12 VOICE VLAN C ONFIGURATIONVoice VLAN Overview Voice VLANs are VLANs configured specially for voice data stream. By adding theports with voice devices attached to voice VLANs, you can perform QoS (quality ofservice)-related configuration for voice data, ensuring the transmission priority ofvoice data stream and voice quality.Switch 7750 Ethernet switches determine whether a received packet is a voicepacket by checking its source MAC address. If the source MAC addresses ofpackets comply with the organizationally unique identifier (OUI) addressesconfigured by the system, the packets are determined as voice packets andtransmitted in voice VLAN.You can configure an OUI address for voice packets or specify to use the defaultOUI address.n An OUI address is a globally unique identifier assigned to a vendor by IEEE. Youcan determine which vendor a device belongs to according to the OUI addresswhich forms the first 24 bits of a MAC address.The following table shows the five default OUI addresses of a switch.You can create multiple voice VLANs and bind each voice VLAN to a port. In thisway, the voice traffic received by a port can be transmitted in the voice VLANbound to the port. This feature allows you to manage voice traffic flexibly.A voice VLAN can operate in two modes: automatic mode and manual mode. Youcan configure the operation mode for a voice VLAN according to data streampassing through the ports of the voice VLAN.■ In automatic mode: Switch 7750s automatically add a port connecting a IPvoice device to the voice VLAN through learning the source MAC address in theuntagged packet sent by the IP voice device when it is powered on. When theaging time of a port expires, voice ports on which the OUI addresses are notupdated (no voice stream passes) will be automatically removed from the voiceTable 57 Default OUI addresses preset by the switchNumber OUI Address Vendor1 0003-6b00-0000 Cisco phone2 000f-e200-0000 3Com Aolynk phone3 00d0-1e00-0000 Pingtel phone4 00e0-7500-0000 Polycom phone5 00e0-bb00-0000 3com phone
