Multi-Level Load Balancing Methods for Hierarchical Web Server Clusters

With the need for scalability on web servers due to various demands of users and an explosive growth of the Internet users, researchers had addressed how to make well clusters of many web servers in past. In this paper, we propose a hierarchical clustering method of web servers to cover limits of single-level web server with high scalability and availability. Underlying structures of the hierarchical web server clustering are load balancers and real servers at the bottom level. The load balancer is attached on the top level basically and it can be extendable to n-levels of structure. The proposed algorithm dealing with dynamic weights based on agents at the bottom level shows faster response time compared to the existing round-robin and least connection algorithms. It is also possible to apply different algorithms for each level, and we evaluate that the proposed algorithm could reduce the workload imbalance among the real servers.