Dell PC2716, PC2748, PC2708, PC2724 manual CoS Services

Packets arriving untagged are assigned a default VPT value, which is set on a per port basis. The assigned VPT is used to map the packet to the egress queue.

DSCP values can be mapped to priority queues. DSCP mapping is enabled on a per-system basis. The following table contains the default DSCP mapping to egress queue values:

Table 7-2. DSCP Mapping to Egress Queue Default Values

DSCP Value	Forwarding Queue Values
0-15	q1	(Lowest Priority)
16-31	q2
32-47	q3
48-63	q4	(Highest Priority)

CoS Services

After packets are assigned to a specific egress queue, CoS services can be assigned to the queue(s). Egress queues are configured with a scheduling scheme by one of the following methods:

•Strict Priority — Strict Priority (SP) allows the prioritization of mission-critical and time- sensitive traffic over less time-sensitive applications. Thus, ensuring that time-sensitive applications are always forwarded before traffic with lower priority. For example, under Strict Priority, voice over IP traffic is forwarded before FTP or e-mail (SMTP) traffic.

•Weighted Round Robin — Ensures that a single application does not dominate the Ethernet switch forwarding capacity. Weighted Round Robin (WRR) forwards entire queues in a Round Robin order. All queues can participate in WRR.

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