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
auto qos voip
auto qos voip
To automatically configure quality of service (auto-QoS) for voice over IP (VoIP) within a QoS domain,
use the auto qos voip interface configuration command. To change the auto-QoS configuration settings
to the standard QoS defaults, use the no form of this command.
auto qos voip {cisco-phone | trust}
no auto qos voip {cisco-phone | trust}
Syntax Description
Defaults Auto-QoS is disabled on all interfaces
Command Modes Interface configuration mode
Command History
Usage Guidelines Use this command to configure a QoS that is appropriate for VoIP traffic within the QoS domain, which
includes the switch, the interior of the network, and the edge devices that can classify incoming traffic
for QoS.
Apply the cisco-phone keyword on those ports (at the edge of the network) that are connected to Cisco
IP phones. The switch detects the telephone through Cisco Discovery Protocol (CDP) and trusts those
CoS labels in packets that are received from the telephone.
Apply the trust keyword on those ports that are connected to the interior of the network. Assume that
the traffic has already been classified by the other edge devices. So, the CoS/DSCP labels in these
packets are trusted.
When you enable the auto-QoS feature on the specified interface, these actions automatically occur:
• QoS is globally enabled (qos global configuration command).
• DBL is enabled globally (qos dbl global configuration command).
• When you enter the auto qos voip cisco-phone interface configuration command, the trusted
boundary feature is enabled. It uses the Cisco Discovery Protocol (CDP) to detect the presence or
absence of a Cisco IP phone. When a Cisco IP phone is detected, the ingress classification on the
specific interface is set to trust the CoS label that is received in the packet because some older
phones do not mark DSCP. When a Cisco IP phone is absent, the ingress classification is set to not
trust the CoS label in the packet.
cisco-phone Generates a QoS configuration for Cisco IP phone interfaces (conditional trust
through CDP). The CoS labels of incoming packets are trusted only when a
telephone is detected.
trust Connects the interface to a trusted switch or router and automatically configures
QoS for VoIP. The CoS and DSCP labels of incoming packets are trusted.
Release Modification
12.1(19)EW Support for this command was introduced on the Catalyst 4500 series switch.

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