ip multicast group upnp drop

UPnP traffic is not blocked. Like any protocol packets, multicast protocol packets are forwarded by the switches. The switches do not drop any multicast packets. On most switches, multicast and broadcast hit the CPU of the switch, causing the CPU to spike or to be over utilized. When the CPU is spiked, latency, protocol flaps, and so on, can occur. Although UPnP is supposed to be exclusively used for small home networks, it is turned on by default on most Microsoft devices. By default, UPnPs are not blocked by ICX devices. However, if too many clients running UPnP are present on the network, a CPU spike can occur, causing network latency and protocol flaps.