Allied Telesis AT-GS950/48, User Manual

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AT-GS950/48 Web Interface User Guide
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instance, as long as there are packets in the Highest queue, it does not
handle any packets in the High queue. The value of this type of scheduling
is that high-priority packets are always handled before low-priority packets
which is required for voice or video data.
The problem with this method is that some low-priority packets might
never be transmitted from the switch because the algorithm might never
have time to process the packets waiting in the lower-priority queues.
Weighted Round Robin Priority Scheduling
The weighted round robin (WRR) scheduling method functions as its name
implies. The port transmits a set number of packets from each queue, in a
round robin fashion, so that each has a chance to transmit traffic.
Normally, the higher the queue’s priority, the more packets are transmitted
in as the algorithm cycles through the queues in turn. This method
guarantees that every queue receives some attention from the port for
transmitting packets.
Table 4 shows the WRR settings for the number of packets transmitted
from each queue. These values are permanent, and you cannot change
these values.
Table 4. Example of Weighted Round Robin Priority
Port Egress Queue
Maximum Number of
Packets
Highest 8
High 4
Medium 2
Low 1