D-Link Wired DSS-16+ User Manual page 7

Section 1 - Product Overview
IEEE802.1P and QoS
The DSS-16+ switch supports 802.1p priority queuing Quality of Service.The implementation of QoS (Quality of Service)
and benefits of using 802.1p priority queuing are described here.
Advantages of QoS
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 bandwidth can be saved. The switch has separate hardware
queues on every physical port to which packets from various applications are mapped to and assigned a priority.
Mapping QoS on the Switch
In order to implement QoS, the switch will examine the header of a packet to see if it has the proper identifying tag
tagged. Then the switch forwards these tagged packets to designated queues on the switch where they will be emptied,
based on priority.
"The DUT supports strict mode for 802.1p QoS. An untagged packet will follow priority 0 to work (i.e. class 0)."
Understanding QoS
The switch has two priority queues labeled 1 (higher queue), and 0 (lower queue). The eight priority tags, specified in
IEEE 802.1p are mapped to the Switch's priority tags as follows:
Priority 0 is assigned to the Switch's Q0 queue.
Priority 1 is assigned to the Switch's Q0 queue.
Priority 2 is assigned to the Switch's Q0 queue.
Priority 3 is assigned to the Switch's Q0 queue.
Priority 4 is assigned to the Switch's Q1 queue.
Priority 5 is assigned to the Switch's Q1 queue.
Priority 6 is assigned to the Switch's Q1 queue.
Priority 7 is assigned to the Switch's Q1 queue.
The switch uses strict priority for Scheduling. In strict priority-based scheduling, any packets residing in the higher
priority queues are transmitted first.
D-Link DSS-16+ User Manual 7