Using trace-driven simulations and measurements, we demonstrate the benefits of Web proxy cache sharing, illustrate the overhead of current cache sharing protocols, and show that the summary cache approach substantially reduces the overhead. Our solution, Bloom filter based summaries with update delay thresholds, has low demand on memory and bandwidth, and yet achieves a hit ratio similar to that of the original ICP protocol. Simulation and analysis further demonstrate the scalability of the protocol. We have built a prototype implementation in Squid 1.1.14.
Much future work remains.
We plan to investigate the impact of the protocol on parent-child proxy cooperations, and the optimal hierarchy configuration for a given workload. We also plan to study the application of summary cache to various Web cache consistency protocols. Last, summary cache can be used in individual proxy implementation to speed up cache lookup, and we will quantify the effect through modifying a proxy implementation.