Specifications

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Catalyst 2970 Switch Software Configuration Guide
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Chapter 27 Configuring QoS
Configuring Auto-QoS
Enabling Auto-QoS for VoIP
Beginning in privileged EXEC mode, follow these steps to enable auto-QoS for VoIP within a QoS
domain:
To display the QoS commands that are automatically generated when auto-QoS is enabled or disabled,
enter the debug autoqos privileged EXEC command before enabling auto-QoS. For more information,
refer to the “debug autoqos” command in the command reference for this release.
To disable auto-QoS on an interface, use the no auto qos voip interface configuration command. Only
the auto-QoS-generated interface configuration commands for this interface are removed. If this is the
last interface on which auto-QoS is enabled and you enter the no auto qos voip command, auto-QoS is
considered disabled even though the auto-QoS-generated global configuration commands remain (to
avoid disrupting traffic on other interfaces affected by the global configuration). You can use the no mls
qos global configuration command to disable the auto-QoS-generated global configuration commands.
With QoS disabled, there is no concept of trusted or untrusted ports because the packets are not modified
(the CoS, DSCP, and IP precedence values in the packet are not changed). Traffic is switched in
pass-through mode (packets are switched without any rewrites and classified as best effort without any
policing).
This example shows how to enable auto-QoS and to trust the QoS labels received in incoming packets
when the switch or router connected to Gigabit Ethernet interface 0/1 is a trusted device:
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# auto qos voip trust
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface interface-id Enter interface configuration mode, and specify the interface that is
connected to a Cisco IP Phone or the uplink interface that is
connected to another switch or router in the interior of the network.
Step 3
auto qos voip {cisco-phone | trust} Enable auto-QoS.
The keywords have these meanings:
• cisco-phone—If the interface is connected to a Cisco IP Phone,
the QoS labels of incoming packets are trusted only when the
telephone is detected.
• trust—The uplink interface is connected to a trusted switch or
router, and the VoIP traffic classification in the ingress packet is
trusted.
Step 4
end Return to privileged EXEC mode.
Step 5
show auto qos interface interface-id Verify your entries.
This command displays the initial auto-QoS configuration that was
applied; it does not display any user changes to the configuration that
might be in effect. You can use the show running-config privileged
EXEC command to display the auto-QoS configuration and the user
modifications.