Overview#
Common Open Policy Service Protocol (
COPS) is part of the
Internet Protocol Suite as defined by the
IETF's
RFC 2748.
COPS specifies a simple client/server model for supporting policy control over Quality of Service (QoS) signaling protocols (e.g. RSVP). Policies are stored on servers (PIPs), and acted upon by Policy Decision Points (PDP), and are enforced on clients, also known as Policy Enforcement Points (PEP).
TWO Common Open Policy Service Models#
There are two models of
COPS:
The Outsourcing Model and the Provisioning Model, considered from the view of the client or PEP.
Outsourcing Model#
The Outsourcing Model is the simplest
COPS implementation. In this model, all policies are stored at the
PDP. 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. The
PEP then simply enforces the decision.
Provisioning Model#
In the Provisioning Model, see
RFC 3084 COPS Usage for Policy Provisioning (
COPS-PR), the
PEP reports its decision-making capabilities to the
PDP. The
PDP then downloads relevant
policies on to the
PEP. The
PEP can then make its own decisions based on these policies. The Provisioning Model uses the Policy Information Base as a repository of the policies.
Common Open Policy Service is a Policy Based Management System
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