D-Link DCS-6112 User Manual page 52

Configuration
Quality of Service refers to a resource reservation control mechanism, which guarantees a certain quality to different services on the network.
Quality of service guarantees are important if the network capacity is insufficient, especially for real-time streaming multimedia applications.
Quality can be defined as, for instance, a maintained level of bit rate, low latency, no packet dropping, etc.
D-Link DCS-6112 /6113 User Manual 52