Generally, any of the AAA Servers (or Access Control Engines) transactions may retrieve a policy or evaluate a Access Control Policy, and any of the Service Equipment may enforce a policy. Policy Retrieval Points (Policy Repositories) may reside on any of the Access Control Engines or be located elsewhere in the network.
Data against which Access Control Policy conditions are evaluated (such as resource status, session state, or time of day) are accessible at Policy Information Points (PIPs) and might be accessed using Policy Information Blocks (PIBs).
A Policy Based Management System consists of four main functional Non_normative elements: (following RFC 2904, except for PAP) [2]
ABBR | Term | Description |
---|---|---|
PAP | Policy Administration Point | Point which manages access authorization policies |
PDP | Policy Decision Point | Point which evaluates access requests against authorization policies before issuing access decisions |
PEP | Policy Enforcement Point | Point which intercepts user's access request to a resource, makes a decision request to the PDP to obtain the access decision (i.e. access to the resource is approved or rejected), and acts on the received decision |
PIP | Policy Information Point | The system entity that acts as a source of attribute values (i.e. a resource, subject, environment) |
PRP | Policy Retrieval Point | Point where the XACML access authorization policies are stored, typically a database or the filesystem. (Not in DIagram below) |
Policy sets, rules and requests all use subjects, resources, environments, and Resource Action.
The Resulting policies are stored in a Policy Retrieval Point
When new policies have been added in the Policy Retrieval Point, or existing ones have been changed, the Policy Administration Point MUST update the relevant Policy Retrieval Points
When an actionable event is encountered at the Policy Enforcement Point contacts the Policy Decision Point which interprets the policies from the Policy Retrieval Points and the Policy Information Point and then communicates the appropriate decision to be exercised by the Policy Enforcement Point
The most well known policy-based management architecture was specified jointly by the IETF and the DMTF. This consists of four main functional elements:[1]