The figure shows requests going through a load balancer and into only the I2 instance. Instance I1 is stopped and removed from Cluster1. Cluster1 is now empty. Instance I2 is still in Cluster2.
Each instance contains an OC4J instance called OC4J_Clustered. Instance I1 contains version 0 of the "App" application, while instance I2 runs version 1 of the same application.
The two OC4J_Clustered instances are still in the same IP multicast replication group, but because I1 is not running, HttpSession replication is not taking place.