As of the Red Hat Enterprise Linux 6.2 release, Red Hat High-Availability Add-On nodes can communicate with each other using the UDP Unicast transport mechanism. It is recommended, however, that you use IP multicasting for the cluster network. UDP unicast is an alternative that can be used when IP multicasting is not available. For GFS2 deployments using UDP unicast is not recommended.

You can configure the Red Hat High-Availability Add-On to use UDP unicast by setting the cman transport="udpu" parameter in the cluster.conf configuration file. You can also specify Unicast from the Network Configuration page of the Conga user interface, as described in Section 3.5.3, “Network Configuration”.