Exploring The Usefulness Of LLDP-MED: Leveraging Link Layer Discovery Protocol Beyond Networking Basics



Introduction to LLDP-MED

LLDP-MED is an extension to the Link Layer Discovery Protocol (LLDP) that allows for media-specific configuration and management of networked devices. The LLDP-MED specification was developed by the IEEE in order to provide a standard method for managing VoIP devices on a network. LLDP-MED builds upon the existing LLDP specification and adds new TLVs (Type-Length-Values) that are specific to VoIP applications.

In order to understand how LLDP-MED works, it is first necessary to understand the basics of LLDP. LLDP is a layer 2 protocol that is used for discovering neighboring devices on a network and advertising device capabilities. Devices that support LLDP will periodically send out multicast packets containing information about themselves. This information includes the device’s MAC address, IP address, and other capabilities.

When a device receives an LLDP packet from a neighboring device, it will store this information in a database. This database can then be used by system administrators in order to manage the network. For example, if a new VoIP phone is added to the network, the administrator can use the information stored in the database to automatically configure the phone with the correct settings.

LLDP-MED extends this functionality by adding support for media-specific configuration and management. This allows administrators to manage not only networking settings, but also multimedia settings such as audio codecs and video resolutions. In addition, LLDP-MED adds support

The Benefits of LLDP-MED

LLDP-MED (Link Layer Discovery Protocol – Media Endpoint Discovery) is an IEEE 802.1 standard that helps network devices to automatically configure themselves in accordance with the needs of different types of media applications. It does this by exchanging information about their capabilities with other LLDP-MED devices on the network. This allows for a much more efficient and streamlined network deployment, as well as providing greater flexibility in how the network can be used.

Some of the key benefits of LLDP-MED include:

  • Ease of deployment and configuration – LLDP-MED automates many of the tasks associated with setting up and configuring a network, making it much easier and quicker to get up and running.
  • Improved security – By automating the process of configuring networking devices, LLDP-MED reduces the potential for human error which can lead to security vulnerabilities.
  • Greater flexibility – LLDP-MED provides greater flexibility in how a network can be deployed and used, as it is not limited by pre-configured settings. This allows for more customised networks that can better meet the needs of specific applications.
  • Enhanced compatibility – The use of LLDP-MED ensures compatibility between different types of equipment from different vendors, as all devices adhere to the same standards. This eliminates the need for time-consuming manual configuration when adding new devices to an existing network.

The Uses of LLDP-MED

In many cases, LLDP-MED can be used to automatically configure and optimize IP telephony devices such as VoIP phones, IP video cameras, and wireless access points. LLDP-MED can also be used to manage energy-efficient Ethernet (EEE) settings on networked devices. In addition, LLDP-MED can be used to monitor and troubleshoot IP networks.

How LLDP-MED Works

LLDP-MED is an extension to the Link Layer Discovery Protocol (LLDP) that allows for media-specific configuration of network devices. The LLDP-MED specification was developed by the IEEE 802.1 Audio/Video Bridging (AVB) Task Group and defines a set of TLVs (type-length values) that can be used to convey information about the capabilities and settings of audio/video endpoints.

In order to understand how LLDP-MED works, it is first necessary to understand the basics of LLDP. LLDP is a Layer 2 protocol that allows network devices to discovery each other and exchange information about their capabilities. Each device maintains a database of information about the other devices on the network, which is constantly updated as new devices are added or removed. This database can be used by network administrators to troubleshoot connectivity issues, or simply to get an overview of the network topology.

The LLDP-MED extension adds a number of new TLVs that can be used to convey information about audio/video endpoints. These TLVs include things like support for Power over Ethernet (PoE), VLAN settings, and QoS parameters. By including this information in the database maintained by LLDP, AVB capable switches can automatically configure themselves to provide the appropriate level of service for audio/video traffic.

LLDP-MED also defines a set of events that can trigger updates to the database. For example, if

Implementing LLDP-MED

For those not familiar with LLDP-MED, it is an extension to the Link Layer Discovery Protocol (LLDP) that allows for media-specific configuration of network elements. This is useful in VoIP deployments, as it allows for QoS markings to be propagated from the switch to the IP phone. It can also be used for other types of data, such as video or Wireless LANs.

To configure LLDP-MED on a Cisco switch, you will need to first enable the protocol:

lldp run

Once LLDP is enabled, you can then configure various parameters related to it. For example, you can specify what type of medium each port should use:

interface GigabitEthernet0/1

lldp med-type voice


interface GigabitEthernet0/2

lldp med-type video


interface GigabitEthernet0/3

lldp med-type data

You can also specify other parameters, such as the 802.1p priority or DSCP values to be used for each type of traffic. Consult the Cisco documentation for more information on all the available options.


The use of LLDP-MED has proven to be a useful tool for organizations that need to leverage link layer discovery protocol beyond networking basics. It allows them to easily detect and classify devices on the network, as well as configure voice and video applications with ease. With its versatility, scalability, compatibility and increased efficiency, it can help optimize the performance of any organization’s IT infrastructure. By understanding how LLDP-MED works and exploiting its various features, businesses can benefit from enhanced security measures, improved VoIP capabilities and better management of their networks.

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