The SonicWall NSA 2400MX appliance can be configured to trust Class of Service (CoS) (IEEE 802.1p) and/or trust Differentiated Services Code Point (DSCP) per port and treat the frames appropriately.
The Switching > Layer 2 QoS page allows you to configure QoS (Qualify of Service) settings per interface.
Four queues with different priority levels (low, normal, high, highest) are supported, as shown in Layer 2 QoS Priority Levels. These are mapped to the eight levels defined in IEEE 802.1p and cannot be changed.
The DSCP mapping can be configured. Frames received on ports configured to trust CoS or DSCP are queued appropriately according to the mapping table. An option is provided to select the field to use when both the 802.1p tag field and the DSCP field are present in incoming frames.
For QoS settings, ports can be assigned a default priority. The default priority is used when Trust CoS or Trust DSCP is enabled, but the information is absent. When Fixed Priority is enabled, the 802.1p tag field and DSCP field are ignored and the default priority is used.