Configuring The Cos Value For An Interface - Cisco Catalyst 3750-X Software Configuration Manual

Chapter 39 Configuring QoS
Beginning in privileged EXEC mode, follow these steps to configure the port to trust the classification
of the traffic that it receives:
Command
Step 1
configure terminal
Step 2
interface interface-id
mls qos trust [cos | dscp | ip-precedence]
Step 3
Step 4
end
Step 5
show mls qos interface
Step 6
copy running-config startup-config
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-to-DSCP Map" 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
OL-21521-01
Purpose
Enter global configuration mode.
Specify the port to be trusted, and enter interface configuration
mode. Valid interfaces are physical ports.
Configure the port trust state.
By default, the port is not trusted. If no keyword is specified, the
default is dscp.
The keywords have these meanings:
cos—Classifies an ingress packet by using the packet CoS value.
•
For an untagged packet, the port default CoS value is used. The
default port CoS value is 0.
dscp—Classifies an ingress packet by using the packet DSCP
•
value. For a non-IP packet, the packet CoS value is used if the
packet is tagged; for an untagged packet, the default port CoS is
used. Internally, the switch maps the CoS value to a DSCP value
by using the CoS-to-DSCP map.
ip-precedence—Classifies an ingress packet by using the packet
•
IP-precedence value. For a non-IP packet, the packet CoS value
is used if the packet is tagged; for an untagged packet, the default
port CoS is used. Internally, the switch maps the CoS value to a
DSCP value by using the CoS-to-DSCP map.
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
39-41. For information on how to configure the CoS-to-DSCP map, see the
Purpose
Enter global configuration mode.
Specify the port to be configured, and enter interface configuration mode.
Valid interfaces include physical ports.
Catalyst 3750-X and 3560-X Switch Software Configuration Guide
Configuring Standard QoS
"Configuring the CoS Value for an
39-70.
39-41