The IMS: IP Multimedia Concepts And Services, Second Edition

21.3. COPS usage for policy provisioning (COPS-PR)

COPS-PR defines COPS usage for policy provisioning and is independent of the provisioned policy. The PEP describes its configurable parameters in policy requests, denoted as configuration requests. If there is a change in these parameters, an update request is sent. The requests do not necessarily map directly to any decisions, which are typically issued by the PDP only when the PDP responds to external events: for example, the PDP would issue a configuration decision only when a Service Level Agreement (SLA) is changed. Hence, both policy requests and decisions may be fairly infrequent.

The data model in COPS-PR is based on something called a Policy Information Base (PIB). Policy-provisioning data are identified by a PIB, and each area of policy provisioning may have one or more PIBs defined. In other words, a given PEP–PDP connection may see multiple PIBs in transit, but each PIB would be associated with a specific client type.

As the name suggests, it is quite similar to the Management Information Base (MIB) [RFC3418]used for the Simple Network Management Protocol (SNMP) [RFC3411]. In fact, they share a common data structure, as both use Structure for Management Information Version 2 (SMIv2) definitions. In COPS-PR this is used for Encoded Provisioning Instance Data (EPID) encoding rules.

The policy data are conceptually structured as a tree, with the PIB being the root. As such a PIB represents a virtual database for the contents ...