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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
Chapter 39 Configuring QoS
Configuring Standard QoS
Configuring the CoS-to-DSCP Map
You use the CoS-to-DSCP map to map CoS values in incoming packets to a DSCP value that QoS uses
internally to represent the priority of the traffic.
Table 39-12 shows the default CoS-to-DSCP map.
If these values are not appropriate for your network, you need to modify them.
Beginning in privileged EXEC mode, follow these steps to modify the CoS-to-DSCP map. This
procedure is optional.
To return to the default map, use the no mls qos cos-dscp global configuration command.
This example shows how to modify and display the CoS-to-DSCP map:
Switch(config)# mls qos map cos-dscp 10 15 20 25 30 35 40 45
Switch(config)# end
Switch# show mls qos maps cos-dscp
Cos-dscp map:
cos: 0 1 2 3 4 5 6 7
--------------------------------
dscp: 10 15 20 25 30 35 40 45
Tab le 39-12 Default CoS-to-DSCP Map
CoS Value DSCP Value
0 0
1 8
216
324
432
540
648
756
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 mls qos map cos-dscp dscp1...dscp8 Modify the CoS-to-DSCP map.
For dscp1...dscp8, enter eight DSCP values that correspond to CoS values
0 to 7. Separate each DSCP value with a space.
The DSCP range is 0 to 63.
Step 3 end Return to privileged EXEC mode.
Step 4 show mls qos maps cos-dscp Verify your entries.
Step 5 copy running-config startup-config (Optional) Save your entries in the configuration file.