This setting is the global on/off control for LLDP (Link Layer Discovery Protocol) at the network-element level; when enabled the LLDP agent will receive but not necessarily transmit frames on ports that don't otherwise disable LLDP, and when disabled the agent stops filtering and receiving LLDP frames network-element-wide. An operator uses this to control whether the device participates in neighbor discovery for building an accurate topology map of directly connected equipment. If a technician can't see an expected neighbor in the LLDP neighbor table, checking that this NE-level switch is enabled is an early troubleshooting step.