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Understanding LLDP and LLDP-MED


Link Layer Discovery Protocol (LLDP) is a vendor-neutral link layer protocol used by network devices to advertise the attributes of a device. These attributes contain type, length, and value descriptions and are referred to as TLVs. LLDP supported devices use TLVs to receive and send information to neighboring devices. Details such as configuration information, device capabilities, and device identity can also be advertised by this protocol. MSS supports the following TLVs:

  • Port Description

  • System Name

  • System Description

  • System Capabilities

  • Management address

You can configure the frequency of LLDP updates, the amount of time to hold information before discarding it, and initialization delay time. You can also select the LLDP TLVs to be sent and received.

Link Layer Discovery Protocol-Media Endpoint Discovery (LLDP-MED) is an extension to LLDP that operates between endpoint devices such as IP phones to provide support for voice over IP (VoIP) applications. LLDP-MED endpoints determine the capabilities of a connected device and whether those capabilities are enabled.


LLDP and LLDP-MED cannot operate simultaneously on a network. By default, access points send only LLDP packets until LLDP-MED packets are received from an endpoint device. The access point then sends out LLDP-MED packets until it receives LLDP packets.

LLDP can be configured on both a controller and on an access point. See Configuring a Controller (Configuring LLDP on a Controller) and Configuring Link Layer Discovery Protocol (LLDP) on an Access Point.