xStack
®
DGS-3200 Series Layer 2 Gigabit Ethernet Managed Switch
92
Traffic Control
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.
Packet storms are monitored to determine if too many packets are flooding the network based on threshold levels 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 parameter 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 shut down the port to all
incoming traffic, with the exception of STP BPDU packets, for a time period specified using the Count Down parameter.
If a Time Interval parameter times-out for a port configured for traffic control and a packet storm continues, that port will be
placed in Shutdown Forever mode, which will cause a warning message to be sent to the Trap Receiver. Once in Shutdown
Forever mode, the only method of recovering the port is to manually recoup it using the
Port Settings
window in the
Configuration
folder. Select the disabled port and return its State to
Enabled
status. To utilize this method of Storm Control,
choose the
Shutdown
option of the
Action parameter in the window below.
Use this window to enable or disable storm control and adjust the threshold for multicast and broadcast storms.
To view the following window, click
QoS > Traffic Control
:
Figure 4 - 3. Traffic Control window
To configure Traffic Control, set the parameters described in the table below:
Parameter Description
From Port
Select the beginning port of the range of port(s) to be configured.
To Port
Select the ending port of the range of port(s) to be configured.
Action
Select the method of traffic control from the pull-down menu. The choices are:
Drop
– Utilizes the hardware Traffic Control mechanism, which means the Switch’s hardware will
determine the Packet Storm based on the Threshold value stated and drop packets until the issue is
resolved.
Shutdown
– Utilizes the Switch’s software Traffic Control mechanism to determine the Packet Storm
occurring. Once detected, the port will deny all incoming traffic to the port except STP BPDU packets,
which are essential in keeping the Spanning Tree operational on the Switch. If the Count Down timer
has expired and yet the Packet Storm continues, the port will be placed in Shutdown Forever mode
