  Traditional load balancers used in server clusters have problems such as lack
of flexibility, high cost, etc. To overcome these problems, research has been
conducted to apply a load balancer using software-defined network (SDN) to the
server cluster. Under this trend, in this paper, we proposed a hybrid load
balancing method with failover capability in the server cluster using SDN. The
main goal of this paper is to improve the performance and failover capability
of load balancing. First, we improved the performance of the dynamic weighted
random selection (DWRS) algorithm by adopting the binary search to find the
target server. Next, we proposed a dynamic method with failover capability by
combining the improved DWRS algorithm with a fast-failover (FF) group table. In
addition, a hybrid method combining the static method using the SELECT group
table and the dynamic method with failover capability is proposed to improve
the performance. Finally, the failover capability and performance of the
proposed method are evaluated in an experimental environment.
