3.11. Multicast Addresses

The nodes in a cluster communicate among each other using multicast addresses. Therefore, each network switch and associated networking equipment in the Red Hat High Availability Add-On must be configured to enable multicast addresses and support IGMP (Internet Group Management Protocol). Ensure that each network switch and associated networking equipment in the Red Hat High Availability Add-On are capable of supporting multicast addresses and IGMP; if they are, ensure that multicast addressing and IGMP are enabled. Without multicast and IGMP, not all nodes can participate in a cluster, causing the cluster to fail; use UDP unicast in these environments, as described in Section 3.12, “UDP Unicast Traffic”.

Note

Procedures for configuring network switches and associated networking equipment vary according each product. Refer to the appropriate vendor documentation or other information about configuring network switches and associated networking equipment to enable multicast addresses and IGMP.