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Catalyst 3750 Metro Switch Software Configuration Guide
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Chapter 26 Configuring QoS
Configuring Auto-QoS
Effects of Auto-QoS on the Configuration
When you enable auto-QoS, the switch adds the auto qos voip interface configuration command and the
generated configuration to the running configuration.
The switch applies the auto-QoS-generated commands as if the commands were entered from the CLI.
An existing user configuration can cause the application of the generated commands to fail, or the user
configuration might be overridden by the generated commands. These actions occur without warning. If
all the generated commands are successfully applied, any user-entered configuration that was not
overridden remains in the running configuration. Any user-entered configuration that was overridden can
be retrieved by reloading the switch without saving the current configuration to memory. If the generated
commands are not applied, the previous running configuration is restored.
Auto-QoS Configuration Guidelines
Before configuring auto-QoS, you should be aware of this information:
• In this release, auto-QoS configures the switch only for VoIP with Cisco IP phones.
• To take advantage of the auto-QoS defaults, you should enable auto-QoS before you configure other
QoS commands. If necessary, you can fine-tune the QoS configuration, but we recommend that you
do so only after the auto-QoS configuration is completed. For more information, see the “Effects of
Auto-QoS on the Configuration” section on page 26-33.
• You can enable auto-QoS on static, dynamic-access, voice VLAN access, and trunk ports.
• By default, the CDP is enabled on all ports. For auto-QoS to function properly, do not disable the
CDP.
• Policing is not enabled with auto-QoS. You can manually enable policing, as described in the
“Configuring an Ingress QoS Policy” section on page 26-48.
The switch automatically sets the ingress classification to trust
the CoS value received in the packet on a nonrouted port or to
trust the DSCP value received in the packet on a routed port.
Switch(config-if)# mls qos trust cos
Switch(config-if)# mls qos trust dscp
If you entered the auto qos voip cisco-phone command, the
switch automatically enables the trusted boundary feature,
which uses the CDP to detect the presence or absence of a
Cisco IP phone.
Switch(config-if)# mls qos trust device cisco-phone
Table 26-5 Generated Auto-QoS Configuration (continued)
Description Automatically Generated Command
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