119Voice VLAN configurationThis chapter includes these sections:• Overview• Configuring a voice VLAN• Displaying and maintaining voice VLAN• Voice VLAN configuration examplesOverviewAs voice communication technologies grow more mature, voice devices are more and more widelydeployed, especially on broadband networks, where voice traffic and data traffic often co-exist. Usually,compared to data traffic, voice traffic is given a higher transmission priority for the purpose of reducingtransmission delay and packet loss.A voice VLAN is configured especially for voice traffic. After assigning the ports connecting to voicedevices to a voice VLAN, the system automatically configures quality of service (QoS) parameters forvoice traffic, improving the transmission priority of voice traffic and ensuring voice quality.Common voice devices include IP phones and integrated access devices (IADs). Only IP phones are usedin the voice VLAN configuration examples in this chapter.When an IP phone accesses a device, the device must have completed the following tasks:• Identifying the IP phone and obtaining the MAC address of the IP phone, so that the device canperform security authentication for the IP phone and increase the priority for voice traffic.• Advertising the voice VLAN information to the IP phone, so that the IP phone can automaticallyconfigure the voice VLAN according to the received information and the voice packets sent out ofthe IP phone can be transmitted within the voice VLAN.Methods of identifying IP phonesOUI addressesA device determines whether a received packet is a voice packet by checking its source MAC address.A packet whose source MAC address complies with the voice device's Organizationally UniqueIdentifier (OUI) address is regarded as voice traffic.You can configure the OUI addresses of a device in advance or use the default OUI addresses. Table 14lists the default OUI address for each vendor's devices. The switch supports 128 OUI addresses.Table 14 The default OUI addresses of different vendorsNumber OUI address Vendor1 0001-e300-0000 Siemens phone2 0003-6b00-0000 Cisco phone
