Voice VLAN

The voice VLAN feature is provided to separate voice traffic from data traffic and assign higher priority to voice traffic, thus decreasing voice transmission delay and jitter.

You can assign or remove a port to or from the voice VLAN manually or have the switch do that dynamically by configuring the automatic voice VLAN assignment mode on the port.

On a port configured with the automatic voice VLAN assignment mode, the switch automatically assigns the port to the voice VLAN when receiving a packet with the source MAC address matching a recognizable voice device vendor OUI. As soon as the port is assigned to the voice VLAN, an aging timer starts. If no recognizable voice traffic has been received before the timer expires, the port is removed from the voice VLAN.

Network Diagram

Figure 1 Network diagram for automatic voice VLAN assignment configuration

Networking and Configuration Requirements

As shown in Figure 1, PC is connected to GigabitEthernet 1/0/1 of Switch A through IP phone 1, and IP phone 2 is connected to GigabitEthernet 1/0/2 of Switch A. IP phone 1 sends out voice traffic with the tag of the voice VLAN, while IP phone 2 sends out voice traffic without any VLAN tag.

Configure the voice VLAN feature to satisfy the following requirements:

l          Configure VLAN 2 as the voice VLAN, and set the aging time of the voice VLAN to 100 minutes. Use VLAN 6 to transmit user service data.

l          GigabitEthernet 1/0/1 and GigabitEthernet 1/0/2 can recognize voice traffic automatically. Service data from PC and voice traffic are assigned to different VLANs and then transmitted to the server and the voice gateway respectively through Switch B.

l          Because the OUI addresses of IP phone 1 and IP phone 2 are not in the default voice device vendor OUI list of the switch, you are required to add their OUI addresses 000f-e200-0000 and 000f-2200-0000 to the OUI list. In addition, configure their descriptions as IP Phone1 and IP Phone2 respectively.

Configuration Example

#

vlan 1 to 2

#

vlan 6

#

interface GigabitEthernet1/0/1

 port link-type trunk

 port trunk permit vlan 1 6

 port trunk pvid vlan 6

 voice vlan enable

#

interface GigabitEthernet1/0/2

 port access vlan 2

 undo voice vlan mode auto

 voice vlan enable

#

 voice vlan aging 100

 voice vlan mac-address 000f-2200-0000 mask ffff-ff00-0000 description IP Phone2

 voice vlan mac-address 000f-e200-0000 mask ffff-ff00-0000 description IP Phone1

 voice vlan 2 enable

Configuration Guidelines

By default, the system maintains the OUI list shown in Table 1-1. You can remove or modify these pre-defined OUI addresses as needed.

Table 1-1 Default OUI addresses preconfigured on the switch

No.	OUI Address	Vendor
1	0001-e300-0000	Siemens phones
2	0003-6b00-0000	Cisco phones
3	0004-0d00-0000	Avaya phones
4	00d0-1e00-0000	Pingtel phones
5	0060-b900-0000	Philips/NEC phones
6	00e0-7500-0000	Polycom phones
7	00e0-bb00-0000	3com phones

l          To use a VLAN as a protocol VLAN and the voice VLAN at the same time, ensure that the voice VLAN assignment mode on the port to be associated with the protocol VLAN is not automatic mode. In automatic mode, the port cannot be assigned to the voice VLAN manually and thus can cause your attempt to associate the protocol VLAN with the port to fail.

l          You cannot set the voice VLAN as the default VLAN on a port in automatic voice VLAN assignment mode.

l          The switch supports only one voice VLAN.

l          Only a static VLAN can be configured as the voice VLAN.

l          In the voice VLAN operating in security mode, the device allows only the packets whose source address matches a recognizable voice device vendor OUI to pass through. All other packets, including authentication packets such as 802.1x authentication packets, will be dropped. Therefore, you are discouraged to transmit both voice and data in the voice VLAN at the same time. If that is needed, disable the security mode of the voice VLAN first.