Mls Qos Trust - Cisco Catalyst 2950 Command Reference Manual

Chapter 2 Catalyst 2950 and 2955 Cisco IOS Commands

mls qos trust

Use the mls qos trust interface configuration command to configure the port trust state. Ingress traffic
can be trusted, and classification is performed by examining the class of service (CoS) or the
Differentiated Services Code Point (DSCP) value. Use the no form of this command to return to the
default setting.
Syntax Description cos
cos pass-through
dscp
device cisco-phone
dscp
Defaults The port is not trusted.
Pass-through mode is disabled.
Trusted boundary is disabled.
If no keyword is specified and the switch is running the EI, the default is dscp.
Command Modes Interface configuration
Command History Release
12.1(6)EA2
12.1(11)EA1
Usage Guidelines Packets entering a quality of service (QoS) domain are classified at the edge of the QoS domain. When
the packets are classified at the edge, the switch port within the QoS domain can be configured to one
of the trusted states because there is no need to classify the packets at every switch within the domain.
Use this command to specify whether the port is trusted and which fields of the packet to use to classify
traffic.
When a port is configured with trust DSCP and the incoming packet is a tagged non-IP packet, the CoS
value for the packet is set to 0, and the DSCP-to-CoS map is not applied. For an untagged non-IP packet,
the default port CoS value is used.
OL-10102-01
mls qos trust [cos [pass-through dscp] | device cisco-phone | dscp]
no mls qos trust [cos [pass-through dscp] | device cisco-phone | dscp]
(Optional) Classify ingress packets with packet CoS values. For untagged
packets, the port default CoS value is used.
(Optional) Configure the interface to classify ingress packets by trusting the
CoS value and to send packets without modifying the DSCP value
(pass-through mode).
(Optional) Classify ingress packets by trusting the value sent from the Cisco IP
phone (trusted boundary).
(Optional) Classify ingress packets with packet DSCP values (most significant
6 bits of the 8-bit service-type field). For non-IP packets, the packet CoS value
is set to 0. This keyword is available only if your switch is running the enhanced
software image (EI).
Modification
This command was introduced.
The device cisco-phone and pass-through dscp keywords were added.
Catalyst 2950 and Catalyst 2955 Switch Command Reference
mls qos trust
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