D-Link DGS-3100 User Manual page 98

DGS-3100 Series Gigabit Stackable Managed Switch User Manual
Figure 4-1. Mapping QoS on the Switch
The picture above shows the default priority setting for the Switch. Class-3 has the highest priority of the four priority
queues on the Switch. In order to implement QoS, the user is required to instruct the Switch to examine the header of a
packet to see if it has the proper identifying tag tagged. Then the user may forward these tagged packets to designated
queues on the Switch where they will be emptied, based on priority.
For example, let us say a user wishes to have a video conference between two remotely set computers. The administrator
can add priority tags to the video packets being sent out, utilizing the Access Profile commands. Then, on the receiving end,
the administrator instructs the Switch to examine packets for this tag, acquires the tagged packets and maps them to a class
queue on the Switch. Then in turn, the administrator will set a priority for this queue so that it will be emptied before any
other packet is forwarded. This process results in the end user receiving all packets sent as quickly as possible, thus
prioritizing the queue and allowing for an uninterrupted stream of packets, which optimizes the use of bandwidth available
for the video conference.
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