Which Proxy

A simple solution to the proxy selection question is to pick a proxy that is nearest to the proxy where cache miss happens. Since this is a ``local'' decision within the ISP's backbone, it is easy to implement in practice. An alternative is to choose those proxies that are nearer to the client such that user perceived latency could also be reduced. However, depending on the environment, it is likely difficult to obtain clients' geographical location information.

In summary, forwarding requests can reduce backbone bandwidth consumption, but it may possibily increase client latency as well. The tradeoff between bandwidth and latency is the major factor affecting the policies.

Although our mechanism is targeted at reducing backbone bandwidth for populating the caches, it can also be applied in other situations, such as proxy overload or network congestion. However, how to coordinate proxies to obtain other benefits is not covered in this paper.