Storm Control

The Storm Control feature protects a LAN from being affected by unicast, broadcast, or multicast storms that might develop. The switch implements storm control by counting the number of packets of a specified type received within the one-second time interval and compares the measurement with a predefined suppression-level threshold. Storm Control can typically enable the administrator to control traffic by a percentage of total bandwidth or the traffic rate at which packets are received. It is important to note that when the rate of multicast traffic exceeds a set threshold, all incoming traffic (broadcast, multicast, and unicast) is dropped until the level drops below the specified threshold level. Only spanning-tree packets are forwarded in this situation. When broadcast and unicast thresholds are exceeded, traffic is blocked for only the type of traffic that exceeded the threshold.

Storm Control is configured at the interface level with the following command:

storm-control {broadcast multicast unicast} level {level [level-low] pps pps [pps-low]}