An iSeries™ cluster is a collection of one or more servers or logical partitions that work together. Servers in a cluster, called cluster nodes, work cooperatively to provide a single computing solution. Communication between cluster nodes is based on TCP/IP protocols. OptiConnect software can be used to provide this communication between cluster nodes. The major cluster communication functions supported by OptiConnect include cluster heartbeat, application IP takeover, and device IP takeover. For more information, see the Clusters topic.