The function of a cluster interconnect is different than the traditional use of a network in several ways; therefore, it is useful to think of them as separate technologies. The highest priority use of the cluster interconnects is to carry heartbeat requests and responses.
Heartbeat messages are used to determine the state of the nodes and the cluster interconnects. When a message fails to get through, the cluster software assumes that a failure has occurred and takes action to recover. However, no network is 100 percent reliable, and the PRIMECLUSTER ICF protocol tolerates errors such as lost packets or out of order delivery.
In the cluster interconnects, the physical connections are redundant so that if one fails, one or more remain to carry the messages. However, a sustained outage of all cluster interconnects results in the cluster management software taking action to recover as if a node had failed.
