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Storm Control
Storm Control
The Storm Control feature protects against conditions where incoming packets flood the LAN, causing
network performance degradation. The software includes Storm Control protection for unicast traffic
with an unknown destination, and for broadcast and multicast traffic.
Storm control provides the possibility of disabling an interface on which a storm is detected to prevent
unnecessary congestion in the network. When enabled, the storm control threshold is automatically set
to 5% of port speed. If the incoming rate of unicast (with unknown destination), multicast, or broadcast
packets exceeds this value, the port moves to the diagnostically disabled state and remains in that
state until it is re-enabled by the Auto Recovery feature or re-enabled manually by enabling it in the
Port Configuration Status page (see
). If the interface continues to encounter
excessive traffic, it may be placed back into the diagnostically disabled state, and the interface will be
disabled (link down). Storm Control functionality is applicable only to the physical interfaces.
Use the Storm Control Configuration page to configure the storm control administrative mode and to
set the Auto Recovery option for Storm Control.
To display the Storm Control Configuration page, click
Security
>
Storm
in the navigation pane.
Figure 129. Storm Control Configuration
NOTE:
The storm control threshold percentage is translated to a packets-per-second value that is used by
the switch hardware to rate-limit the incoming traffic. This translation assumes a nominal 512 byte
packet size to determine the packets-per-second threshold based on the port speed. For example,
the 5% threshold applied to a 1 Gbps port equates to approximately 11748 packets-per-second,
regardless of the actual packet sizes received by the port.
