A critical network failure state that occurs when the number of active multicast groups exceeds the hardware capacity of a network switch's multicast forwarding table. In entertainment lighting networks utilizing Streaming ACN (sACN or ANSI E1.31), each control universe is mapped to a unique multicast IP address within the 239.255.0.0 to 239.255.255.255 range. Managed switches use IGMP snooping to listen to subscription requests and deliver sACN data only to the specific physical ports that require it. However, if a massive production uses more sACN universes than the switch's table can track, the switch experiences IGMP exhaustion. When this table overflows, the switch typically reverts to treating all multicast traffic as broadcast, flooding every single port with all sACN universe data. This sudden flood of traffic causes severe network congestion, packet loss, and visible fixture flickering on the rig. Proactive network monitoring systems like QubiSet help technicians detect high multicast group counts and manage overall network load to prevent these failures before they can disrupt a live show.