Configuring Layer 2 QoS

Layer 2 Quality of Service (QoS) allows for traffic prioritization and bandwidth management to minimize network delay using Cost of Service (CoS) classification, and DSCP marking.

 

A Dell SonicWALL 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 the administrator to configure QoS settings per interface. The X1 interface on the NSA 2400MX cannot be configured for switching.

Four queues with different priority levels (low, normal, high, highest) are supported. These are mapped to the eight levels defined in IEEE 802.1p and cannot be changed:

 

Table 9. Supported queues with different priority levels

User Priority	Traffic Type	Queue Priority
0	Best Effort	Normal
1	Background	Low
2	Spare	Low
3	Excellent Effort	Normal
4	Controlled Load	High
5	Video	High
6	Voice	Highest
7	Network Control	Highest

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 ingressing 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.

Refer to the following configuration procedures:

•	Configuring the Scheduling Mechanism

•	Configuring DSCP Mapping

•	Configuring QoS Settings