"The Link Layer Discovery Protocol or LLDP is a vendor-neutral Layer 2 protocol that allows a network device to advertise its identity and capabilities on the local network. The protocol was formally ratified as IEEE standard 802.1AB-2005 in May 2005." - Wikipedia
What is OpenLLDP?
The OpenLLDP project aims to provide a comprehensive implementation of the IEEE standard 802.1AB Link Layer Discovery Protocol. LLDP is an industry standard protocol designed to supplant proprietary Link-Layer protocols such as Extreme's EDP (Extreme Discovery Protocol) and CDP (Cisco Discovery Protocol). The goal of LLDP is to provide an inter-vendor compatible mechanism to deliver Link-Layer notifications to adjacent network devices. The Open Source implementation of LLDP provided by the OpenLLDP project is intended to help foster wider adoption of LLDP.
Check out OpenLLDP in action on Jason's HP ProCurve 1800-24G: