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Storm control, Figure 137 confi – Brocade 6910 Ethernet Access Switch Configuration Guide (Supporting R2.2.0.0) User Manual

Page 864

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Brocade 6910 Ethernet Access Switch Configuration Guide

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38

Storm Control

4. Click Apply.

FIGURE 137

Configuring Rate Limits

Storm Control

Use the Traffic > Storm Control page to configure broadcast, multicast, and unknown unicast storm
control thresholds. Traffic storms may occur when a device on your network is malfunctioning, or if
application programs are not well designed or properly configured. If there is too much traffic on
your network, performance can be severely degraded or everything can come to complete halt.

You can protect your network from traffic storms by setting a threshold for broadcast, multicast or
unknown unicast traffic. Any packets exceeding the specified threshold will then be dropped.

CLI References

“switchport packet-rate”

on page 263

Command Usage

Broadcast Storm Control is enabled by default.

Broadcast control does not effect IP multicast traffic.

When traffic exceeds the threshold specified for broadcast and multicast or unknown unicast
traffic, packets exceeding the threshold are dropped until the rate falls back down beneath the
threshold.

Traffic storms can be controlled at the hardware level using this command, or at the software
level using automatic storm control which triggers various control responses (see

“Automatic

Traffic Control Commands”

on page 309). However, only one of these control types can be

applied to a port. Enabling hardware-level storm control on a port will disable automatic storm
control on that port.

The rate limits set by this function are also used by automatic storm control when the control
response is set to rate limiting by the

auto-traffic-control action

command.

Using both rate limiting and storm control on the same interface may lead to unexpected
results. For example, suppose broadcast storm control is set to 500 pps by the command
“switchport broadcast packet-rate 500" and the rate limit is set to 200 Mbps by the command
“rate-limit input 20" on a port. Since 200 Mbps is 1/5 of line speed (1000 Mbps), the received
rate will actually be 100 pps, or 1/5 of the 500 pps limit set by the storm control command. It
is therefore not advisable to use both of these commands on the same interface.