Administrator's Guide v4.1.1 Manual

Understanding default user-priority mappings for untrusted interfaces
When Layer 2 QoS trust is set to untrusted , then the default is to map all Layer 2 switched traffic to the
port default user priority value of 0 (best effort), unless the user priority is configured to a different value.
The following table presents the Layer 2 QoS untrusted user-priority generation table.
Default priority value of untrusted interfaces TABLE 82
Incoming CoS User Priority
0 port <user priority> (default 0)
1 port <user priority> (default 0)
2 port <user priority> (default 0)
3 port <user priority> (default 0)
4 port <user priority> (default 0)
5 port <user priority> (default 0)
6 port <user priority> (default 0)
7 port <user priority> (default 0)
NOTE
Nontagged Ethernet frames are interpreted as having an incoming CoS value of 0 (zero).
You can override the default user-priority mapping by applying explicit user-priority mappings.
When neighboring devices are trusted and able to properly set QoS, then Layer 2 QoS trust can be set
to CoS and the IEEE 802.1Q default-priority mapping is applied.
The following table presents the Layer 2 CoS user-priority generation table conforming to 802.1Q
default mapping. You can override this default user-priority table per port if you want to change (mutate)
the CoS value.
IEEE 802.1Q default priority mapping TABLE 83
Incoming CoS User Priority
0 0
1 1
2 2
3 3
4 4
5 5
Understanding default user-priority mappings for untrusted interfaces
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