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Configuring Switching
28
SonicOS 5.7: Advanced Switching Feature Guide and Screencast Tutorial
In SonicOS, four queues with different priority levels (low, normal, high, highest) are supported. These are
mapped to the eight levels defined in IEEE 802.1p (CoS) and cannot be changed. Table 4 shows the
mapping between the CoS priority levels and the four supported queue priority levels.
Table 4 802.1p Priority Levels Mapped to Four Queues
On the Switching > Layer 2 QoS page, you can configure the mapping between each value in the DSCP
range of 0-63 and the four queues (Low, Normal, High, Highest) supported for Layer 2 QoS, or reset the
entire map to the default settings (Normal queue for all DSCP values). Also, on the Firewall > QoS Mapping
page, you can configure the mapping between the DSCP range and the 8 levels defined by CoS.
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.
See the following procedures:
• “Configuring the Scheduling Mechanism” on page 28
• “Configuring DSCP Mapping” on page 29
• “Showing the CoS Remap Table” on page 29
• “Configuring QoS Settings” on page 30
Configuring the Scheduling Mechanism
To configure Weighted Round-Robin or Strict Priority Queue as the output scheduling mechanism, perform
the following steps:
Step 1 On the Switching > Layer 2 QoS page, select one of the following from the Output Scheduling
Mechanism drop-down list:
• Weighted Round-Robin – When Weighted Round-Robin is selected, the weighting factors are 8:4:2:1.
CoS Priority Traffic Type Queue Priority
0 Best Effort Normal
1BackgroundLow
2SpareLow
3 Excellent Effort (Business
critical)
Normal
4 Controlled Load (Streaming
multimedia)
High
5 Video (Interactive Media)
[Less than 100ms latency
and jitter]
High
6 Voice [Less than 10ms
latency and jitter]
Highest
7 Network Control [Lowest
latency and jitter]
Highest