Default Cisco Ip Phone Support Configuration - Cisco 7604 Configuration Manual

Chapter 16 Configuring Cisco IP Phone Support

Default Cisco IP Phone Support Configuration

Cisco IP phone support is disabled by default.
When the voice VLAN feature is enabled, all untagged traffic is sent with the default CoS priority of the
port.
The CoS is not trusted for 802.1P or 802.1Q tagged traffic.
Cisco IP Phone Support Configuration Guidelines and
Restrictions
The following guidelines and restrictions apply when configuring Cisco IP phone support:
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You must enable the Cisco Discovery Protocol (CDP) on the Cisco 7600 series router port connected
to the Cisco IP phone to send configuration information to the Cisco IP phone.
You can configure a voice VLAN only on a Layer 2 LAN port.
You can configure the ports on WS-X6548-RJ-45 and WS-X6548-RJ-21 switching modules to trust
received Layer 2 CoS values (QoS port architecture 1p1q0t/1p3q1t). The WS-X6548-RJ-45 and
WS-X6548-RJ-21 switching modules cannot supply power to Cisco IP phones.
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
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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 2.
You cannot configure static secure MAC addresses in the voice VLAN.
Ports configured with a voice VLAN can be secure ports (refer to
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).
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
Default Cisco IP Phone Support Configuration
Chapter 47, "Configuring Port
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