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DES-3500 Layer 2 Fast Ethernet Switch CLI Reference Manual
97
13
TRAFFIC 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 will monitor and control the situation.
The packet storm is monitored 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 window below.
The Switch will also 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, one method of recovering this port is to manually
recoup it using the Port Configuration window in the Administration folder and selecting the disabled port and returning it to an
Enabled status. Otherwise, the Shutdown Forever mode will be Auto-Recovery after 5 mins.To utilize this method of Storm
Control, choose the Shutdown option of the Action field in the window 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 [enable| disable]| multicast [enable|
disable] | dlf [enable | disable] | action [drop | shutdown] |
threshold <value>| time_interval <secs 5-30 > | countdown
<minutes 0 | 5-30> }
show traffic control {[group_list <storm_grouplist> | port <portlist>]}
config traffic control_trap [none|storm_occurred|storm_cleared|both]
Each command is listed, in detail, in the following sections.
config traffic control
Purpose Used to configure broadcast/multicast/unicast 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 [enable| disable]|
multicast [enable| disable] | dlf [enable | disable] | action [drop |
shutdown] | threshold <value>|time_interval <secs 5-30 > |
countdown <minutes 0 | 5-30>}
Description This command is used to configure broadcast/multicast/unicast storm
control. By adding the new software traffic control mechanism, the user
can now use both a hardware and software mechanism, the latter of
which will now provide shutdown, recovery and trap notification functions
for the Switch.
Parameters
<storm_grouplist> − Used to specify a group list of ports to be configured
for traffic control, as defined below:
Group 1 – Inclusive for ports 1-8.
Group 2 - Inclusive for ports 9-16.
Group 3 - Inclusive for ports 17-24.
Group 4 - Inclusive for ports 9-16 (DES-3550). Inclusive for Gigabit
port 25 (DES-3526).
Group 5 - Inclusive for ports 33-40 (DES-3550). Inclusive for Gigabit
port 26 (DES-3526).