1-6How LLDP WorksTransmitting LLDP framesAn LLDP-enabled port operating in TxRx mode or Tx mode sends LLDP frames to its directly connecteddevices both periodically and when the local configuration changes. To prevent the network from beingoverwhelmed by LLDP frames at times of frequent local device information change, an interval isintroduced between two successive LLDP frames.This interval is shortened to 1 second in either of the following two cases:z A new neighbor is discovered, that is, a new LLDP frame is received carrying device informationnew to the local device.z The LLDP operating mode of the port changes from Disable/Rx to TxRx or Tx.This is the fast sending mechanism of LLDP. With this mechanism, a specific number of LLDP framesare sent successively at the 1-second interval to help LLDP neighbors discover the local device as soonas possible. Then, the normal LLDP frame transmit interval resumes.Receiving LLDP framesAn LLDP-enabled port operating in TxRx mode or Rx mode checks the TLVs carried in every LLDPframe it receives for validity violation. If valid, the information is saved and an aging timer is set for itbased on the time to live (TTL) TLV carried in the LLDPDU. If the TTL TLV is zero, the information isaged out immediately.Protocols and StandardsThe protocols and standards related to LLDP include:z IEEE 802.1AB-2005, Station and Media Access Control Connectivity Discoveryz ANSI/TIA-1057, Link Layer Discovery Protocol for Media Endpoint DevicesLLDP Configuration Task ListComplete these tasks to configure LLDP:Task RemarksEnabling LLDP RequiredSetting LLDP Operating Mode OptionalSetting the LLDP Re-Initialization Delay OptionalEnabling LLDP Polling OptionalConfiguring the TLVs to Be Advertised OptionalConfiguring the Management Address and Its Encoding Format OptionalSetting Other LLDP Parameters OptionalPerformingBasic LLDPConfigurationSetting an Encapsulation Format for LLDPDUs OptionalConfiguring CDP Compatibility OptionalConfiguring LLDP Trapping Optional
