C-14
Cisco 3200 Series Router Hardware Reference
OL-5816-10
Appendix C Switch Port Functionality
Storm Control
when a threshold for one type of traffic is reached, that type of traffic is dropped. This threshold is
specified as a percentage of the total available bandwidth that can be used by broadcast (multicast or
unicast) traffic.
The combination of broadcast suppression threshold numbers and the 1-second time interval control the
way the suppression algorithm works. A higher threshold allows more packets to pass through. A
threshold value of 100 percent means that no limit is placed on the traffic.
Note Because packets do not arrive at uniform intervals, the 1-second time interval during which traffic
activity is measured can affect the behavior of storm control.
The switch continues to monitor traffic on the port. When the utilization level falls back below the
threshold level, the type of traffic that was dropped is forwarded again.
Use the storm-control broadcast, storm-control multicast, and storm-control unicast global
configuration commands to set up the storm control threshold value.
Storm Control Configuration
This section describes how to configure storm control on your router. It consists of the following
configuration information and procedures:
• Enabling Storm Control
• Verifying Storm Control
By default, unicast, broadcast, and multicast suppression is disabled on the switch.

Enabling Storm Control

Enable storm-control globally and enter the percentage of total available bandwidth that you want to be
used by a all traffic (multicast, unitcast,); entering 100 percent would allow all traffic.
To enable a particular type of storm-control, use the following commands beginning in privileged EXEC
mode:
Command Purpose
Step 1 Router# configure terminal Enters global configuration mode.
Step 2 Router(config)# [no] storm-control
broadcast threshold
<0
-
100>
Specifies the broadcast suppression level for an interface as a
percentage of total bandwidth. A threshold value of 100 percent
means that no limit is placed on broadcast traffic.
Use the no keyword to restore the defaults.
Step 3 Router(config)# [no] storm-control
multicast threshold
<0
-
100>
Specifies the multicast suppression level for an interface as a
percentage of total bandwidth.
Use the no keyword to restore the defaults.
Step 4 Router(config)# [no] storm-control
unicast threshold
<0
-
100>
Specifies the unicast suppression level for an interface as a
percentage of total bandwidth.
Use the no keyword to restore the defaults.
Step 5 Router(config)# end Returns to privileged EXEC mode.