Web Caching, Consistency, and Content Distribution

Caching has been widely deployed to improve Web performance by reducing client-observed latency and network bandwidth usage in addition to improving server scalability by reducing the load on the servers. Web caches can be deployed at various points in the network. Forward proxy caches are deployed close to the client at network entry points by ISPs to reduce the network bandwidth usage and improve client latency by caching frequently accessed data. Such caches can be either
transparent to the client or be manually configured. With transparent caching the packets are intercepted by an intermediate router (layer 4 or layer 7 switch) and transparently routed to a cache which in turn responds to the client directly [cis]. Manual configuration requires the client to explicitly configure the browser to go via a proxy cache. In addition to forward proxies, caches can be deployed as a front-end to a server farm to reduce server load and increase server scalability. Such caches called reverse proxies are useful in eliminating the load of a hot-set from impacting the server performance. Typically reverse proxies are in the same administrative domain as the server.

By: Arun K. Iyengar, Erich M. Nahum, Anees A. Shaikh, Renu Tewari

Published in: RC22845 in 2003


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