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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
OL-10101-02
Chapter 29 Configuring QoS
Configuring Standard QoS
trusted boundary feature disables the trusted setting on the switch port and prevents misuse of a
high-priority queue. Note that the trusted boundary feature is not effective if the PC and Cisco IP Phone
are connected to a hub that is connected to the switch.
In some situations, you can prevent a PC connected to the Cisco IP Phone from taking advantage of a
high-priority data queue. You can use the switchport priority extend cos interface configuration
command to configure the telephone through the switch CLI to override the priority of the traffic
received from the PC.
Beginning in privileged EXEC mode, follow these steps to configure trusted boundary on a switch port:
When you enter the no mls qos trust interface configuration command, trusted boundary is not disabled.
If this command is entered and the port is connected to a Cisco IP Phone, the port does not trust the
classification of traffic that it receives. To disable trusted boundary, use the no mls qos trust device
interface configuration command
If you enter the mls qos cos override interface configuration command, the port does not trust the
classification of the traffic that it receives, even when it is connected to a Cisco IP Phone.
You cannot enable trusted boundary if auto-QoS is already enabled and vice-versa. If auto-QoS is
enabled and a Cisco IP Phone is absent on a port, the port does not trust the classification of traffic that
it receives.
Table 29-6 lists the port configuration when an IP phone is present or absent.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 cdp enable Enable CDP globally. By default, it is enabled.
Step 3 interface interface-id Specify the interface to be trusted, and enter interface configuration
mode.
Valid interfaces include physical interfaces.
Step 4 cdp enable Enable CDP on the interface. By default, CDP is enabled.
Step 5 mls qos trust device cisco-phone Configure the Cisco IP Phone as a trusted device on the interface.
You cannot enable both trusted boundary and auto-QoS (auto qos
voip interface configuration command) at the same time; they are
mutually exclusive.
Step 6 mls qos trust cos Configure the port trust state to trust the CoS value of the ingress
packet.
By default, the port is not trusted.
Note In software releases earlier than Cisco IOS
Release 12.1(11)EA1, the mls qos trust cos command is
available only when the switch is running the EI.
For more information on this command, see the command reference
for this release.
Step 7 end Return to privileged EXEC mode.
Step 8 show mls qos interface [interface-id]
[policers]
Verify your entries.
Step 9 copy running-config startup-config (Optional) Save your entries in the configuration file.