Configuration Guide Configuring LLDP
If the work mode is set to TxRx, the device can both transmit and receive LLDP packets. If the work mode is set to Rx Only,
the device can only receive LLDP packets. If the work mode is set to Tx Only, the device can only transmit LLDP packets. If
the work mode is disabled, the device cannot transmit or receive LLDP packets.
5.3.2 LLDP Transmission Mechanism
LLDP packets inform peers of their neighbors. When the LLDP transmission mode is cancelled or disabled, LLDP packets
cannot be transmitted to neighbors.
Working Principle
LLDP periodically transmits LLDP packets when working in TxRx or Tx Only mode. When information about the local device
changes, LLDP immediately transmits LLDP packets. You can configure a delay time to avoid frequent transmission of LLDP
packets caused by frequent changes of local information.
LLDP provides two types of packets:
Standard LLDP packet, which contains management and configuration information about the local device.
Shutdown packet: When the LLDP work mode is disabled or the port is shut down, LLDP Shutdown packets will be
transmitted. A Shutdown packet consists of the Chassis ID TLV, Port ID TLV, Time To Live TLV, and End OF LLDP TLV.
TTL in the Time to Live TLV is 0. When a device receives an LLDP Shutdown packet, it considers that the neighbor
information is invalid and immediately deletes it.
When the LLDP work mode is changed from disabled or Rx to TxRx or Tx, or when LLDP discovers a new neighbor (that is, a
device receives a new LLDP packet and the neighbor information is not stored locally), the fast transmission mechanism is
started so that the neighbor quickly learns the device information. The fast transmission mechanism enables a device to
transmit multiple LLDP packets at an interval of 1 second.
Related Configuration
Configuring the LLDP Work Mode
The default work mode is TxRx.
Run the lldp mode txrx or lldp mode tx command to enable the LLDP packet transmission function. Run the lldp mode rx
or no lldp mode command to disable the LLDP packet transmission function.
In order to enable LLDP packet reception, set the work mode to TxRx or Rx Only. If the work mode is set to Rx Only, the
device can only receive LLDP packets.
Configuring the LLDP Transmission Delay
The default LLDP transmission delay is 2 seconds.
Run the lldp timer tx-delay command to change the LLDP transmission delay.
If the delay is set to a very small value, the frequent change of local information will cause frequent transmission of LLDP
packets. If the delay is set to a very large value, no LLDP packet may be transmitted even if local information is changed.
Configuring the LLDP Transmission Interval
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