How do I configure cluster nodes to use a dedicated heartbeat interface?
Red Hat Enterprise Linux Cluster, High Availability, and GFS Deployment Recommended Practices
It is highly recommended to separate the private network for cluster heartbeat from the application network. This should be done wherever possible.
Red Hat Clustering in Red Hat Enterprise Linux 5 and the High Availability Add-On in Red Hat Enterprise Linux 6 use multicasting for cluster membership. If multicasting cannot be enabled in your production network, broadcast may be considered as an alternative in RHEL 5.6+.
Can I use UDP-Unicast (UDPU) in my RHEL High Availability cluster?
UDPU simulates multicast by using UDP unicast to communicate to all the potential cluster members on the network. Since the replication of packets occurs in the OS rather than on the hardware switch the performance may be lower, but in small clusters without much reliance on cluster messaging, this may be a useful alternative to multicast.
Why is UDP unicast (UDPU) not recommended for use in a cluster with GFS2 in a RHEL 6 or 7 Resilient Storage cluster?