QoS differentiation in switching-based Web caching

Differentiated services (DiffServ) [1998] are being adopted for various Internet applications, including Web services. In the Web-caching field, researchers have proposed to realize DiffServ on Web servers, cache servers, and the client. We argue that there are significant advantages of implementing DiffServ on edge routers in a distributed Web caching system. Edge routers can perform request classification, and assign the type of service, hence the per-hop behavior of the classified requests. If the edge router has knowledge of each cache server, then the edge router is able to provide quality of service to different requests by forwarding the requests to the most appropriate cache server. We propose a switching-based differentiated service aching scheme that provides different types of service to three classes of requests, namely streaming class, real-time assured class and best-effort class. A detailed simulation model is described and then used to examine the conditions under which our scheme is able to satisfy the service requirements of the three classes.