Specifications

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Catalyst 2950 and Catalyst 2955 Switch Command Reference
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Chapter 2 Cisco IOS Commands
auto qos voip
Table 2-2 lists the auto-QoS configuration for the egress queues.
Command Modes Interface configuration
Command History
Usage Guidelines Use this command to configure the QoS that is appropriate for VoIP traffic within the QoS domain. The
QoS domain includes the switch, the interior of the network, and the edge devices that can classify
incoming traffic for QoS.
Use the cisco-phone keyword on ports connected to Cisco IP phones at the edge of the network. The
switch detects the phone through the Cisco Discovery Protocol (CDP) and trusts the QoS labels in
packets received from the phone.
Use the trust keyword on ports connected to the interior of the network. Because it is assumed that traffic
has already been classified by other edge devices, the QoS labels in these packets from the interior of
the network are trusted.
When you enable the auto-QoS feature on the first interface, these automatic actions occur:
• 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
interface is set to trust the QoS label received in the packet. When a Cisco IP phone is absent, the
ingress classification is set to not trust the QoS label in the packet. The egress queues on the
interface are also reconfigured (see Table 2-2).
• When you enter the auto qos voip trust interface configuration command, the ingress classification
on the interface is set to trust the QoS label received in the packet, and the egress queues on the
interface are reconfigured (see Table 2-2).
You can enable auto-QoS on static, dynamic-access, voice VLAN access, and trunk ports.
To display the QoS configuration that is automatically generated when auto-QoS is enabled, enable
debugging before you enable auto-QoS. Use the debug autoqos privileged EXEC command to enable
auto-QoS debugging.
To disable auto-QoS on an interface, use the no auto qos voip interface configuration command. When
you enter this command, the switch changes the auto-QoS settings to the standard-QoS default settings
for that interface.
To disable auto-QoS on the switch, use the no auto qos voip interface configuration command on all
interfaces on which auto-QoS is enabled. When you enter this command on the last interface on which
auto-QoS is enabled, the switch enables pass-through mode.
Table 2-2 Auto-QoS Configuration for the Egress Queues
Egress Queue Queue Number CoS-to-Queue Map Queue Weight
Expedite 4 5 –
80% WRR 3 3, 6, 7 80%
20% WRR 1 0, 1, 2, 4 20%
Release Modification
12.1(12c)EA1 This command was first introduced.