Content-based load balancing with multicast and TCP-handoff

Recently, cluster systems have been used by many web sites to increase service availability and balancing workload among multiple servers. There are two types of cluster architecture; centralized cluster and distributed cluster. Although centralized cluster is more effective at load balancing than distributed cluster, it contains two serious weaknesses; bottlenecking and single-point-of-failure. To achieve the strengths of both the centralized and distributed clusters, this paper proposes the use of distributed cluster using multicast technology. With the use of distributed cluster, problems of bottleneck and single-point-of-failure are effectively prevented. To gain the load balancing strength of centralized cluster, multicast technology is employed. Multicast load balancing occurs at layer-2 of the protocol stack. Hence, the overhead of request redirecting is significantly reduced. Additionally, TCP-handoff technology for content-based load balancing is applied to enhance system's availability and scalability.