Restrictions For Voice Vlans; Information About Voice Vlan; Voice Vlans - Cisco Catalyst 2960 series Configuration Manual

Restrictions for Voice VLANs

• Before you enable voice VLAN, we recommend that you enable QoS on the switch by entering the mls
• You must enable CDP on the switch port connected to the Cisco IP Phone to send the configuration to

Restrictions for Voice VLANs

You cannot configure static secure MAC addresses in the voice VLAN.

Information About Voice VLAN

Voice VLANs

The voice VLAN feature enables access ports to carry IP voice traffic from an IP phone. When the switch is
connected to a Cisco 7960 IP Phone, the phone sends voice traffic with Layer 3 IP precedence and Layer 2
class of service (CoS) values, which are both set to 5 by default. Because the sound quality of an IP phone
call can deteriorate if the data is unevenly sent, the switch supports quality of service (QoS) based on IEEE
802.1p CoS. QoS uses classification and scheduling to send network traffic from the switch in a predictable
manner.
The Cisco 7960 IP Phone is a configurable device, and you can configure it to forward traffic with an IEEE
802.1p priority. You can configure the switch to trust or override the traffic priority assigned by a Cisco
IP Phone.
This network configuration is one way to connect a Cisco 7960 IP Phone.
The Cisco IP Phone contains an integrated three-port 10/100 switch. The ports provide dedicated connections
to these devices:
• Port 1 connects to the switch or other voice-over-IP (VoIP) device.
• Port 2 is an internal 10/100 interface that carries the IP phone traffic.
• Port 3 (access port) connects to a PC or other device.
Catalyst 2960-X Switch VLAN Configuration Guide, Cisco IOS Release 15.0(2)EX
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Trunk ports can carry any number of voice VLANs, similar to regular VLANs. The
Note
configuration of voice VLANs is not supported on trunk ports.
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.
the phone. (CDP is globally enabled by default on all switch interfaces.)
Configuring Voice VLANs
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