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DES-3550 Fast Ethernet Layer 2 Switch
The following parameters can be set or are displayed:
Parameter Description
From/To
A consecutive group of ports may be configured starting with the selected port.
Type
This drop-down menu allows you to select between RX (receive,) TX (transmit,) and
Both. This setting will determine whether the bandwidth ceiling is applied to receiving,
transmitting, or both receiving and transmitting packets.
no_limit
This drop-down menu allows you to specify that the selected port will have no
bandwidth limit. Enabled disables the limit.
Rate
This field allows you to enter the data rate, in kb/s, that will be the limit for the selected
port.
Click Apply to set the bandwidth control for the selected ports. Results of configured Bandwidth Settings will be
displayed in the Port Bandwidth Table.
Scheduling
QoS can be customized by changing the output scheduling used for the hardware queues in the Switch. As with any
changes to QoS implementation, careful consideration should be given to how network traffic in lower priority queues is
affected. Changes in scheduling may result in unacceptable levels of packet loss or significant transmission delay. If you
choose to customize this setting, it is important to monitor network performance, especially during peak demand, as
bottlenecks can quickly develop if the QoS settings are not suitable. In the Configuration folder open the QoS folder and
click QoS Output Scheduling, to view the screen shown below.
Figure 6- 44. QoS Output Scheduling Configuration window
You may assign the following values to the QoS classes to set the scheduling.
Parameter Description
Max. Packets(0-255)
Specifies the maximum number of packets the above specified hardware priority
queue will be allowed to transmit before allowing the next lowest priority queue to
transmit its packets. A value between 0 and 255 can be specified.
Max. Latency(0-255)
Specifies the maximum amount of time the above specified hardware priority
queue will be allowed to transmit packets before allowing the next lowest
hardware priority queue to begin transmitting its packets. A value between 0 and
255 can be specified - with this value multiplied by 16 ms to arrive at the total
allowed time for the queue to transmit packets. For example, a value of 3
specifies 3 X 16 = 48 ms. The queue will continue transmitting the last packet until
it is finished when the max latency timer expires.
Click Apply to implement changes made.
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