How to Configure Voice Vlan on 3560

Vlans on a Switch 3560 can send and receive voice traffic.

In order to carry IP (Internet Protocol) voice traffic from an IP phone, you must enable the access ports on the switch to carry voice VLAN traffic. When the 3560 switch connects to a Cisco 7960 IP Phone, the IP Phone sends voice traffic using both Layer 3 IP elements and Layer 2 class of service (CoS) values. This makes the voice packets sound the same because the packets have the same design and size. The voice quality can degrade if the packets are uneven. So the 3560 supports quality of service (QoS). It uses two parameters, classification and scheduling, which makes the call packets appear in a predictable manner, and this guarantees voice quality.

Things You'll Need

• Console cable
• Hyperterminal program (see Resources)

Instructions

1. Connect to the switch with a console cable; attach one end of the cable to the PC and the other end to the switch. Go to the icon that appears on the lower-left corner of the Windows taskbar and click "Start." When the menu pops up go to "Programs," select the "HyperTerminal" program to launch. When the switch comes up, you will be in user mode. The editor automatically starts up when the switch starts up.

2. Type "enable" to enter privileged mode. Next, type "Configure Terminal" to enter the global configuration mode. This is where you can make changes to your switch.

3. Type "Interface e0" in order to enter the interface mode, which specifies the interface connected to the IP phone.

4. Type "trust cos." This allows the interface to classify incoming voice packets using class of service priority values (0 to 7, with 7 the highest priority).

5. Type "switchport voice vlan", followed by optional settings: "Vlan-id / dot1p / none / untagged." The Vlan-ID forwards all voice traffic with priority 5. Vlan IDs range from 1 to 4094. Also, the dot1p option applies Vlan0 for voice traffic and native Vlan for data traffic. The options none and untagged allow the IP phone to use its own default configuration to send traffic, while untagged sends untagged voice traffic out the interface (i.e., packets use native Vlan).

6. Type "end" to exit interface mode. Type "show running config" to verify the configuration. Then type "copy run start" to save the configuration.

References

• Cisco: Configuring Voice VLAN
• Pluscom: Configuring Voice VLAN