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Link layer discovery protocol

(also LLDP)

Link layer discovery protocol definition

The link layer discovery protocol (LLDP) is a standardized network protocol used for discovering and identifying devices on a local area network (LAN). LLDP is mostly used in enterprise networking equipment like switches, routers, and wireless access points. It's particularly useful in large and complex networks.

LLDP is designed to help network administrators manage and troubleshoot their networks. It allows a network device, like a switch or a router, to communicate its identity, capabilities, and information about its neighbors. This information is crucial for understanding the layout and connections within a network.

See also: database administration, network administrator, network automation

How LLDP works

  • Network devices equipped with LLDP send out packets, which contain information about themselves. Similarly, these devices listen for the packets sent by other devices on the network.
  • The information exchanged includes device identification, port description, system capabilities, and other management addresses. This data is stored in a local database, accessible by network management systems.
  • LLDP updates this information regularly, ensuring that the network map is always current.

LLDP advantages and disadvantages

LLDP drastically simplifies network management and provides clear visibility of the network's physical topology, making troubleshooting and documentation easier. However, since it only operates at the link layer, it does not provide higher-level network structure information, like IP addressing schemes or routing details.