12-5
Catalyst 3750 MetroSwitch Software Configuration Guide
78-15870-01
Chapter 12 Configuring Voice VLAN
Configuring Voice VLAN
This example shows how to configure a port connected to an IP phone to use the CoS value to classify
ingress traffic, to use 802.1P priority tagging for voice traffic, and to use and the default native VLAN
(VLAN 0) to carry all traffic:
Switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# interface gigabitethernet1/0/1
Switch(config-if)# mls qos trust cos
Switch(config-if)# switchport voice vlan dot1p
Switch(config-if)# end
To return the port to its default setting, use the no switchport voice vlan interface configuration
command.
Configuring the Priority of Incoming Data Frames
You can connect a PC or other data device to a Cisco IP Phone port. To process tagged data traffic (in
802.1Q or 802.1P frames), you can configure the switch to send CDP packets to instruct the IP phone
how to send data packets from the device attached to the access port on the Cisco IP Phone. The PC can
generate packets with an assigned CoS value. You can configure the Cisco IP Phone to not change (trust)
or to override (not trust) the priority of frames arriving on the IP phone port from connected devices.
Beginning in privileged EXEC mode, follow these steps to set the priority of data traffic received from
the nonvoice port on the Cisco IP Phone:
Step 4
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 802.1Q priority of 5. Valid VLAN IDs are from
1 to 4094.
• dot1p—Configure the Cisco IP Phone to use 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
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.
Step 5
end Return to privileged EXEC mode.
Step 6
show interfaces interface-id
switchport or
show running-config interface
interface-id
Verify your voice VLAN entries.
Verify your QoS and voice VLAN entries.
Step 7
copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface interface-id Enter interface configuration mode, and specify the interface connected to the
IP phone.
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