Analysis and Design of Routing Based Hierarchical Internet Cache Protocol Architecture

Abstract

The rapid growth of the WWW has caused the Internet traffic serious congestion in recent years. Proxy cache is a good technology to solve this problem by distributing web server file objects. However, standing alone proxy cache often suffers from low hit ratio due to huge WWW cache working set size. Internet Cache protocol (ICP) was used to construct cooperative proxy caching architectures to increase the Internet cache hit ratio or make a load balance between cooperative proxies to share requests of large scale clients. However, ICP especially hierarchical cache architecture has the disadvantage of poor response time due to extra network communications when the parent cache misses occur. In fact, if the hit rate of the parent cache is high, and this parent cache is on the nearby routing path 1of the children proxies to the Web server sites, extra network traffic will be minimized. It will decrease the clients’ response time surely. We demonstrate our viewpoint that the importance of parent cache is on the nearby routing path of the child cache to the Web server sites by showing a simple formula and analyzing proxy server log of MHIT (Ming-Hsin Institute of Technology). We construct a mathematical model to describe some hierarchical Internet cache behaviors. These Internet cache behaviors are “reverse lookup” and “reverse cache effect”, which are described in this article. Furthermore, we develop a methodology to evaluate the cache time of the selected parent cache and analyze the proxy cache log to estimate the routing effect on the cache time of our simulated proxy servers. Evaluation shows that routing factor, whether the proxy server is on the near routing path of the child cache to the Web server sites or not, is more much subtle to the hit time than the miss time of the parent cache. The miss time of the parent cache is dependent on the relationship between the web distribution and the routing position of this proxy server.