||For the past few years, WWW (World Wide Web) traffic has been tremendously growing on the Internet. However, it ironically becomes “World Wide Wait” due to overloaded server and/or seriously congested network. Almost any computer system that suffers from latency or bandwidth problems can benefit from caching. The introduction of cache concept to WWW server certainly reduce the waiting time at clients by efficiently relieving both the server and network load.|
The purpose of this thesis is to design a hierarchical cache system so that it can work efficiently. The cache servers being used today have encountered the problems of lack of efficient collaboration due to different configuration flavors of management. In other words, the highest level of a hierarchical cache system may easily become the bottleneck, which in turn slow down the entire cache system. In our cache design, we apply inclusive and exclusive relationship to modify the ICP (Internet Cache Protocol) and use the recursive concept to build a hierarchical architecture to avoid the un-necessary information query. This implies that the lowest level can fetch the data from the destination server directly and perform the update recursively to its upper level. The up-side-down traffic flow, reffered to as reverse traffic flow in this thesis, can substantially release the load of upper levels in the hierarchy.
For the purpose of performance evaluation, we derive a general mathematical equation by analyzing the operation procedures step by step. The analytical results have shown that the highest level within this hierarchy can reduce almost 50% of the load under the worst-case assumption. Although the lower levels may slightly increase their work load, it does significantly increase the overall WWW efficiency and avoid the potential bottlenecks by balancing the loads among different levels.