COPS specifies a simple client/server model for supporting policy control over quality of service (QoS) signaling protocols (e.g. RSVP).
The Outsourcing Model is the simplest COPS implementation.
Whenever the PEP needs to make a decision, it sends all relevant information to the PDP.
The PDP analyzes the information, makes the decision, and relays it to the PEP.
In the Provisioning Model, see RFC 3084 COPS Usage for Policy Provisioning (COPS-PR), the PEP reports its decision-making capabilities to the PDP.