Voice VLAN Configuration

•Before you enable voice VLAN, we recommend that you enable QoS on the switch by entering the mls qos global configuration command and configure the port trust state to trust by entering the mls qos trust cos interface configuration command.

• The Port Fast feature is automatically enabled when voice VLAN is configured. When you disable voice VLAN, the Port Fast feature is not automatically disabled.

• When you enable port security on an interface that is also configured with a voice VLAN, you must set the maximum allowed secure addresses on the port to at least two.

• If any type of port security is enabled on the access VLAN, dynamic port security is automatically enabled on the voice VLAN.

• You cannot configure static secure or sticky secure MAC addresses on a voice VLAN.
Configuring a Port to Connect to a Cisco 7960 IP Phone

VOICE VLAN CONFIGURATION:

Because a Cisco 7960 IP Phone also supports a connection to a PC or other device, a port connecting the switch to a Cisco 7960 IP Phone can carry mixed traffic.

You can configure the port to carry voice traffic in one of these ways:

• Configuring Ports to Carry Voice Traffic in 802.1Q Frames

• Configuring Ports to Carry Voice Traffic in 802.1P Priority-Tagged Frames
You can configure the IP phone to carry data traffic in one of these ways:

• Overriding the CoS Priority of Incoming Data Frames

• Configuring the IP Phone to Trust the CoS Priority of Incoming Data Frames
switchport voice vlan dot1p :

Instruct the switch port 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.
switchport voice vlan vlan-id

Instruct 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.
switchport priority extend cos value :

Set the IP phone access port to override the priority received from the PC or the attached device.
The CoS value is a number from 0 to 7. Seven is the highest priority. The default is 0.

switchport priority extend trust
Set the IP phone access port to trust the priority received from the PC or the attached device.