1-7
For incoming 802.1q tagged packets, you can configure the switch to trust packet priority with the
priority trust command or to trust port priority with the undo priority trust command. By default, the
4210 series switches trust port priority.
z Trusting port priority
In this mode, the switch replaces the 802.1p priority of the received packet with the port priority,
searches for the local precedence corresponding to the port priority of the receiving port in the
802.1p-to-local precedence mapping table, and assigns the local precedence to the packet.
z Trusting packet priority
After configuring to trust packet priority, you can specify the trusted priority type, which can be 802.1p
priority or DSCP precedence. With trusting packet priority enabled, the switch trusts the 802.1p priority
of received packets.
Table 1-5 describes the two trusted packet priority types.
Table 1-5 Description on the two trusted packet priority types
Trusted priority type Description
802.1p priority
The switch searches for the local precedence corresponding to the
802.1p priority of the packet in the 802.1p-to-local precedence mapping
table and assigns the local precedence to the packet.
DSCP precedence
The switch searches for the local precedence corresponding to the
DSCP value of the packet in the DSCP-to-local precedence mapping
table and assigns the local precedence to the packet.
The 4210 series switches provide 802.1p-to-local-precedence and DSCP-to-local-precedence mapping
tables for priority mapping.
Table 1-6 through Table 1-7 list the default settings of these tables. You can
configure these default priority mapping tables at the CLI. For detailed configuration, refer to
Configuring Priority Trust Mode.
Table 1-6 CoS-precedence-to-local-precedence mapping table
CoS Local precedence
0 1
1 0
2 0
3 1
4 2
5 2
6 3
7 3
Table 1-7 DSCP-precedence-to-local-precedence mapping table
DSCP Local precedence
0 to 15 0
16 to 31 1
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