Storm control
A switch feature that monitors the amount of broadcast, multicast, or unknown-unicast traffic on a port and starts dropping it if it exceeds a threshold. It protects the network against broadcast storms — often caused by a loop or a broken device.
Problem: a broadcast storm (e.g. from a switch loop that STP didn't stop in time, or a faulty NIC spewing broadcasts) can in seconds saturate links and CPUs and paralyze an entire network. Storm control sets a limit (as a percentage of bandwidth or packets per second) per traffic type and port; if it's exceeded the excess is suppressed (dropped), and the port can optionally be shut down (err-disable) or alarm. Win: it limits the damage of a storm to the affected port instead of the whole network going down. A complement to STP/loop protection (STP prevents loops, storm control limits the consequences if something fails anyway). Standard on access ports in robust networks, together with BPDU guard and port security. Related to broadcast domain and BPDU guard.