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1 LLDP Configuration
When configuring LLDP, go to these sections for information you are interested in:
z Introduction to LLDP
z LLDP Configuration Task List
z Performing Basic LLDP Configuration
z Configuring the Encapsulation Format for LLDPDUs
z Configuring the Encapsulation Format of the Management Address
z Configuring CDP Compatibility
z Configuring LLDP Trapping
z Displaying and Maintaining LLDP
z LLDP Configuration Examples
Introduction to LLDP
Overview
The Link Layer Discovery Protocol (LLDP) operates on the data link layer. It stores and maintains
information about the local device and the devices directly connected to it for network administrators to
manage networks through NMS (network management systems). In LLDP, device information is
encapsulated in LLDPDUs in the form of TLV (meaning type, length, and value) triplets and is
exchanged between directly connected devices. Information in LLDPDUs received is stored in standard
MIB (management information base).
LLDP Fundamental
LLDP operating mode
LLDP can operate in one of the following modes.
z TxRx mode. A port in this mode sends and receives LLDPDUs.
z Tx mode. A port in this mode only sends LLDPDUs.
z Rx mode. A port in this mode only receives LLDPDUs.
z Disable mode. A port in this mode does not send or receive LLDPDUs.
LLDP is initialized when an LLDP-enabled port changes to operate in another LLDP operating mode. To
prevent LLDP from being initialized too frequently, LLDP undergoes a period before being initialized on
an LLDP-enabled port when the port changes to operate in another LLDP operating mode. The period
is known as initialization delay, which is determined by the re-initialization delay timer.
Sending LLDPDUs
An LLDP-enabled device operating in TxRx mode or Tx mode sends LLDPDUs to its directly connected
devices periodically. It also sends LLDPDUs when the local configuration changes to inform the
neighboring devices of the change timely. In any of the two cases, an interval exists between two
successive operations of sending LLDPDUs. This prevents the network from being overwhelmed by
LLDPDUs even if the LLDP operating mode changes frequently.
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