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Software Configuration Guide—Release 12.2(25)SG
OL-7659-03
Chapter 27 Configuring Quality of Service
Configuring QoS
This example shows how to configure transmit queue 3 to high priority.
Switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# interface gigabitethernet 1/1
Switch(config-if-tx-queue)# tx-queue 3
Switch(config-if-tx-queue)# priority high
Switch(config-if)# end
Switch#
Configuring DSCP Maps
The following sections describes how to configure the DSCP maps. It contains this configuration
information:
• Configuring the CoS-to-DSCP Map, page 27-51
• Configuring the Policed-DSCP Map, page 27-52
• Configuring the DSCP-to-CoS Map, page 27-53
All the maps are globally defined and are applied to all ports.
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 27-4 shows the default CoS-to-DSCP map.
If these values are not appropriate for your network, you need to modify them.
To modify the CoS-to-DSCP map, perform this task:
To return to the default map, use the no qos cos to dscp global configuration command.
Table 27-4 Default CoS-to-DSCP Map
CoS value 012 345 6 7
DSCP value 0 8 16 24 32 40 48 56
Command Purpose
Step 1
Switch# configure terminal
Enters global configuration mode.
Step 2
Switch(config)# qos map cos
cos1 ... cos8
to dscp
dscp
Modifies the CoS-to-DSCP map.
For cos1...cos8, you can enter up to 8 CoS; valid values range
from 0 to 7. Separate each CoS value with a space.
The dscp range is 0 to 63.
Step 3
Switch(config)# end
Returns to privileged EXEC mode.
Step 4
Switch# show qos maps cos-dscp
Verifies your entries.
Step 5
Switch# copy running-config startup-config
(Optional) Saves your entries in the configuration file.
