1-33) On acquiring the voice VLAN ID and NCP address from DHCP Server 1, the IP phonecommunicates with the specified NCP to download software, ignores the IP address assigned byDHCP Server 1, and sends a new DHCP request message carrying the voice VLAN tag to thevoice VLAN.4) After receiving the DHCP request, DHCP Server 2 residing in the voice VLAN assigns a new IPaddress to the IP phone and sends a tagged response message to the IP phone. After the IP phonereceives the tagged response message, it sends voice data packets tagged with the voice VLANtag to communicate with the voice gateway. In this case, the port connecting to the IP phone mustbe configured to allow the packets tagged with the voice VLAN tag to pass.z An untagged packet carries no VLAN tag.z A tagged packet carries the tag of a VLAN.To set an IP address and a voice VLAN for an IP phone manually, just make sure that the voice VLAN IDto be set is consistent with that of the switch and the NCP is reachable to the IP address to be set.How S5600 Series Switches Identify Voice TrafficS5600 series Ethernet switches determine whether a received packet is a voice packet by checking itssource MAC address against an organizationally unique identifier (OUI) list. If a match is found, thepacket is considered as a voice packet. Ports receiving packets of this type will be added to the voiceVLAN automatically for transmitting voice data.You can configure OUI addresses for voice packets or specify to use the default OUI addresses.An OUI address is a globally unique identifier assigned to a vendor by IEEE. You can determine whichvendor a device belongs to according to the OUI address which forms the first 24 bits of a MAC address.S5600 series Ethernet switches support OUI address mask configuration. You can adjust the matchingdepth of MAC address by setting different OUI address masks.The following table lists the five default OUI addresses on S5600 series switches.Table 1-1 Default OUI addresses pre-defined on the switchNumber OUI address Vendor1 0003-6b00-0000 Cisco phones2 000f-e200-0000 H3C Aolynk phones3 00d0-1e00-0000 Pingtel phones4 00e0-7500-0000 Polycom phones
