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
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 configur ation mode
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 Cisc o
IP phones. The switch detects the tele phone through Ci sco Discovery Protoco l (CDP) and trusts those
CoS labels in p ackets th at are received from t he tele phone.
Apply the trust keyword on those ports that are connect ed to the interior of the netw ork. 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 c ommand).
• DBL is enabled globally (qos dbl global configuration c ommand).
• When yo u ente r the auto q os voip cisco-phone inter face configuration command, the trusted
boundary feature is enabled. It uses the Cisco Discovery Protoc ol (CDP) to detect the pres ence or
absence of a Cisco IP phone. When a Cisco IP phone is detected, the ingre ss 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 ingr ess classification is set to not
trust the CoS label in the packet.
• When you enter th e auto qos voip trust interface configuration command, the ingress classification
on the specified interface is set to trust the CoS label that is received in the packet provided the
specified interface is configured as Layer 2 (and is set to trust DSCP if the interface is configured
as Layer 3).
You can enable auto-QoS on static, dynamic -access, voice VLAN access, and trunk ports.
cisco-phone Generates a QoS configuration for Cisco IP phone interfaces (conditional trust
through CDP). T he CoS labels of incom ing p ackets are trus ted onl y 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.