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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
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Chapter 39 Configuring QoS
Configuring Auto-QoS
To display the QoS commands that are automatically generated when auto-QoS is enabled or disabled,
enter the debug auto qos privileged EXEC command before enabling auto-QoS. For more information,
see the debug autoqos command in the command reference for this release.
To disable auto-QoS on a port, use the no auto qos voip interface configuration command. Only the
auto-QoS-generated interface configuration commands for this port are removed. If this is the last port
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 ports 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 a port is a trusted device:
Switch(config)# interface gigabitethernet2/0/1
Switch(config-if)# auto qos voip trust
Auto-QoS Configuration Example
This section describes how you could implement auto-QoS in a network, as shown in Figure 39-14. For
optimum QoS performance, enable auto-QoS on all the devices in the network.