xStack
12
BROADCAST STORM CONTROL COMMANDS
On a computer network, packets such as Multicast packets and Broadcast packets continually flood the network as normal procedure. At times, this traffic may increase do to a malicious endstation on the network or a malfunctioning device, such as a faulty network card. Thus, switch throughput problems will arise and consequently affect the overall performance of the switch network. To help rectify this packet storm, the Switch implements two methods to monitor and control the situation.
1.Hardware: The packet storm is monitored using the Switch’s hardware to determine if too many packets are flooding the network, based on the threshold level provided by the user. Once a packet storm has been detected, the Switch will drop packets coming into the Switch until the storm has subsided. This method can be utilized by selecting the drop option of the Action field in the config traffic control command below.
2.Software: The device’s software will scan and monitor packets coming into the Switch by monitoring the Switch’s chip counter. This method is only viable for Broadcast and Multicast storms because the chip only has counters for these two types of packets. Once a storm has been detected (that is, once the packet threshold set below has been exceeded), the Switch will shutdown the port to all incoming traffic with the exception of STP BPDU packets for a time period, specified using the countdown field. If this field times out and the packet storm continues, the port will be placed in a Shutdown Forever mode which will produce a warning message to be sent to the Trap Receiver. Once in Shutdown Forever mode, the only method of recovering this port is to manually recoup it using the config traffic control_recover setting seen in the command list below. To utilize the Software method of Storm Control, choose the shutdown option of the action field in the config traffic control command below.
The broadcast storm control commands in the Command Line Interface (CLI) are listed (along with the appropriate parameters) in the following table.
Command | Parameters |
config traffic control | [<portlist> all] {broadcast [enabled disabled] multicast [enabled |
| disabled] dlf [enabled disabled] action [drop shutdown] |
| threshold <value |
| time_interval <value |
|
|
config traffic | [<portlist> all] |
control_recover |
|
config traffic trap | [none storm_occurred storm_cleared both] |
|
|
show traffic control | {<portlist>} |
|
|
Each command is listed, in detail, in the following sections.
config traffic control
Purpose | Used to configure broadcast/multicast/dlf packet storm control. |
| The software mechanism is provided to monitor the traffic rate in |
| addition to the hardware storm control mechanism previously |
| provided. |
Syntax | config traffic control [<portlist> all] {broadcast [enabled |
| disabled] multicast [enabled disabled] dlf [enabled |
| disabled] action [drop shutdown] threshold <value 0- |
| 2047> countdown [<value 0> <value |
| <value |
Description | This command is used to configure broadcast/multicast/dlf storm |
| control. By adding the new software traffic control mechanism, the |
| user can now use both a hardware and software mechanism, the |
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