Friday, March 24

A Deep Dive Into LLDP And LLDP-MED: What You Need To Know

When it comes to networking technologies, there are a variety of acronyms that can be intimidating at first. One such acronym is LLDP (Link Layer Discovery Protocol) and its derivative, LLDP-MED (Media Endpoint Discovery). But don’t let the name scare you — understanding what LLDP and LLDP-MED are and how they work will give you a better understanding of network management. In this blog article, we’ll take a deep dive into the two protocols – what they are, how they work, and how they’re used. We’ll also explore some of the benefits of using them as well as some potential drawbacks. So if you want to learn more about these important networking tools, then read on!

What is LLDP?

LLDP is an industry standard protocol for managing networked devices. It is used to manage and configure equipment on a network, and can be used to troubleshoot problems. LLDP is a layer 2 protocol, which means it runs over the data link layer (layer 2) of the OSI model. LLDP is similar to the Cisco Discovery Protocol (CDP), but LLDP is an open standard while CDP is proprietary to Cisco.

LLDP uses a simple discovery process to find out information about neighboring devices on the network. It sends out periodic announcements, called “Link Layer Discovery Protocol Data Units” (LLDPDUs), which contain information about the device sending the announcement. These announcements are received by neighboring devices, which then store the information in their own LLDP databases. When a device needs information about another device on the network, it can query its database for that device’s LLDP information.

The Link Layer Discovery Protocol Media Endpoint Discovery (LLDP-MED) is an extension of LLPD that adds media-specific capabilities such as automatic detection of network policy configuration, VLAN assignment, and QoS priority setting.

What is LLDP-MED?

LLDP-MED is an extension to the LLDP protocol that was developed to provide a standardized method for exchanging network management information between networked devices. The LLDP-MED extension allows for the exchange of information such as power management, link layer discovery, and inventory data. The LLDP-MED protocol is commonly used in VoIP and IP telephony networks.

The Benefits of LLDP and LLDP-MED

LLDP (Link Layer Discovery Protocol) and LLDP-MED (Media Endpoint Discovery) are two networking protocols that have a lot to offer. They are designed to help network administrators manage and troubleshoot their networks, as well as provide valuable information about the devices on the network. Here are some of the benefits of using these protocols:

1. Better visibility into the network: LLDP and LLDP-MED provide detailed information about the devices on a network, including their capabilities and configuration. This helps administrators get a better understanding of what is happening on the network, and makes it easier to identify and troubleshoot problems.

2. Improved management of VoIP phones: LLDP-MED can be used to automatically configure VoIP phones with the correct settings for optimal performance. This can save a lot of time and effort when deploying or reconfiguring VoIP systems.

3. Easy detection of rogue devices: Because LLDP and LLDP-MED collect information about every device on the network, they can be used to quickly identify rogue devices that may be causing problems. This is especially helpful in large networks where manually checking each device would be impractical.

4. Reduced support costs: By providing more information about the devices on a network, LLDP and LLDP-MED can help reduce the amount of time needed to resolve technical issues. This can lead to significant savings in support costs over time.

The Drawbacks of LLDP and LLDP-MED

LLDP and LLDP-MED each have a few drawbacks that are worth mentioning. For LLDP, one drawback is that it can consume a significant amount of bandwidth on a network. This is because LLDP sends periodic updates (every 30 seconds by default) to all devices on the network, even if there are no changes to report. As a result, LLDP can add unnecessary traffic to busy networks.

Another drawback of LLDP is that it doesn’t provide any security features. This means that malicious users could potentially spoof LLDP packets and inject false information into the network.

For LLDP-MED, one of the biggest drawbacks is that it’s proprietary and not as widely adopted as LLDP. This means that many devices don’t support it and it might not be compatible with your existing network infrastructure. Additionally, LLDP-MED requires more configuration than LLDP, so it can be more difficult to set up and manage.

How to Implement LLDP and LLDP-MED

The Link Layer Discovery Protocol (LLDP) is a vendor-neutral link layer protocol used by network devices to advertise their identity, capabilities, and neighbors on a network. LLDP is an evolution of the older Cisco Discovery Protocol and is standardized by the IEEE.

LLDP-MED is an extension to LLDP that adds support for media endpoints such as IP phones and VoIP gateways. LLDP-MED is standardized by the IEEE 802.1AB working group.

In order to implement LLDP and LLDP-MED on your network, you will need to enable the protocol on each device and configure it with the appropriate settings. Below we will outline the steps necessary to do this.

1) Enable LLDP on each device:

a) For Cisco devices:

i) Enter global configuration mode: conf t

ii) Enter interface configuration mode: int

iii) Enable LLDP: lldp run

b) For HPE/ArubaOS switches:

i) Enable the feature: feature lldp

ii) Configure all ports where LLDP should run: lldp run


LLDP and LLDP-MED are two important protocols for connecting multiple devices together on a local area network. With the help of these protocols, it is possible to easily configure, monitor and troubleshoot the network environment. Understanding more about these protocols can be beneficial when you are dealing with complex networking environments. We hope that this article has helped you better understand what LLDP and LLDP-MED have to offer so that you can make use of them in your own networks going forward.

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