Specifications

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Catalyst 4500 Se ries S wit ch C is co IO S C om mand R efer ence —Re lease I OS XE 3 .3.0 XO(1 5.1 (1)XO)
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Chapter 2 Cisco IOS Commands for the Catalyst 4500 Series Switches
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 .
trust [cos | dscp]
no trust [cos | dscp]
Syntax Description
Defaults The action is not trus ted.
Command Modes Policy-map class configuration
Usage Guidelines 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 valu es 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 tr ust 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 va lue from the ingress pa cket. For non-IP pac kets 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 configur ation mode , use the exit command. To return to privileged EXEC mode,
use the end command.
Examples This example shows how to define a port trust state to trust inbound DSCP values for traffic classified
with “class1”:
Switch# configure terminal
Switch(config)# policy-map policy1
Switch(config-pmap)# class class1
Switch(config-pmap-c)# trust dscp
Switch(config-pmap-c)# police 1000000 20000 exceed-action policed-dscp-transmit
Switch(config-pmap-c)# exit
Switch#
cos (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.
dscp (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.