Cisco WS-C2960-24TC-S Software Guide - Page 299

Configuring Voice VLAN, Default Voice VLAN Configuration, Voice VLAN Configuration Guidelines

Page 299 highlights

Chapter 14 Configuring Voice VLAN Configuring Voice VLAN Note Untagged traffic from the device attached to the Cisco IP Phone passes through the phone unchanged, regardless of the trust state of the access port on the phone. Configuring Voice VLAN These sections contain this configuration information: • Default Voice VLAN Configuration, page 14-3 • Voice VLAN Configuration Guidelines, page 14-3 • Configuring a Port Connected to a Cisco 7960 IP Phone, page 14-4 Default Voice VLAN Configuration The voice VLAN feature is disabled by default. When the voice VLAN feature is enabled, all untagged traffic is sent according to the default CoS priority of the port. The CoS value is not trusted for IEEE 802.1p or IEEE 802.1Q tagged traffic. Voice VLAN Configuration Guidelines These are the voice VLAN configuration guidelines: • You should configure voice VLAN on switch access ports; voice VLAN is not supported on trunk ports. Note Voice VLAN is only supported on access ports and not on trunk ports, even though the configuration is allowed. • The voice VLAN should be present and active on the switch for the IP phone to correctly communicate on the voice VLAN. Use the show vlan privileged EXEC command to see if the VLAN is present (listed in the display). If the VLAN is not listed, see Chapter 12, "Configuring VLANs," for information on how to create the voice VLAN. • 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. If you use the auto-QoS feature, these settings are automatically configured. For more information, see Chapter 28, "Configuring QoS." • You must enable CDP on the switch port connected to the Cisco IP Phone to send the configuration to the phone. (CDP is globally enabled by default on all switch interfaces.) • 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. • If the Cisco IP Phone and a device attached to the phone are in the same VLAN, they must be in the same IP subnet. These conditions indicate that they are in the same VLAN: - They both use IEEE 802.1p or untagged frames. OL-8603-04 Catalyst 2960 Switch Software Configuration Guide 14-3

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14-3
Catalyst 2960 Switch Software Configuration Guide
OL-8603-04
Chapter 14
Configuring Voice VLAN
Configuring Voice VLAN
Note
Untagged traffic from the device attached to the Cisco IP Phone passes through the phone unchanged,
regardless of the trust state of the access port on the phone.
Configuring Voice VLAN
These sections contain this configuration information:
Default Voice VLAN Configuration, page 14-3
Voice VLAN Configuration Guidelines, page 14-3
Configuring a Port Connected to a Cisco 7960 IP Phone, page 14-4
Default Voice VLAN Configuration
The voice VLAN feature is disabled by default.
When the voice VLAN feature is enabled, all untagged traffic is sent according to the default CoS
priority of the port.
The CoS value is not trusted for IEEE 802.1p or IEEE 802.1Q tagged traffic.
Voice VLAN Configuration Guidelines
These are the voice VLAN configuration guidelines:
You should configure voice VLAN on switch access ports; voice VLAN is not supported on
trunk ports.
Note
Voice VLAN is only supported on access ports and not on trunk ports, even though the
configuration is allowed.
The voice VLAN should be present and active on the switch for the IP phone to correctly
communicate on the voice VLAN. Use the
show vlan
privileged EXEC command to see if the
VLAN is present (listed in the display). If the VLAN is not listed, see
Chapter 12, “Configuring
VLANs,”
for information on how to create the voice VLAN.
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. If you use the auto-QoS feature, these settings are
automatically configured. For more information, see
Chapter 28, “Configuring QoS.”
You must enable CDP on the switch port connected to the Cisco IP Phone to send the configuration
to the phone. (CDP is globally enabled by default on all switch interfaces.)
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.
If the Cisco IP Phone and a device attached to the phone are in the same VLAN, they must be in the
same IP subnet. These conditions indicate that they are in the same VLAN:
They both use IEEE 802.1p or untagged frames.