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Catalyst 2960 Switch SoftwareConfiguration Guide
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Chapter14 Configuring Voice VLAN
Configuring Voice VLAN
Configuring IP Phone Voice Traffic
You can configure a port connected to the Cisco IP Phone to send CDP packets to the phone to configure
the way in which the phone sends voice traffic. The phone can carry voice traffic in IEEE 802.1Q frames
for a specified voice VLAN with a Layer 2 CoS value. It can use IEEE 802.1p priority tagging to give
voice traffic a higher priority and forward all voice traffic through the native (access) VLAN. The IP
Phone can also send untagged voice traffic or use its own configuration to send voice traffic in the access
VLAN. In all configurations, the voice traffic carries a Layer 3 IP precedence value (the default is 5).
Beginning in privileged EXEC mode, follow these steps to configure voice traffic on a port:
This example shows how to configure a port connected to an IP Phone t o use the CoS value to classify
incoming traffic, to use IEEE 802.1p priority tagging for voice traffic, and to use the default native
VLAN (VLAN0) to carry all traffic:
Switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# mls qos trust cos
Switch(config-if)# switchport voice vlan dot1p
Switch(config-if)# end
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface interface-id Specify the interface connected to the IP Phone, and enter interface
configuration mode.
Step3 mls qos trust cos Configure the interface to classify incoming traffic packets by using the
packet CoS value. For untagged packets, the port default CoS value is used.
Note Before configuring the port trust state, you must first globally enable
QoS by using the mls qos global configuration command.
Step4 switchport voice vlan {vlan-id |
dot1p | none | untagged}
Configure how the Cisco IP Phone carries voice traffic:
•vlan-id—Configure the Cisco IP Phone to forward all voice traffic
through the specified VLAN. By default, the Cisco IP Phone forwards
the voice traffic with an IEEE 802.1Q priority of 5. Valid VLAN IDs are
1 to 4094.
•dot1p—Configure the Cisco IP Phone to use IEEE 802.1p priority
tagging for voice traffic and to use the default native VLAN (VLAN 0)
to carry all traffic. By default, the Cisco IP Phone forwards the voice
traffic with an IEEE 802.1p priority of 5.
•none—Allow the IP Phone to use its own configuration to send
untagged voice traffic.
•untagged—Configure the phone to send untagged voice traffic.
Step5 end Return to privileged EXEC mode.
Step6 show interfaces interface-id
switchport or
show running-config interface
interface-id
Verify your voice VLAN entries.
Verify your QoS and voice VLAN entries.
Step7 copy running-config startup-config (Optional) Save your entries in the configuration file.