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The IEEE 802.1p standard uses eight levels of priority (0-7). Priority 7 is assigned to highest priority
network traffic, such as OSPF or RIP routing table updates, priorities 5-6 are assigned to delay-sensitive
applications such as voice and video, and lower priorities are assigned to standard applications. A value
of 0 (zero) indicates a best effort traffic prioritization, and this is the default when traffic priority has not
been configured on your network. The switch can filter packets based on the 802.1p values, and it can
assign or overwrite the 802.1p value in the packet.
Figure 13 Layer 2 802.1q/802.1p VLAN tagged packet
Ingress packets receive a priority value, as follows:
• Tagged packets—the switch reads the 802.1p priority in the VLAN tag.
• Untagged packets—the switch tags the packet and assigns an 802.1p priority, based on the port’s
default priority (/cfg/port x/8021ppri).
Egress packets are placed in a COS queue based on the priority value, and scheduled for transmission
based on the scheduling weight of the COS queue.
Use the /cfg/qos/8021p/cur command to display the mapping between 802.1p values, Class of
Service queues (COSq), and COSq scheduling weights.
>> 802.1p# cur
Current priority to COS queue configuration:
Number of COSq: 2
Priority COSq Weight
-------- ---- ------
0 0 1
1 0 1
2 0 1
3 0 1
4 1 2
5 1 2
6 1 2
7 1 2