H3C Technologies H3C WX5500E Series Access Controllers - Manual (Page 83)

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Configuring storm constrain
The storm constrain function limits traffic of a port within a predefined upper threshold to suppress packet
storms in an Ethernet. With this function enabled on a port, the system detects the amount of broadcast
traffic, multicast traffic, and unknown unicast traffic reaching the port periodically. When a type of traffic
exceeds the threshold for it, the function, as configured, blocks or shuts down the port. Also, it has an
optional setting of sending trap messages and logs.
Alternatively, you can configure the storm suppression function to control a specific type of traffic. For
more information about the storm suppression function, see " Managing ports ." As the storm suppression
function and the storm constrain function are mutually exclusive, do not enable them at the same time on
an Ethernet port. For example, with unknown unicast storm suppression enabled on a port, do not enable
storm constrain for unknown unicast traffic on the port.
With storm constrain enabled on a port, you can specify the system to act as follows when a certain type
of traffic (broadcast, multicast, or unknown unicast) exceeds the upper threshold:
• Block—Blocks the port. The port is blocked and stops forwarding the traffic of this type until the type
of traffic drops down below the lower threshold. A port blocked by the storm constrain function can
still forward other types of traffic and collect statistics for the blocked traffic.
• Shutdown—Shuts down the port. The port is shut down and stops forwarding all types of traffic. It
cannot automatically restore even when the type of traffic drops down below the lower threshold. To
bring up the port, select Device > Port Management to configure the port (see " Managing ports "),
or cancel the storm constrain setting on the port.
Setting the traffic statistics generating interval
When you set the traffic statistics generating interval, follow these guidelines:
• The traffic statistics generating interval set here is the interval used by the storm constrain function
for measuring traffic against the traffic thresholds. It is different from the interval set in the flow
interval module, which is used for measuring the average traffic sending and receiving rates over a
specific interval.
• For network stability sake, set the traffic statistics generating interval for the storm constrain function
to the default or a greater value.
To set the traffic statistics generating interval:
1. From the navigation tree, select Device > Storm Constrain.
2. In the Interval for generating traffic statistics field, enter the traffic statistics generating interval for
storm constrain.
3. Click Apply.