Consolidated Platform Configuration Guide, Cisco Ios Release 15.2(4)E (Catalyst 2960-X Switches - Cisco Catalyst 2960 series Configuration Manual

DETAILED STEPS
Command or Action
Step 1
configure terminal
Example:
Switch# configure terminal
Step 2 interface interface-id
Example:
Switch(config)# interface
gigabitethernet 1/0/2
Step 3 mls qos trust [cos | dscp | ip-precedence]
Example:
Switch(config-if)# mls qos trust
cos
Step 4 end
Example:
Switch(config-if)# end
Purpose
Enters global configuration mode.
Specifies the port to be trusted, and enters interface configuration mode.
Valid interfaces are physical ports.
Configures 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.
To return a port to its untrusted state, use the no mls qos trust interface
configuration command.
Returns to privileged EXEC mode.

Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)

How to Configure QoS
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