Thursday, March 12, 2009

Storm Control

The Storm Control feature protects a LAN from being affected by
unicast, broadcast, or multicast storms that might develop.
The switch implements storm control by counting the number of 
packets of  a specified type received within the one-second 
time interval and compares the measurement with a predefined 
suppression-level threshold. Storm Control can typically enable
the administrator to control traffic by a percentage of total bandwidth 
or the traffic rate at which packets are received. It is important to 
note that when the rate of multicast traffic exceeds a set threshold, 
all incoming traffic (broadcast, multicast, and unicast) is dropped 
until the level drops below the specified threshold level.
Only spanning-tree packets are forwarded in this situation. When 
broadcast and unicast thresholds are exceeded, traffic is blocked for
only the type of traffic that exceeded the threshold.

Storm Control is configured at the interface level with the following

storm-control {broadcast | multicast | unicast} level {level
[level-low] | pps pps [pps-low]}

Best Regards,
Deepak Arora

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