This setting controls how the device populates its LLDP remote-neighbor table for a port -- from received LLDP messages, from a single learned MAC address in the switch's forwarding database, from both sources, or by automatically choosing based on whether LLDP frames are actually seen. An admin uses autoDetect on most ports so the switch gracefully falls back to MAC-address-based neighbor identification for non-LLDP-speaking devices, while forcing lldpOnly on ports where only standards-compliant LLDP neighbors should ever be recognized. Setting this to macOnly(2) on a port would make the switch identify its neighbor there purely from a single learned MAC address in its forwarding database, ignoring any LLDP frames received.