System Configuration 23
Storm Control
A traffic storm occurs when incoming packets flood the LAN resulting in network performance
degradation. The Storm Control feature protects against this condition.
The switch software provides broadcast, multicast, and unicast storm recovery for individual interfaces.
Unicast Storm Control protects against traffic whose MAC addresses are not known by the system.
For broadcast, multicast, and unicast storm control, if the rate of traffic ingressing on an interface
increases beyond the configured threshold for that type, the traffic is dropped.
To configure storm control, you will enable the feature for all interfaces or for individual interfaces, and
you will set the threshold (storm control level) beyond which the broadcast, multicast, or unicast traffic
will be dropped.
Configuring a storm-control level also enables that form of storm-control. Disabling a storm-control level
(using the “no” version of the command) sets the storm-control level back to default value and disables
that form of storm-control. Using the “no” version of the “storm-control” command (not stating a
“level”) disables that form of storm-control but maintains the configured “level” (to be active next time
that form of storm-control is enabled).
NOTE: The actual rate of ingress traffic required to activate storm-control is based on the size of incoming packets
and the hard-coded average packet size of 512 bytes - used to calculate a packet-per-second (pps) rate - as the
forwarding-plane requires pps versus an absolute rate Kbps. For example, if the configured limit is 10%, this is
converted to ~25000 pps, and this pps limit is set in forwarding plane (hardware). You get the approximate desired
output when 512bytes packets are used.
CLI Example
The following examples show how to configure the storm control feature an Ethernet interface. The
interface number is 1/g17.
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