Policy evaluation for network management

Policies are increasingly being used to manage complex communication networks. In this paper we present our work on a “policy server” which is being used to provide centralized administration of packet voice gateways and “soft switches” in next generation circuit and packet telephony networks. The policies running in the policy server are specified using a domain independent policy description language (PDL). This paper is motivated by the problem of evaluating policies specified in PDL. We present an algorithm for evaluating policies and study both its theoretical and empirical behavior. We show that the problem of evaluating policies is quite intractable. However we note that the hard instances of the policy evaluation problem are quite rare in real world networks. Under some very realistic assumptions we are able to show that our policy evaluation algorithm is quite efficient and is well suited for enforcing policies in complex networks. These results constitute the first attempt to develop a formal framework to study the informal concepts of policy based network management