Trust - Cisco Catalyst 4500 Series Command Reference Manual

trust

trust
To define a trust state for traffic classified through the class policy-map configuration command, use the
trust policy-map class configuration command. To return to the default setting, use the no form of this
command.
Syntax Description
cos
dscp
Defaults
The action is not trusted.
Command Modes
Policy-map class configuration
Command History Release
12.1(8a)EW
Usage Guidelines
This command is not supported on the Supervisor Engine 6-E and Catalyst 4900M chassis.
Use this command to distinguish the quality of service (QoS) trust behavior for certain traffic from other
traffic. For example, inbound traffic with certain DSCP values can be trusted. You can configure a class
map to match and trust the DSCP values in the inbound traffic.
Trust values set with this command supersede trust values set with the qos trust interface configuration
command.
If you specify trust cos, QoS uses the received or default port CoS value and the CoS-to-DSCP map to
generate a DSCP value for the packet.
If you specify trust dscp, QoS uses the DSCP value from the ingress packet. For non-IP packets that are
tagged, QoS uses the received CoS value; for non-IP packets that are untagged, QoS uses the default port
CoS value. In either case, the DSCP value for the packet is derived from the CoS-to-DSCP map.
To return to policy-map configuration mode, use the exit command. To return to privileged EXEC mode,
use the end command.
Catalyst 4500 Series Switch Cisco IOS Command Reference—Release IOS XE 3.3.0SG and IOS 15.1(1)SG)
2-1038
trust [cos | dscp]
no trust [cos | dscp]
(Optional) Classifies an ingress packet by using the packet class of service (CoS)
value. For an untagged packet, the port default CoS value is used.
(Optional) Classifies an ingress packet by using the packet Differentiated Services
Code Point (DSCP) values (most significant 6 bits of 8-bit service-type field). For
a non-IP packet, the packet CoS value is used if the packet is tagged. If the packet
is untagged, the default port CoS value is used to map CoS to DSCP.
Modification
Support for this command was introduced on the Catalyst 4500 series switch.
Chapter 2 Cisco IOS Commands for the Catalyst 4500 Series Switches
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