Scalable Delivery of Web Pages Using Cyclic Best-Effort (UDP) Multicast

Abstract

The World Wide Web (WWW) has gained tremendously in popularity over the last several years. Solutions to the problem of overloaded web servers have included buying more hardware, the use of transparent server replication and mirroring, and caching of hot pages. Another technique that can be used in conjunction with these other solutions is the use of multicast for the delivery of web pages. In this work we explore the use of UDP, best-effort multicast as a delivery option. Reliability is achieved through repetitive, cyclic transmission of a requested page. This solution is expected to be most efficient when used for highly requested pages. We view this cyclic multicast technique as a delivery option that can be integrated with the traditional reliable unicast and recently proposed reliable multicast options. We first describe the architecture of an integrated web server employing all three delivery options. We then describe the cyclic multicast technique and consider the various procedures needed for its successful operation. We characterize the gains in performance achieved by our proposal through an extensive performance analysis and simulation of our technique by itself, and when integrated with the other delivery options. We also describe our experience with an implementation of a prototype cyclic multicast server and its performance over the Multicast Backbone (MBone).