Cisco Nexus 5000 Series Switch CLI Software Configuration Guide, NX-OS 4.0(1a)N1 (OL-16597-01, January 2009)

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15-2
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
OL-16597-01
Chapter 15 Configuring Traffic Storm Control
Guidelines and Limitations
Figure 15-1 Broadcast Suppression
The traffic storm control threshold numbers and the time interval allow the traffic storm control
algorithm to work with different levels of packet granularity. For example, a higher threshold allows
more packets to pass through.
Traffic storm control on the Cisco Nexus 5000 Series switch is implemented in the hardware. The traffic
storm control circuitry monitors packets that pass from a Layer 2 interface to the switching bus. Using
the Individual/Group bit in the packet destination address, the circuitry determines if the packet is
unicast or broadcast, tracks the current count of packets within the 10-microsecond interval, and filters
out subsequent packets when a threshold is reached.
Traffic storm control uses a bandwidth-based method to measure traffic. You set the percentage of total
available bandwidth that the controlled traffic can use. Because packets do not arrive at uniform
intervals, the 10-microsecond interval can affect the operation of traffic storm control.
The following are examples of how traffic storm control operation is affected:
• If you enable broadcast traffic storm control, and broadcast traffic exceeds the level within the
10-microsecond interval, traffic storm control drops all broadcast traffic until the end of the interval.
• If you enable multicast traffic storm control, and the multicast traffic exceeds the level within the
10-microsecond interval, traffic storm control drops all multicast traffic until the end of the interval.
• If you enable broadcast and multicast traffic storm control, and broadcast traffic exceeds the level
within the 10-microsecond interval, traffic storm control drops all broadcast traffic until the end of
the interval.
• If you enable broadcast and multicast traffic storm control, and multicast traffic exceeds the level
within the 10-microsecond interval, traffic storm control drops all multicast traffic until the end of
the interval.
By default, Cisco NX-OS takes no corrective action when the traffic exceeds the configured level.
Guidelines and Limitations
When configuring the traffic storm control level, follow these guidelines and limitations:
• You can configure traffic storm control on a port-channel interface.
• Specify the level as a percentage of the total interface bandwidth:
– The level can be from 0 to 100.
– The optional fraction of a level can be from 0 to 99.
Total
number of
broadcast
packets
or bytes
0T1
Threshold
T2 T4 T5
S5706
T3 Time