document: Hierarchical substring caching for efficient content distribution to low-bandwidth clients While overall bandwidth in the internet has grown rapidly over the last few years , and an increasing number of clients enjoy broadband connectivity , many others still access the internet over much slower dialup or wireless links . To address this issue , a number of techniques for optimized delivery of web and multimedia content over slow links have been proposed , including protocol optimizations , caching , compression , and multimedia transcoding , and several large ISPs have recently begun to widely promote dialup acceleration services based on such techniques . A recent paper by Rhea , Liang , and Brewer proposed an elegant technique called value-based caching that caches substrings of files , rather than entire files , and thus avoids repeated transmission of substrings common to several pages or page versions . We propose and study a hierarchical substring caching technique that provides significant savings over this basic approach . We describe several additional techniques for minimizing overheads and perform an evaluation on a large set of real web access traces that we collected . In the second part of our work , we compare our approach to a widely studied alternative approach based on delta compression , and show how to integrate the two for best overall performance . The studied techniques are typically employed in a client-proxy environment , with each proxy serving a large number of clients , and an important aspect is how to conserve resources on the proxy while exploiting the significant memory and CPU power available on current clients .
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