When the Squirrel peer-to-peer web caching service was evaluated by simulation, 4.11 hops were required on average to route a request for a cache entry when simulating the Redmond traffic, whereas only 1.8 were required for the Cambridge traffic. Explain this and show that it supports the theoretical performance claimed for Pastry.

An external caching scheme stores copies of web objects

or meta-data so that clients can avoid requests to a web

server. The best known example of an external cache is a

web proxy, but with the rapid spread of web technologies,

many other caching scenarios can be identified. Caching

is central to performance in the web, both because it re-

duces load on servers, and because cached data is normally

cheaper to access from another machine that is closer in the

network. Although cooperation between cache managers is

not a common feature of existing web architectures, coop-

erative caching supported by peer-to-peer architectures has

great potential [9, 13]. When sets of client systems have sim-

ilar interests and fast low-latency interconnections, shared

caching could bring significant benefits.

The peer-to-peer mechanisms referred to

Explanation: