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Software Configuration Guide—Release 12.2(25)SG
OL-7659-03
Chapter 27 Configuring Quality of Service
Configuring QoS
Note In the above policed-DSCP map, the marked-down DSCP values are shown in the body of the matrix.
The d1 column specifies the most-significant digit of the original DSCP; the d2 row specifies the
least-significant digit of the original DSCP. The intersection of the d1 and d2 values provides the
marked-down value. For example, an original DSCP value of 53 corresponds to a marked-down DSCP
value of 0.
Configuring the DSCP-to-CoS Map
You use the DSCP-to-CoS map to generate a CoS value.
Table 27-5 shows the default DSCP-to-CoS map.
If the values above are not appropriate for your network, you need to modify them.
To modify the DSCP-to-CoS map, perform this task:
To return to the default map, use the no qos dscp to cos global configuration command.
This example shows how to map DSCP values 0, 8, 16, 24, 32, 40, 48, and 50 to CoS value 0 and to
display the map:
Switch# configure terminal
Switch(config)# qos map dscp 0 8 16 24 32 40 48 50 to cos 0
Switch(config)# end
Switch# show qos maps dscp cos
Table 27-5 Default DSCP-to-CoS Map
DSCP value 0–7 8–15 16–23 24–31 32–39 40–47 48–55 56–63
CoS value 012345 6 7
Command Purpose
Step 1
Switch# configure terminal
Enters global configuration mode.
Step 2
Switch(config)# qos map dscp
dscp-list
to cos
cos
Modifies the DSCP-to-CoS map.
• For dscp-list, enter up to 8 DSCP values separated by spaces.
Then enter the to keyword.
• For cos, enter only one CoS value to which the DSCP values
correspond.
The DSCP range is 0 to 63; the CoS range is 0 to 7.
Step 3
Switch(config)# end
Returns to privileged EXEC mode.
Step 4
Switch# show qos maps dscp to cos
Verifies your entries.
Step 5
Switch# copy running-config
startup-config
(Optional) Saves your entries in the configuration file.