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Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 37 Configuring Quality of Service
Configuring Auto-QoS on Supervisor Engines II-Plus, II+10GE, IV, V, V-10GE, 4924, 4948, and 4948-10GE
To modify the DSCP-to-CoS map, perform this task:
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
Dscp-cos map:
d1 : d2 0 1 2 3 4 5 6 7 8 9
---------------------------------------
0 : 00 00 00 00 00 00 00 00 00 01
1 : 01 01 01 01 01 01 00 02 02 02
2 : 02 02 02 02 00 03 03 03 03 03
3 : 03 03 00 04 04 04 04 04 04 04
4 : 00 05 05 05 05 05 05 05 00 06
5 : 00 06 06 06 06 06 07 07 07 07
6 : 07 07 07 07
Note In the previous DSCP-to-CoS map, the CoS values are shown in the body of the matrix. The d1 column
specifies the most-significant digit of the DSCP; the d2 row specifies the least-significant digit of the
DSCP. The intersection of the d1 and d2 values provides the CoS value. For example, in the
DSCP-to-CoS map, a DSCP value of 08 corresponds to a CoS value of 0.
Configuring Auto-QoS on Supervisor Engines II-Plus, II+10GE, IV, V, V-10GE, 4924, 4948, and 4948-10GE
You can use the auto-QoS feature to simplify the deployment of existing QoS features. Auto-QoS makes
assumptions about the network design, and as a result, the switch can prioritize different traffic flows
and appropriately use the egress queues instead of using the default QoS behavior. (The default is that
QoS is disabled. The switch then offers best-effort service to each packet, regardless of the packet
content or size, and sends it from a single queue.)
Command Purpose
Step 1 Switch# configure terminal Enters global configuration mode.
Step 2 Switch(config)# [no] qos map dscp
dscp-list to cos cos Modifies the DSCP-to-CoS map.
For dscp-list, enter up to eight DSCP values separated by
spaces. Next, 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.
To return to the default map, use the no qos dscp to cos global
configuration command.
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.