Multicast-Based Distributed LVS (MD-LVS) for Improving Scalability and Availability

Clustering with a single -system image view is the most commonly used approach to increase throughput of a Web site. There are two types of clustering architecture: centralized IP cluster and distributed IP cluster. In centralized IP cluster, Load Balancer distributes incoming requests of clients to an appropriate Real Server based on load characteristics. However, the availability and scalability of cluster system is low, since this kind of solution creates a single-point-of-failure and the total throughput of cluster is limited by the performance of Load Balancer. In distributed IP cluster, every host in a web server cluster acts both as a Load Balancer and as a real server. However, this approach may increase the CPU workload of all the hosts to process the packetfiltering and load balancing. In this paper, we propose the Multicast-based Distributed LVS (MD-LVS), which combines centralized IP 2 cluster and distributed IP cluster. There are multiple Load Balancers and each Load Balancer has an individual and independent cluster group, which consists of several real servers. This mechanism efficiently can improve scalability and availability of cluster system, since it is easy to expand the cluster system and may avoid the entire system failure.