We needed a framework for studying tradeoffs and impact of different parameters on a web server system, this framework was required to test performance of Distributed Web Server System proposed by us and compare its performance with other architectures proposed earlier e.g., round robin, random, weighted etc.
To compare various policies for request distribution at server side, we designed and implemented a test bed which tries to emulate real network scenarios and follows all steps in HTTP request service. In fact, all standard components used in the Internet are used in this test bed, for example, BIND (Berkeley Internet Domain Name Server) is used for DNS and Apache web servers. We have used Webstone [30] for generating HTTP requests. We have modeled WAN delays and bursty packet losses which are common on Internet links. All machines used are Pentium PCs running Linux operating System.
In this chapter, we first describe design goals, and then discuss our assumptions. After a brief overview of the test bed, we describe request distribution mechanisms used at the front node and DNS. Lastly we describe various components of the test bed.