Cisco 300 Series Cli Manual page 752

Quality of Service (QoS) Commands
OL-32830-01 Command Line Interface Reference Guide
Command Mode
Policy-map Class Configuration mode.
User Guidelines
This command is relevant only when QoS is in advanced, ports-not-trusted mode.
Trust indicates that traffic is sent to the queue according to the packet's QoS
parameters (UP or DSCP).
Use this command to distinguish the 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.
The type of trust is determined in
Trust values set with this command supersede trust values set on specific
interfaces with the qos trust (Interface)
The trust and set commands are mutually exclusive within the same policy map.
Policy maps, which contain set or trust commands or that have ACL classification
to an egress interface, cannot be attached by using the
Configuration mode command.
If specifying trust cos, QoS maps a packet to a queue, the received or default port
CoS value, and the CoS-to-queue map.
Example
The following example creates an ACL, places it into a class map, places the class
map into a policy map and configures the trust state using the DSCP value in the
ingress packet.
switchxxxxxx(config)# ip access-list extended ip1
switchxxxxxx(config-ip-al)#
switchxxxxxx(config-ip-al)#
switchxxxxxx(config)#
switchxxxxxx(config-cmap)#
switchxxxxxx(config-cmap)#
switchxxxxxx(config)#
switchxxxxxx(config-pmap)#
switchxxxxxx(config-pmap-c)#
qos advanced-mode
Interface Configuration mode command.
permit ip any any
exit
class-map c1
match access-group ip1
exit
policy-map p1
class c1
trust cos-dscp
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trust.
service-policy Interface
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