QoS Operation

When using the QoS feature, all traffic of the same class receives the same treatment, which consists of a single QoS action of determining the egress queue on the egress port, based on the indicated QoS value in the incoming frame. This is the VLAN Priority Tag (VPT) 802.1p value in Layer 2 and the Differentiated Service Code Point (DSCP) value for IPv4 or Traffic Class (TC) value for IPv6 in Layer 3. When operating in Basic Mode, the switch trusts this external assigned QoS value. The external assigned QoS value of a packet determines its traffic class and QoS.

The type of header field to be trusted is entered in the Global Settings page. For every value of that field, an egress queue is assigned, indicating to which location the frame is sent, in the CoS/802.1p to Queue page or the DSCP to Queue page (depending on whether the trust mode is CoS/802.1p or DSCP, respectively).