Owner's Manual

QoS Commands 313
trust
The trust policy-map class configuration command configures the trust state. The trust state
selects the value QoS uses as the source of the internal DSCP value from the packet. To return to
the default trust state, use the
no form of this command.
Syntax
trust [ cos | dscp | tcp-udp-port ]
no trust
• cos —QoS sets the queue according to CoS to Queue Map.
•
dscp —QoS derives the internal DSCP value by using the DSCP value from the ingress
packet.
•
tcp-udp-port —QoS derives the internal DSCP value by using the destination port value
from the ingress packet, and the tcp-udp-port-to-DSCP-map.
Default Configuration
By default, the port is not trusted. If the trust keyword is alone then the default value is dscp .
Command Mode
Policy-map Class Configuration mode
User Guidelines
This command is used to distinguish the quality of service (QoS) trust behavior for certain
traffic from others. For example, incoming traffic with certain DSCP values can be trusted. A
class-map can be configured to match and trust the DSCP values in the incoming traffic.
NOTE: Policy-maps that contain set or trust commands, or have ACL classification, cannot be attached
to an egress interface by using the service-policy interface configuration command.
Trust values set with this command supersede trust values set on specific interfaces with the
qos trust (Interface)
interface configuration command.
If specifying
trust cos , QoS maps a packet to a queue using the received or default port CoS
value and the CoS-to-queue map.
If specifying
trust dscp , QoS maps the packet by using the DSCP value from the ingress
packet.
If specifying
tcp-udp-port , QoS maps the packet to a queue by using the TCP\UDP port
value from the ingress packet and the tcp-udp-port-to-queue map.