (client) and the PDF (server).