Cisco Systems 4500 Overriding the CoS Priority of Incoming Frames, Configuring Power

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Software Configuration Guide—Release 15.0(2)SG
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Chapter 38 Configuring Voice Interfaces Overriding the CoS Priority of Incoming Frames
Overriding the CoS Priority of Incoming Frames
A PC or another data device can connect to a Cisco 7960 IP Phone port. The PC can generate packets
with an assigned CoS value. You can also use the switch CLI to override the priority of frames arriving
on the phone port from connected devices, and you can set the phone port to accept (trust) the priority
of frames arriving on the port.
To override the CoS priority setting received from the non-voice port on the Cisco 7960 IP Phone,
perform this task:
Configuring Power
The Catalyst 4500 series switch recognizes that it is connected to a Cisco 7960 IP Phone. The
Catalyst 4500 series switch can supply Power over Ethernet (PoE) to the Cisco 7960 IP Phone if there
is no power on the circuit. The Cisco 7960 IP Phone can also be connected to an AC power source and
supply its own power to the voice circuit. If there is power on the circuit, the switch does not supply it.
You can configure the switch not to supply power to the Cisco 7960 IP Phone and to disable the detection
mechanism. For information on the CLI commands that you can use to supply PoE to a Cisco 7960 IP
Phone, see Chapter 11, “Configuring Power over Ethernet.”
Command Purpose
Step 1 Switch# configure terminal Enters configuration mode.
Step 2 Switch(config)# interface {fastethernet |
gigabitethernet} slot/port Specifies the interface to configure.
Step 3 Switch(config-if)# [no] qos trust extend cos 3 Sets the phone port to override the priority received from
the PC or the attached device and forward the received data
with a priority of 3.
Use the no keyword to return the port to its default setting.
Step 4 Switch(config-if)# end Returns to privileged EXEC mode.
Step 5 Switch# show interface {fastethernet |
gigabitethernet} slot/port switchport Verifies the change.