Cisco Catalyst 4500 Series Command Reference Guide

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Catalyst 4500 Series Switch Cisco IOS Command Reference—Release IOS XE 3.4.0SG and IOS 15.1(2)SG)
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Chapter 2 Cisco IOS Commands for the Catalyst 4500 Series Switches
qos trust
qos trust
To set the trusted state of an interface (for example, whether the packets arriving at an interface are
trusted to carry the correct CoS, ToS, and DSCP classifications), use the qos trust command. To set an
interface to the untrusted state, use the no form of this command.
qos trust {cos | device cisco-phone | dscp | extend [cos priority]}
no qos trust {cos | device cisco-phone | dscp | extend [cos priority]}
Syntax Description
Defaults The default settings are as follows:
• If global QoS is enabled, trust is disabled on the port.
• If global QoS is disabled, trust DSCP is enabled on the port.
• The CoS priority level is 0.
Command Modes Interface configuration mode
Command History
Usage Guidelines This command is not supported on the Supervisor Engine 6-E and Catalyst 4900M chassis.
You can only configure the trusted state on physical LAN interfaces.
By default, the trust state of an interface when QoS is enabled is untrusted; when QoS is disabled on the
interface, the trust state is reset to trust DSCP.
When the interface trust state is qos trust cos, the transmit CoS is always the incoming packet CoS (or
the default CoS for the interface, if the packet is not tagged).
When the interface trust state is not qos trust dscp, the security and QoS ACL classification will always
use the interface DSCP and not the incoming packet DSCP.
cos Specifies that the CoS bits in incoming frames are trusted and derives the
internal DSCP value from the CoS bits.
device cisco-phone Specifies the Cisco IP phone as the trust device for a port.
dscp Specifies that the ToS bits in the incoming packets contain a DSCP value.
extend Specifies to extend the trust to Port VLAN ID (PVID) packets coming from
the PC.
cos priority (Optional) Specifies that the CoS priority value is set to PVID packets; valid
values are from 0 to 7.
Release Modification
12.1(8a)EW Support for this command was introduced on the Catalyst 4500 series switch.
12.1(11)EW Support for extending trust for voice was added.
12.1(19)EW Support for trust device Cisco IP phone was added.

Cisco Catalyst 4500 Series Specifications

General

Series	Catalyst 4500 Series
Category	Switch
Layer Support	Layer 2, Layer 3
Form Factor	Modular chassis
Stackable	No
Chassis Slots	3, 6, 7, 10
Power Supply Options	AC, DC
Redundancy	Power supply, Supervisor engine
Network Management	Cisco IOS Software CLI, SNMP, Cisco Prime Infrastructure
Features	Security, QoS
Port Density	Up to 384 ports per chassis
Security Features	802.1X, ACLs, DHCP Snooping, Dynamic ARP Inspection, IP Source Guard
Supervisor Engine	8-E