Mls Qos Trust - Cisco Catalyst 3550 Command Reference Manual

Chapter 2 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 Differentiated Services Code Point
(DSCP), class of service (CoS), or IP-precedence packet field. Use the no form of this command to
return a port to its untrusted state.
Syntax Description cos
cos pass-through
dscp
device cisco-phone
dscp
dscp pass-through
cos
ip-precedence
Defaults
The port is not trusted. If no keyword is specified when the command is entered, the default is dscp.
Command Modes
Interface configuration
Command History Release
12.1(4)EA1
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.
78-11195-09
mls qos trust [cos [pass-through dscp] | device cisco-phone | dscp [pass-through cos] |
ip-precedence]
no mls qos trust [cos [pass-through] | device | dscp [pass-through] | ip-precedence]
(Optional) Classify ingress packets with packet CoS values. For untagged
packets, use the port default CoS value.
(Optional) Classify ingress packets by trusting the CoS value and by sending
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 8-bit service-type field). For non-IP packets, the packet CoS is used
if the packet is tagged. The default port CoS value is used if the packet is
untagged.
(Optional) Classify ingress packets by trusting the DSCP value and by sending
packets without modifying the CoS value (pass-through mode).
(Optional) Classify ingress packets with IP-precedence values (most
significant 3 bits of 8-bit service-type field). For non-IP packets, the packet
CoS is used if the packet is tagged. The port default CoS value is used if the
packet is untagged.
Modification
This command was first introduced.
The device cisco-phone, pass-through cos, and pass-through dscp
keywords were added.
Catalyst 3550 Multilayer Switch Command Reference
mls qos trust
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