Information About Traffic Storm Control
A traffic storm occurs when multicast, broadcast, or unknown-unicast packets flood a port, creating excessive traffic and degrading network performance. Even if the packet rate is not high, the number of clones could be large enough to impact the CPU performance or the switches, servers, and other VEMs on the network. Due to this high CPU usage, the VEM is unable to process the control traffic and traffic disconnects from the VSM. You can use the traffic storm control feature to prevent disruptions from a broadcast, multicast, or unknown-unicast traffic storm on these ports.
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If you enable broadcast traffic storm control, and broadcast traffic exceeds the level within the 1-second interval, traffic storm control drops all broadcast traffic in the next interval. If the broadcast rate is still above the threshold at the start of the next time interval, traffic storm control continues to drop the broadcast traffic.
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If you enable broadcast and multicast traffic storm control, and broadcast traffic exceeds the level within the 1-second interval, traffic storm control drops all broadcast in the next interval. If the broadcast and multicast rate are still above the threshold at the start of the next time interval, traffic storm control continues to drop the broadcast and multicast traffic.
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If you enable broadcast and multicast traffic storm control, and multicast traffic exceeds the level within the 1-second interval, traffic storm control drops all multicast traffic in the next interval. If the multicast rate is still above the threshold at the start of the next time interval, traffic storm control continues to drop multicast traffic.
Traffic storm control is configurable on every port, either through a port profile or directly on the interface (interface override). On physical interfaces and port channels, you can set the threshold as a percentage of the total available bandwidth, the number of bits per second, or the number of packets per second that the controlled traffic can use. On virtual interfaces, you can set the threshold as the number of bits per second or the number of packets per second that the controlled traffic can use. Because packets do not arrive at uniform intervals, the 1-second interval can affect the behavior of traffic storm control.