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Configuring LLDP
Overview
In a heterogeneous network, a standard configuration exchange platform ensures that different
types of network devices from different vendors can discover one another and exchange
configuration.
The Link Layer Discovery Protocol (LLDP) is specified in IEEE 802.1AB. The protocol operates on
the data link layer to exchange device information between directly connected devices. With LLDP, a
device sends local device information as TLV (type, length, and value) triplets in LLDP Data Units
(LLDPDUs) to the directly connected devices. Local device information includes its system
capabilities, management IP address, device ID, port ID, and so on. The device stores the device
information in LLDPDUs from the LLDP neighbors in a standard MIB. For more information about
MIBs, see
Network Management and Monitoring Configuration Guide
. LLDP enables a network
management system to quickly detect and identify Layer 2 network topology changes.
Basic concepts
LLDP agent
An LLDP agent is a mapping of an entity where LLDP runs. Multiple LLDP agents can run on the
same interface.
LLDP agents are divided into the following types:
•
Nearest bridge agent.
•
Nearest customer bridge agent.
•
Nearest non-TPMR bridge agent.
A Two-port MAC Relay (TPMR) is a type of bridge that has only two externally-accessible bridge
ports. It supports a subset of the features of a MAC bridge. A TPMR is transparent to all frame-based
media-independent protocols except for the following protocols:
•
Protocols destined to it.
•
Protocols destined to reserved MAC addresses that the relay feature of the TPMR is configured
not to forward.
LLDP exchanges packets between neighbor agents and creates and maintains neighbor information
for them.
shows the neighbor relationships for these LLDP agents. LLDP has two bridge
modes: customer bridge (CB) and service bridge (SB).
Figure 62 LLDP neighbor relationships
