Transparent En-Route Caching in WANs?

Hierarchical caching is being widely used today to improve web performance. The way hierarchical caches are deployed requires clients and caches to be aware of the location of nearby caches. This creates management and connguration issues, and may also lead to performance bottlenecks. In contrast, Transparent en-route caches (TERC) are devices that are placed at appropriate locations within the network and work obliviously. A TERC intercepts web requests and web data. If the requested item exists in the TERC's memory, the data is sent to the requester, otherwise the request is transparently forwarded up the routing path. TERCs have the potential to be more eecient than plain proxy caches. In reducing latency, they provide the twin beneets of improving latency through cache hits and not introducing additional delay in rerouting requests from one cache to another. TERCs can also be deployed in a subnet without any cooperation from clients or the providers, and since they see all the web traac, their eeectiveness is enhanced. Deploying TERCs in LANs and WANs pose diierent issues. In this paper, we discuss issues like deployment and implementation, cache location, and hit rate variation, in evaluating a case for TERCs in WANs. We conclude that TERCs in WANs are a promising technique.

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