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Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
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Chapter 11 Configuring Cisco IP Phone Support
Configuring Cisco IP Phone Support
• You cannot configure 10/100 Mbps ports with QoS port architecture 1p4t/2q2t to trust received
Layer 2 CoS values. Configure policies to trust the Layer 3 IP precedence value on switching
modules with QoS port architecture 1p4t/2q2t.
• The following conditions indicate that the Cisco IP Phone and a device attached to the
Cisco IP Phone are in the same VLAN and must be in the same IP subnet:
–
If they both use 802.1p or untagged frames
–
If the Cisco IP Phone uses 802.1p frames and the device uses untagged frames
–
If the Cisco IP Phone uses untagged frames and the device uses 802.1p frames
–
If the Cisco IP Phone uses 802.1Q frames and the voice VLAN is the same as the access VLAN
• The Cisco IP Phone and a device attached to the Cisco IP Phone cannot communicate if they are in
the same VLAN and subnet but use different frame types, because traffic between devices in the
same subnet is not routed (routing would eliminate the frame type difference).
• You cannot use Cisco IOS software commands to configure the frame type used by traffic sent from
a device attached to the access port on the Cisco IP Phone.
• If you enable port security on a port configured with a voice VLAN and if there is a PC connected
to the Cisco IP Phone, set the maximum allowed secure addresses on the port to at least 3.
• You cannot configure static secure MAC addresses in the voice VLAN.
• Ports configured with a voice VLAN can be secure ports (refer to Chapter 26, “Configuring Port
Security”).
• In all configurations, the voice traffic carries a Layer 3 IP precedence value (the default is 5 for voice
traffic and 3 for voice control traffic).
Configuring Cisco IP Phone Support
These sections describe how to configure Cisco IP Phone support:
• Configuring Voice Traffic Support, page 11-5
• Configuring Data Traffic Support, page 11-7
• Configuring Inline Power Support, page 11-8
Note Voice VLANs are referred to as auxiliary VLANs in the Catalyst software publications.

Configuring Voice Traffic Support

To configure the way in which the Cisco IP Phone transmits voice traffic, perform this task:
Command Purpose
Step 1 Router(config)# interface fastethernet slot/port Selects the port to configure.
Step 2 Router(config-if)# switchport voice vlan
{voice_vlan_ID | dot1p | none | untagged}
Configures the way in which the Cisco IP Phone
transmits voice traffic.
Router(config-if)# no switchport voice vlan Clears the configuration.