Enabling Auto-Qos For Voip - Cisco Catalyst 3750 Software Configuration Manual

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:
Command
Step 1 configure terminal
Step 2
interface interface-id
Step 3
auto qos voip {cisco-phone | trust}
Step 4
end
Step 5
show auto qos interface interface-id
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 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 on a port and to trust the QoS labels received in inbound
packets when the switch or router connected to a port is a trusted device:
Switch(config)# interface gigabitethernet1/0/1
Switch(config-if)# auto qos voip trust
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Purpose
Enter global configuration mode.
Specify the port that is connected to a Cisco IP phone or the uplink
port that is connected to another switch or router in the interior of the
network, and enter interface configuration mode.
Enable auto-QoS.
The keywords have these meanings:
• cisco-phone—If the port is connected to a Cisco IP phone, the
QoS labels of inbound packets are trusted only when the
telephone is detected.
• trust—The uplink port is connected to a trusted switch or router,
and the VoIP traffic classification in the ingress packet is trusted.
Return to privileged EXEC mode.
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.
Chapter 26 Configuring QoS
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