ClusterXL provides reliability through High Availability and increases performance through Load Sharing.
ClusterXL Load Sharing uses Multicast and Unicast mode. In Multicast mode, every cluster member receives every packet. Cluster members then run decision functions, and come to the same conclusion for one member to handle a packet. In Unicast mode, only the pivot machine receives all packets and determines which member should handle the packet, and forward it to the appropriate member.
ClusterXL High Availability uses New and Legacy mode. New mode High Availability cluster members have unique IP addresses and share virtual IP addresses. Legacy mode is not recommended for NG with Application Intelligence.