What does LLDP stand for?
LLDP stands for Link Layer Discovery Protocol. The vendor-neutral IEEE 802.1AB protocol by which devices advertise their identity, port and capabilities to directly connected neighbors; LLDP-MED adds VoIP details such as the voice VLAN. It replaces Cisco's CDP in mixed networks and helps map what is plugged in where.
LLDP is a vendor-neutral protocol, IEEE 802.1AB, that lets network devices tell their directly connected neighbours who they are. Each switch, router, phone or access point regularly sends a small frame out of every port, announcing its name, the port the frame was sent from, its capabilities and its management address. The neighbour stores the information and does not pass the frame on, so every device knows exactly what is at the other end of each cable. Administrators use it to map and document a network and to check cabling.
LLDP in practice: an example
A technician has to find which switch port a wall socket in a meeting room leads to, and the cable labels are missing. She connects a laptop running an LLDP client to the socket. Shortly afterwards it shows the neighbour: switch SW-2F-03, port Gi1/0/17. No cable tracing is needed, and the documentation is corrected.
What LLDP is confused with
LLDP vs CDP: what is the difference?
Cisco Discovery Protocol does the same job but is Cisco's own protocol and runs on Cisco equipment. LLDP is the IEEE standard that works between vendors.
LLDP vs ARP: what is the difference?
ARP finds the MAC address that belongs to an IP address so that a packet can be delivered. LLDP describes the neighbouring device itself: its name, its port and its capabilities. What ARP stands for
Which exams cover LLDP?
LLDP is on the official CompTIA acronym list for one of the four exams covered here.
- Network+ N10-009: 5.0 (Network Troubleshooting).
Each number is a CompTIA exam objective and the name in brackets is its domain. The exam puts the term in a scenario; it does not ask you to recite the expansion.
Check yourself: two practice questions
Written by CertSprint for this page. They are not taken from any exam.
1. A network has switches from three vendors, and the administrator wants each switch to list the device connected to every port. Which protocol should be enabled?
- LLDP
- CDP only
- OSPF
- NTP
Show the answer
A. LLDP. LLDP is the vendor-neutral IEEE standard for discovering neighbours. CDP would cover only the Cisco devices.
2. How far does an LLDP frame travel?
- Only to the directly connected neighbour
- To every device in the VLAN
- To the default gateway and back
- To the DNS server
Show the answer
A. Only to the directly connected neighbour. A device that receives an LLDP frame keeps the information and does not forward the frame, so each device learns only about its direct neighbours.
Sources: IEEE 802.1AB: Station and Media Access Control Connectivity Discovery (LLDP). The acronym and its expansion come from CompTIA's official acronym lists, linked from each exam glossary above. The explanation, example and questions are CertSprint's own, checked against these sources on 12 November 2026.