The Link Layer Discovery Protocol (LLDP) is a vendor-neutral link layer protocol used by network devices for advertising their identity, capabilities, and neighbors on an IEEE 802 local area network, principally wired Ethernet. The protocol is formally referred to by the IEEE as Station and Media Access Control Connectivity Discovery specified in IEEE 802.1AB and IEEE 802.3 section 6 clause 79. The OUI sometimes is referred to as the Vendor ID. (The last 24 bits of the MAC address are the device's unique serial number, assigned to the device by the manufacturer.) Short for Organizational Unique Identifier, the first 24 bits of a MAC address for a network-connected device, which indicate the specific vendor for that device. While complex double-fetch DHCP methods are not required when the network switches makes the determination as to which VLAN a device belongs, a DHCP server or Relay is still required on the voice VLAN so that phones are able to receive an IP address. There are other methods that require complex DHCP setups, or statically assigning the VLAN identifier into each phone individually. When the phone boots up, the switch identifies the device as a phone, and associates the phones traffic with the tagged voice VLAN. In either case, the general setup is a default/native/untagged vlan on an interface for the data traffic, and a second tagged VLAN identified as the voice VLAN on the same interface. Verify phone receives DHCP on voice VLAN from voice scope, and calls are able to complete.Setup classification method for devices that are to be considered a phone.Identify the new VLAN as a 'voice' or 'phone' type VLAN.Tag new voice traffic VLAN to ports phones will connect to.Create a new VLAN dedicated for voice traffic.Some switches will use actual LLDP-MED to identify a connected device as a phone, while some often times lower cost switches will simply use the MAC address OUI. Every switch vendor implements this differently, but nearly all managed switches have this feature in one form or another. This is sometimes referred to as a Voice VLAN in switch configurations.

On bootup, the switch can identify the device is a phone using LLDP-MED and can place the device into the correct VLAN automatically. Switch based LLDP-MED or MAC OUI identification is the preferred method to set a phone into a specific VLAN.

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