Which ClusterXL mode utilizes a non-unicast MAC address for the cluster IP address?

In ClusterXL, the mode that utilizes a non-unicast MAC address for the cluster IP address is Load Sharing Multicast. This mode is designed specifically to handle multiple active gateways within a cluster while ensuring that traffic is distributed across them effectively.

When using Load Sharing Multicast, the cluster appears as a single entity to clients, but it employs a multicast MAC address that allows for more efficient use of network bandwidth and helps to achieve optimal load balancing. With a non-unicast MAC address, packets destined for the cluster IP can be sent to all active members of the cluster, enabling them to process the traffic, thus improving redundancy and performance.

In contrast, High Availability and Master/Backup modes use a unicast MAC address where one member acts as the primary gateway and the other as a backup, failing over only when the primary becomes unavailable. Load Sharing Pivot also employs a unicast addressing mechanism, where there's a designated pivot point in the cluster. Therefore, Load Sharing Multicast is distinct in its ability to utilize a non-unicast MAC address, enhancing the efficiency of traffic distribution among active cluster members.