How can you use LLDP to automate LAN switching configuration?

1 What is LLDP?

LLDP stands for Link Layer Discovery Protocol. It is a standard protocol that allows devices on a LAN to discover and advertise information about themselves and their neighbors. LLDP operates on the data link layer of the OSI model, which means that it can work across different network technologies and vendors. LLDP messages are sent periodically as frames on each port of a device, and they contain various types of information, such as device name, port ID, capabilities, VLAN, power, and management address.

2 Why use LLDP?

LLDP can help you to automate LAN switching configuration in several ways. First, it can provide you with a clear and accurate view of your network topology and device inventory. You can use LLDP to identify and locate devices, ports, and connections on your LAN, and to verify that they are working as expected. Second, it can enable you to configure some parameters automatically based on the information exchanged by LLDP. For example, you can use LLDP to assign VLANs, adjust power settings, or enable security features on your switches and end devices.

3 How to enable LLDP?

To use LLDP to automate LAN switching configuration, you need to enable it on your devices. Most modern switches and routers support LLDP by default, but you may need to activate it manually or check the settings. To enable LLDP on a Cisco switch, you can use the following commands:

switch(config)#lldp run
switch(config)#interface range gigabitEthernet 0/1-24
switch(config-if-range)#lldp transmit
switch(config-if-range)#lldp receive        

These commands will enable LLDP globally on the switch, and on the specified range of ports. You can also use the lldp tlv-select command to specify which types of information you want to send and receive.

4 How to view LLDP information?

Once you have enabled LLDP on your devices, you can view the LLDP information using various commands or tools. To view the LLDP information on a Cisco switch, you can use the following commands:

switch#show lldp
switch#show lldp neighbors
switch#show lldp neighbors detail        

These commands will show you the summary, brief, or detailed information about the LLDP neighbors on each port of the switch. You can also use the show lldp traffic command to view the statistics of the LLDP frames sent and received. Alternatively, you can use a network management tool that supports LLDP, such as Cisco Network Assistant or SolarWinds Network Topology Mapper, to visualize and analyze the LLDP information on your network.

5 How to automate LAN switching configuration with LLDP?

Now that you have enabled and viewed the LLDP information on your devices, you can use it to automate LAN switching configuration tasks. For instance, you can use LLDP to assign VLANs to ports based on the device type or capabilities. The switchport voice vlan command is an example of this on Cisco switches. Additionally, LLDP can be used to adjust power settings of ports based on the device power requirements. The power inline auto command can enable Power over Ethernet (PoE) on a port that connects to a device that supports LLDP and advertises its power class and priority. Finally, LLDP can enable security features on ports based on the device identity or location. The dot1x pae authenticator command is an example of this on Cisco switches, allowing 802.1X authentication on a port that connects to a device that supports LLDP and advertises its MAC address and management address.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?