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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter15 Configuring Voice VLAN
Understanding Voice VLAN
Figure 15-1 shows one way to connect a Cisco7960 IP Phone.
Figure15-1 Cisco 7960 IP Phone Connected to a Switch
Cisco IP Phone Voice Traffic
You can configure an access port with an attached Cisco IP Phone to use one VLAN for voice traffic and
another VLAN for data traffic from a device attached to the phone. You can configure access ports on
the switch to send Cisco Discovery Protocol (CDP) packets that instruct an attached phone to send voice
traffic to the switch in any of these ways:
In the voice VLAN tagged with a Layer 2 CoS priority value
In the access VLAN tagged with a Layer 2 CoS priority value
In the access VLAN, untagged (no Layer 2 CoS priority value)
Note 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).
3-port
switch
P1 P3
P2
Access
port
Cisco IP Phone 7960
PC
101351
Phone
ASIC