Policy based Management of Content Distribution Networks

We present a policy-based architecture for the control and management of content distribution networks that form an overlay of caching proxies over an underlying physical network. The architecture extends the policy framework used for controlling network Quality of Service (QoS) and security to the case of content distribution networks. The fundamental advantage of a policy-based framework is that it allows a machine-independent scheme for managing multiple devices from a single point of control. In this paper, we describe this architecture and demonstrate how it enables dynamic updates to content distribution policies. Furthermore, we analyze the impact of such dynamic distribution on the cost of content serving. I. INTRODUCTION Ensuring a satisfactory performance level for web-based applications on the Internet is a long-standing problem within the networking research community. In order to address the performance issues, several approaches have been developed. The three most prominent approaches to managing the performance of applications include the IntServ/RSVP [1] signaling approach, the DiffServ approach [2] and the content distribution approach [3] [4]. The IntServ approach is based on the notion of reserving resources within the network, the DiffServ approach is based on the notion of mapping traffic aggregates into several different service classes, and the content distribution approach is based upon deploying a number of proxy servers scattered within the network that use a variety of caching techniques to improve the response time of web-based applications. While each approach has its own advantages and disadvantages, they all share one common problem. The proper operation of each approach requires a consistent configuration of a large number of widely distributed devices. The policy based management paradigm, which has recently gained prominence, provides mechanisms that can be used to address this problem. Policy based techniques are being developed for the Integrated Services and the Differentiated Services technologies by various working groups within the IETF [5]. In this paper, we explore the methods by which the same technical approach can be applied to a content