esaProbeSLMMulticastMACEnabled is a read-create true/false flag, valid only for SLM-SLR probes, controlling whether the probe addresses its Synthetic Loss Measurement messages to a multicast MAC address. An administrator toggles this depending on whether the network segment expects unicast or multicast SLM frames to reach the reflector correctly. For example, enabling multicast addressing on an SLM-SLR probe lets a single test reach a reflector that only listens for multicast-addressed loss-measurement frames, where a unicast-addressed probe would simply be ignored.