Diffserv Policies and Their Combinations in a Policy Server

In policy-based networking, policies sometimes have to be combined and applied in cooperation to represent such programmable and customizable network functions as Diffserv. For a policy server called PolicyXpert, we have designed and implemented three types of policies and three types of virtual flow labels (VFLs) to connect the policy rules. The policy combination enables the representation of complex Diffserv policies. Policy combination also allows sub-classing of DSCP-based service classes, and the separation of service and subscriber policies. The careful design of Diffserv policies has enabled simple Diffserv policies to be represented in a simple form.