D-Link xStack Reference Manual page 133

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xStack DGS-3200 Series Layer 2 Managed Gigabit Ethernet Switch Web UI Reference Guide
QoS
Bandwidth Control
Queue Bandwidth Control Settings
Traffic Control
802.1p Default Priority
802.1p User Priority
QoS Scheduling Mechanism
QoS is an implementation of the IEEE 802.1p standard that allows network administrators a method of reserving bandwidth for
important functions that require a large bandwidth or have a high priority, such as VoIP (voice-over Internet Protocol), web
browsing applications, file server applications or video conferencing. Not only can a larger bandwidth be created, but other less
critical traffic can be limited, so excessive bandwidth can be saved. The Switch has separate hardware queues on every physical
port to which packets from various applications can be mapped to, and, in turn prioritized. View the following map to see how the
Switch implements basic 802.1P priority queuing.
Figure 5 - 1. An Example of the Default QoS Mapping on the Switch
The picture above shows the default priority setting for the Switch. Class-7 has the highest priority of the seven priority classes of
service 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. Then the user may forward these tagged packets to designated classes of service on the
Switch where they will be emptied, based on priority.
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