200ms Figure 19-3. Rising and falling thresholds The falling threshold is configured after the rising threshold. If no value is entered, the falling threshold is the same as the rising threshold: 3750(config-if)#storm-control broadcast level bps 100 ? <0.0 - 10000000000. [k|m|g] Enter falling threshold Here, I've configured the same thresholds using different forms of the same numbers. Either way is valid: 3750(config-if)#storm-control broadcast level bps 100000 90000 3750 )(config-if)# storm-control broadcast level bps 100m 90k I think the simplest way to configure storm control is with percentages. This is also the only supported method for older versions of IOS: 3750(config-if)#storm-control multicast level 40.5 30 Be careful when configuring multicast storm control. When multicast packets are suppressed, routing protocols that use multicasts will be affected. Control traffic such as Cisco Discovery Protocol (CDP) packets will not be affected, though, and having CDP functioning while routing protocols are not can create confusion in the field during outages. To monitor storm control, use the show storm-control command. The output is not extensive, but you probably won't need to know anything else: 3750#sho storm-control Interface Filter State Upper Lower Current Gi1/0/20 Link Down 1g bps 900m bps 0 bps Gi1/0/21 Link Down 50.00% 40.00% 0.00% Gi1/0/22 Forwarding 1m pps 500k pps 0 pps The Current column shows the current value for the interface. This should be the first place you look if you think you're dropping packets due to storm control. Remember Chapter 19: Catalyst 3750 Features that this is measured every 200 ms, SO you may have to execute the command many times to see whether your traffic is spiking. You can also run the command for specific storm-control types (broadcast, multi cast, or unicast). The output is the same but includes only the type specified: 3750#sho storm-control unicast Interface Filter State Upper Lower Current Gi1/0/19 Link Down 50.00% 40.00% 0.00% Finally, you can specify a particula