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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter12 Configuring Port-Based Tra ffic Control Configuring Storm Control
Note Before IOS Release 12.1(8)EA1, you set up storm control threshold values by using the switchport
broadcast, switchport multicast, and switchport unicast interface configuration commands. These
commands are now obsolete, replaced by the storm-control interface configuration commands.
Default Storm Control Configuration
By default, unicast, broadcast, and multicast storm control is disabled on the switch: that is, the
suppression level is 100 percent.
Enabling Storm Control
You enable storm control on an interface and enter the percentage of total available bandwidth th at you
want to be used by a particular type of traffic; entering 100 percent allows all traffic. However, because
of hardware limitations and the way in which packets of different sizes are counted, threshold
percentages are approximations. Depending on the sizes of the packets maki ng u p the incoming traffic,
the actual enforced threshold might differ from the configured level by several percentage points.
Note Storm control is supported only on physical interfaces; it is n ot suppor t ed on E the rChann el por t
channels even though the command is available in the CLI.
Beginning in privileged EXEC mode, follow these steps to ena ble a pa rtic ula r ty pe of stor m co ntro l:
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface interface-id Enter interface configuration mode, and enter the type and number
of the physical interface to configure, for example,
gigabitethernet0/1.
Step3 storm-control broadcast level level [.level] Specify the br oadcast traffic suppression level for an interface as a
percentage of total bandwidth. The level can be from 1 t o 100; the
optional fraction of a level can be from 0 to 99. A threshold value
of 100percent means that no limit is placed on broadcast traffic. A
value of 0.0 means that all broadcast traffic on that port is blocked.
Step4 storm-control multicast level level [.level] Specify the multicast traffic suppression level for an interface as a
percentage of total bandwidth. The level can be from 1 t o 100; the
optional fraction of a level can be from 0 to 99. A threshold value
of 100percent means that no limit is placed on broadcast traffic. A
value of 0.0 means that all multicast traffic on that port is blocked.
Step5 storm-control unicast level level [.level] Specify the unicast traffic suppression level for an interface as a
percentage of total bandwidth. The level can be from 1 t o 100; the
optional fraction of a level can be from 0 to 99. A threshold value
of 100percent means that no limit is placed on broadcast traffic. A
value of 0.0 means that all unicast traffic on that port is blocked.
Step6 end Return to privileged EXEC mode.