For more information about 802.1p priority and DSCP values, see "Packet precedences."

Local precedence is a locally significant precedence that the device assigns to a packet. A local precedence value corresponds to an output queue. Packets with the highest local precedence are processed preferentially.

The device provides the following priority trust modes on a port:

Trust packet priority—The device assigns to the packet the priority parameters corresponding to the packet's priority from the mapping table.

Trust port priority—The device assigns a priority to a packet by mapping the priority of the receiving port.

You can select one priority trust mode as needed. Figure 462 shows the process of priority mapping on a device.

Figure 462 Priority mapping process

Introduction to priority mapping tables

The device provides the following types of priority mapping tables:

CoS to Queue—802.1p--to-local mapping table.

DSCP to Queue—DSCP-to-local mapping table, which applies to only IP packets.

Table 148 through Table 149 list the default priority mapping tables.

Table 148 Default CoS to Queue mapping table

Input CoS value

Local precedence (Queue)

0

2

 

 

1

0

 

 

2

1

 

 

3

3

 

 

4

4

 

 

5

5

 

 

6

6

 

 

7

7

 

 

 

475