166connected to the IP phone is added to the VLAN assigned to the IP phone as an tagged member andadded to the VLAN assigned to the host as a untagged member. Also, the LLDP-MED TLVs that the devicesends to the IP phone carry information about the VLAN assigned to the IP phone, so that the voicepackets sent out of the IP phone can be forwarded in the server-assigned VLAN with tags.The EAPOL packets defined in the 802.1X protocol do not carry VLAN tags. When the server isconfigured to assign a tagged VLAN to the IP phone, you must configure the port connected to the IPphone to send 802.1X protocol packets without tags by using the dot1x eapol untag command.Only 802.1X supports assigning tagged VLANs.Figure 54 Using 802.1X to authenticate an IP phoneDisplaying and maintaining voice VLANTask Command RemarksDisplay the voice VLAN state. display voice vlan state [ | { begin | exclude |include } regular-expression ] Available in any viewDisplay the OUI addresses that thesystem supports.display voice vlan oui [ | { begin | exclude |include } regular-expression ] Available in any viewVoice VLAN configuration examplesAutomatic voice VLAN mode configuration exampleNetwork requirementsAs shown in Figure 55,• The MAC address of IP phone A is 0011-1100-0001. The phone connects to a downstream devicenamed PC A whose MAC address is 0022-1100-0002 and to Ethernet 1/0/1 on an upstreamdevice named Device A.• The MAC address of IP phone B is 0011-2200-0001. The phone connects to a downstream devicenamed PC B whose MAC address is 0022-2200-0002 and to Ethernet 1/0/2 on Device A.• Device A uses voice VLAN 2 to transmit voice packets for IP phone A and uses voice VLAN 3 totransmit voice packets for IP phone B.• Configure Ethernet 1/0/1 and Ethernet 1/0/2 to operate in automatic voice VLAN assignmentmode. In addition, if one of them has not received any voice packet in 30 minutes, the port isremoved from the corresponding voice VLAN automatically.
