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Chapter 31
Configuring QoS
To return a port to its untrusted state, use the no mls qos trust interface configuration command.
For information on how to change the default CoS value, see the
Interface" section on page
Configuring the CoS Value for an Interface
QoS assigns the CoS value specified with the mls qos cos interface configuration command to untagged
frames received on trusted and untrusted ports.
Beginning in privileged EXEC mode, follow these steps to define the default CoS value of a port or to
assign the default CoS to all incoming packets on the port:
Command
Step 1
configure terminal
Step 2
interface interface-id
Step 3
mls qos cos {default-cos | override}
Step 4
end
Step 5
show mls qos interface
Step 6
copy running-config startup-config
To return to the default setting, use the no mls qos cos {default-cos | override} interface configuration
command.
Enabling DSCP Transparency Mode
The switch supports the Differentiated Services Code Point (DSCP) transparency feature. It affects only
the DSCP field of a packet at egress. By default, DSCP transparency is disabled. The switch modifies
the DSCP field in an incoming packet, and the DSCP field in the outgoing packet is based on the QoS
configuration, including the port trust setting, policing and marking, and the DSCP-to-DSCP mutation
map.
OL-23389-01
31-11.
Purpose
Enter global configuration mode.
Specify the port to be configured, and enter interface configuration mode.
Valid interfaces include physical ports.
Configure the default CoS value for the port.
For default-cos, specify a default CoS value to be assigned to a port. If
•
the packet is untagged, the default CoS value becomes the packet CoS
value. The CoS range is 0 to 7. The default is 0.
Use the override keyword to override the previously configured trust
•
state of the incoming packet and to apply the default port CoS value to
the port on all incoming packets. By default, CoS override is disabled.
Use the override keyword when all incoming packets on specified ports
deserve higher or lower priority than packets entering from other ports.
Even if a port was previously set to trust CoS or IP precedence, this
command overrides the previously configured trust state, and all the
incoming CoS values are assigned the default CoS value configured
with this command. If an incoming packet is tagged, the CoS value of
the packet is modified with the default CoS of the port at the ingress
port.
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
Catalyst 2928 Switch Software Configuration Guide
Configuring Standard QoS
"Configuring the CoS Value for an
31-11
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Troubleshooting
