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Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 25 Configuring QoS
Configuring QoS
Configuring the DSCP-to-CoS Map
You use the DSCP-to-CoS map to map DSCP values in incoming packets to a CoS value, which is used
to select one of the four egress queues.
The switch supports these DSCP values: 0, 8, 10, 16, 18, 24, 26, 32, 34, 40, 46, 48, and 56.
Table 25-4 shows the default DSCP-to-CoS 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 DSCP-to-CoS map:
To return to the default map, use the no mls qos map dscp-cos global configuration command.
This example shows how the DSCP values 26 and 48 are mapped to CoS value 7. For the remaining
DSCP values, the DSCP-to-CoS mapping is the default.
Switch(config)# mls qos map dscp-cos 26 48 to 7
Switch(config)# exit
Switch# show mls qos maps dscp-cos
Dscp-cos map:
dscp: 0 8 10 16 18 24 26 32 34 40 46 48 56
-----------------------------------------------
cos: 0 1 1 2 2 3 7 4 4 5 5 7 7
Table 25-4 Default DSCP-to-CoS Map
DSCP values 0 8, 10 16, 18 24, 26 32, 34 40, 46 48 56
CoS values01234567
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
mls qos map dscp-cos dscp-list to cos Modify the DSCP-to-CoS map.
For dscp-list, enter up to 13 DSCP values separated by spaces. Then enter
the to keyword.
For cos, enter the CoS value to which the DSCP values correspond.
The supported DSCP values are 0, 8, 10, 16, 18, 24, 26, 32, 34, 40, 46, 48,
and 56. The CoS range is 0 to 7.
Step 3
end Return to privileged EXEC mode.
Step 4
show mls qos maps dscp-cos Verify your entries.
Step 5
copy running-config startup-config (Optional) Save your entries in the configuration file.