1-6Management addressThe management address of a device is used by the network management system to identify andmanage the device for topology maintenance and network management. The management address isencapsulated in the management address TLV.Operating Modes of LLDPLLDP can operate in one of the following modes:z TxRx mode. A port in this mode sends and receives LLDP frames.z Tx mode. A port in this mode only sends LLDP frames.z Rx mode. A port in this mode only receives LLDP frames.z Disable mode. A port in this mode does not send or receive LLDP frames.Each time the LLDP operating mode of a port changes, its LLDP protocol state machine re-initializes. Toprevent LLDP from being initialized too frequently at times of frequent operating mode change, aninitialization delay, which is user configurable, is introduced. With this delay mechanism, a port mustwait for the specified interval before it can initialize LLDP after the LLDP operating mode changes.How 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:
