Per its description, this CienaGlobalState object turns on or off the trap pair signaling that multicast traffic on the dataplane has exceeded, and later returned below, a configured threshold. Multicast load spikes are typically tied to IPTV, video conferencing, or replication storms, so this trap lets an operator distinguish a multicast-driven congestion event from the separate unicast and broadcast threshold traps on the same box. A service provider carrying multicast video would enable this to catch a channel-change storm or a misconfigured IGMP join flood before it saturates a trunk.