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Abstract

ABSTRACT This paper presents a decentralized, peer-to-peer web cache called Squirrel. The key idea is to enable web browsers on desktop machines to share their local caches, to form an efficient and scalable web cache, without the need for dedicated hardware and the associated administrative cost. We propose and evaluate decentralized web caching algorithms for Squirrel, and discover that it exhibits performance comparable to a centralized web cache in terms of hit ratio, bandwidth usage and latency. It also achieves the benefits of decentralization, such as being scalable, self-organizing and resilient to node failures, while imposing low overhead on the participating nodes. 1. INTRODUCTION Web caching is a widely deployed technique to reduce the latency observed by web browsers, decrease the aggregate bandwidth consumption of an organization's network, and reduce the load incident on web servers on the Internet [5, 11, 22]. Web caches are often deployed on dedicated machines at the boundary of corporate networks, and at Internet service providers. This paper presents an alternative for the former case, in which client desktop machines themselves cooperate in a peer-to-peer fashion to provide the functionality of a web cache. This paper proposes decentralized algorithms for the web caching problem, and evaluates their performance against each other and against a traditional centralized web cache. The key idea in Squirrel is to facilitate mutual sharing of web objects among client nodes. Currently, web browsers on every node maintain a local cache of web objects recently accessed by the browser. Squirrel enables these nodes to export their local caches to other nodes in the corporate network, thus synthesizing a large shared virtual web cache. Each node then performs both web browsing and web caching