D-Link DGS-3212SR Layer 2 Gigabit Ethernet Switch
Section 11
Quality of Service Configuration
QoS settings allow customization of packet priority in order to facilitate delivery of data traffic that might be
affected by latency problems. The IEEE 802.1p Priority specification uses 8 priority levels to classify data
packets. In 802.1p compliant devices, a tag inserted into the packet header is used to identify the priority level of
data packets.
The Switch implements 802.1p priority using 4 hardware queues instead of 8. Therefore the Switch must have a
means of mapping the 8 levels specified in the IEEE 802.1p standard to the 4 hardware queues used in the
Switch. This is done using the Class of Service menu explained below. Further customization of priority
classification can be done with the Output Scheduling menu, also explained below.
Individual ports may still be assigned priority using the 8 levels as defined by the 802.1p standard.
It is important to note that changes in a network’s QoS scheme should be carefully considered, planned for, and
if possible, tested for efficiency. When set up properly, QoS can allow efficient and timely delivery of data for
video conferencing or IP telephony without causing unacceptable delays of other network traffic. If QoS is not
well set up however, significant delays and excessive packet loss may result for data assigned to lower priority
queues.
Traffic Control (Broadcast/Multicast Storm Control)
Use the Traffic Control Setting menu to enable or disable storm control and adjust the threshold for multicast and
broadcast storms, as well as DLF (Destination Look Up Failure). Traffic control settings are applied to individual
Switch modules.
Figure 10-3. Traffic Control Settings
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