Jul
30
Cisco storm control again
This document provides an overview of Cisco’s Storm Control including configuration steps and examples as well as implications of using storm control.
The purpose of storm control is to prevent a packet storm from over-utilizing the resources of a switch. By default storm control is not configured and must be enabled on a per-interface basis. There are three types of storm control; unicast, multicast, and broadcast, and they are all configured separately using the following options, taken from Cisco’s website;
Command
Purpose
Step1
configure terminal
Enter global configuration mode.
Step2
interface interface-id
Specify the interface to be configured, and enter interface configuration mode.
Step3
storm-control {broadcast | multicast | unicast} level {level [level-low] | bps bps [bps-low] | pps pps [pps-low]}
Configure broadcast, multicast, or unicast storm control. By default, storm control is disabled.
The keywords have these meanings:
• For level, specify the rising threshold level for broadcast, multicast, or unicast traffic as a percentage (up to two decimal places) of the bandwidth. The port blocks traffic when the rising threshold is reached. The range is 0.00 to 100.00.
• (Optional) For level-low, specify the falling threshold level as a percentage (up to two decimal places) of the bandwidth. This value must be less than or equal to the rising suppression value. The port forwards traffic when traffic drops below this level. If you do not configure a falling suppression level, it is set to the rising suppression level. The range is 0.00 to 100.00.
If you set the threshold to the maximum value (100 percent), no limit is placed on the traffic. If you set the threshold to 0.0, all broadcast, multicast, and unicast traffic on that port is blocked.
• For bps bps, specify the rising threshold level for broadcast, multicast, or unicast traffic in bits per second (up to one decimal place). The port blocks traffic when the rising threshold is reached. The range is 0.0 to 10000000000.0.
• (Optional) For bps-low, specify the falling threshold level in bits per second (up to one decimal place). It can be less than or equal to the rising threshold level. The port forwards traffic when traffic drops below this level. The range is 0.0 to 10000000000.0.
• For pps pps, specify the rising threshold level for broadcast, multicast, or unicast traffic in packets per second (up to one decimal place). The port blocks traffic when the rising threshold is reached. The range is 0.0 to 10000000000.0.
• (Optional) For pps-low, specify the falling threshold level in packets per second (up to one decimal place). It can be less than or equal to the rising threshold level. The port forwards traffic when traffic drops below this level. The range is 0.0 to 10000000000.0.
For BPS and PPS settings, you can use metric suffixes such as k, m, and g for large number thresholds.
Step4
storm-control action {shutdown | trap}
Specify the action to be taken when a storm is detected. The default is to filter out the traffic and not to send traps.
• Select the shutdown keyword to error-disable the port during a storm.
• Select the trap keyword to generate an SNMP trap when a storm is detected.
Step5
end
Return to privileged EXEC mode.
Step6
show storm-control [interface-id] [broadcast | multicast | unicast]
Verify the storm control suppression levels set on the interface for the specified traffic type. If you do not enter a traffic type, broadcast storm control settings are displayed.
Step7
copy running-config startup-config
(Optional) Save your entries in the configuration file.
To disable storm control, use the
no storm-control {broadcast | multicast | unicast} level interface configuration command.
For configuration, use the following commands;
Switch# configure terminal
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# storm-control unicast level pps 60k 50k
This configuration would stop forwarding packets when the traffic on the interface reached 60k packets per second, and would not begin forwarding packets again until it dropped below 50k packets per second.
Note: Some customers will require a higher threshold or may need unicast storm-control disabled on certain interfaces to support extremely high bandwidth services.