The Link Layer Discovery Protocol (LLDP) is a standard Layer 2 topology discovery protocol defined in IEEE 802.1ab. LLDP allows a device to send local management information such as management IP address, device ID, and port ID to neighbors. Neighbors save the received information in their management information bases (MIBs). The network management system (NMS) can search required information in MIBs to determine link status.
An NMS must be capable of managing network devices of different types with complex configurations. Most NMSs can detect Layer 3 network topologies, but cannot detect detailed Layer 2 topologies or detection conflicts in configurations. A vendor-neutral protocol is required to exchange Layer 2 information between network devices.
LLDP provides a standard link-layer discovery method. Layer 2 information obtained through LLDP allows the NMS to detect the topology of neighboring devices, and display paths between clients, switches, routers, application servers, and network servers. The NMS can also detect conflicts in configurations between network devices and identify causes of network connection failures. With an NMS, enterprise users can monitor the link status on devices running LLDP and quickly locate network faults.