Policy Control

Policy control is a variation of network management. It recognizes that when configuration requests arrive through signaling protocols rather than through management protocols, each network node is responsible for applying some policy to decide how to treat the requests. This policy may be local (specific to the node making the decision) or applicable across a wider domain, and the decision can be made at each node or devolved to centralized policy servers.

Note that when devices are managed through a management protocol there is still a policy that governs what resources can be provisioned in support of which services, but that policy is usually applied by the network operator in consultation with a management application.

The IETF defined a framework for policy control in RFC 2753 and the Common Open Policy Service (COPS) protocol to convey policy requests between clients and servers in RFC 2748. Since then, it has been recognized that policy requests and responses, and also policy pushes, are simple client/server data transfers similar to file transfers, and the rather complicated COPS protocol has been largely abandoned in favor of transferring XML-encoded policy information using SOAP (see previous discussion) or the Blocks Extensible Exchange Protocol (BEEP).