Peer-to-peer Web caching: hype or reality?

In this paper, we systematically examine the design space of peer-to-peer Web caching systems in three orthogonal dimensions: the caching algorithm, the document lookup algorithm, and the peer granularity. Based on the observation that the traditional URL-based caching algorithm suffers considerably from the fact of cacheability decrease caused by the fast growing of dynamic and personalized Web content, we propose to use the content-based caching algorithm. In addition to compare two existing document lookup algorithms, we propose a simple and effective geographic-based document lookup algorithm. Four different peer granularities, i.e., host level, organization level, building level, and centralized, are studied and evaluated using a seven-day Web trace collected at a medium-size education institution. Using a trace-driven simulation, we compared and evaluated all design choices in terms of two-performance metrics: hit ratio and latency reduction. Finally, several implications derived from the analysis are also discussed.