Characterizing response time of WWW caching proxy servers

Caching proxies have an important role in the infrastructure of the World Wide Web (WWW). They save network traffic and reduce Web latency. While they have been largely deployed in the WWW, little is known about Web proxy behavior, and in particular about international proxies. This paper presents an analysis of caching proxy response times, based on logs from real proxies located in the USA, Europe and South America. We found that high variability is an invariant in caching response times across log data of different proxies. We show that the high variability can be explained through a combination of factors, such as the high variability in the file sizes and bandwidth of the client links to the caching proxies. Finally, we discuss the implications of high variability in the proxy behavior on performance characterization and modeling.