Chapter 12 Configuring Voice Vlan; Understanding Voice Vlan - Cisco Catalyst 3750 Software Configuration Manual

Configuring Voice VLAN
This chapter describes how to configure the voice VLAN feature on the Catalyst 3750 Metro switch.
Voice VLAN is also referred to as an auxiliary VLAN in some Catalyst 6500 family switch
documentation.
For complete syntax and usage information for the commands used in this chapter, refer to the command
Note
reference for this release.
This chapter consists of these sections:
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Understanding Voice VLAN

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 IP 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. For more information on QoS, see
The Cisco 7960 IP Phone is a configurable device, and you can configure it to forward traffic with an
802.1p priority. You can configure the switch to trust or override the traffic priority assigned by an
IP Phone.
The Cisco IP Phone contains an integrated three-port 10/100 switch as shown in
provide dedicated connections to these devices:
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Figure 12-1
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Understanding Voice VLAN, page 12-1
Configuring Voice VLAN, page 12-3
Displaying Voice VLAN, page 12-6
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.
shows one way to connect a Cisco 7960 IP Phone.
C H A P T E R
Chapter 26, "Configuring QoS."
Catalyst 3750 Metro Switch Software Configuration Guide
12
Figure 12-1. The ports
12-1