The figure shows requests going through a load balancer and into two Oracle Application Server instances (I1 and I2) in a cluster, Cluster1. Each instance contains an OC4J instance called OC4J_Clustered. Version 0 of an application called "App" is running in OC4J_Clustered. HttpSession replication is going on between the two OC4J_Clustered instances because the instances are in the same IP multicast replication group.