The IEEE 802.1ab Link Layer Discovery Protocol (LLDP) standard defines protocol and management elements suitable for advertising information to stations attached to the same IEEE 802 LAN. The protocol facilitates the identification of stations connected by IEEE 802 LANs or MANs, their points of interconnection, and access points for management protocols.
The LLDP helps the network operators to discover topology information. This information is used to detect and resolve network problems and inconsistencies in the configuration.
The following list is the information included in the protocol defined by the IEEE 802.1ab standard:
Connectivity and management information about the local station to adjacent stations on the same IEEE 802 LAN is advertised.
Network management information from adjacent stations on the same IEEE 802 LAN is received.
Operates with all IEEE 802 access protocols and network media.
Network management information schema and object definitions that suitable for storing connection information about adjacent stations is established.
Provides compatibility with a number of MIBs. For more information, see Figure: LLDP internal architecture for a network node.
The following figure shows LLDP internal architecture for a network node.
To detect and address network problems and inconsistencies in the configuration, the network operators can discover the topology information using LLDP. The Standard-based tools address the complex network scenarios where multiple devices from different vendors are interconnected using Ethernet interfaces.
The following figure shows an MPLS network that uses Ethernet interfaces in the core or as an access/handoff interfaces to connect to different kind of Ethernet enabled devices such as service gateway/routers, QinQ switches DSLAMs, or customer equipment.
The topology information of the network in the following figure can be discovered if, IEEE 802.1ab LLDP is running on each of the Ethernet interfaces in network.
