Cisco Catalyst 3750 - Page 525

26-45
Catalyst 3750 Metro Switch Software Configuration Guide
78-15870-01
Chapter 26 Configuring QoS
Configuring Standard 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 “Configuring the CoS Value for an
Interface” section on page 26-45. For information on how to configure the CoS-to-DSCP map, see the
“Configuring the CoS-to-DSCP Map” section on page 26-59.
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 inbound packets on the port:
To return to the default setting, use the no mls qos cos {default-cos | override} interface configuration
command.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface interface-id Specify the port to be configured, and enter interface configuration mode.
Valid interfaces include physical ports.
Step 3
mls qos cos {default-cos | override} Configure the default CoS value for the port.
For 802.1Q tunnels, the switch processes inbound traffic on a standard port
according to the trusted setting applied to this port. The switch configures
the inner and outer tags for packets sent over the ES trunk 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.
For 802.1Q tunnels, the switch copies the inner CoS value to the outer
CoS value and sends the packet out an ES port.
• Use the override keyword to override the previously configured trust
state of the inbound packet and to apply the default port CoS value to
the port on all inbound packets. By default, CoS override is disabled.
Use the override keyword when all inbound packets on specified ports
deserve higher or lower priority than packets entering from other ports.
Even if a port was previously set to trust DSCP, CoS, or IP precedence,
this command overrides the previously configured trust state, and all
the inbound CoS values are assigned the default CoS value configured
with this command. If an inbound packet is tagged, the CoS value of the
packet is modified with the default CoS of the port at the ingress port.
For 802.1Q tunnels, the switch copies the port CoS value to the outer
CoS value, does not modify the inner CoS value, and sends the packet
out an ES port.
Step 4
end Return to privileged EXEC mode.
Step 5
show mls qos interface Verify your entries.
Step 6
copy running-config startup-config (Optional) Save your entries in the configuration file.