1-11 LLDP ConfigurationWhen configuring LLDP, go to these sections for information you are interested in:z Introduction to LLDPz LLDP Configuration Task Listz Performing Basic LLDP Configurationz Configuring the Encapsulation Format for LLDPDUsz Configuring the Encapsulation Format of the Management Addressz Configuring CDP Compatibilityz Configuring LLDP Trappingz Displaying and Maintaining LLDPz LLDP Configuration ExamplesIntroduction to LLDPOverviewThe Link Layer Discovery Protocol (LLDP) operates on the data link layer. It stores and maintainsinformation about the local device and the devices directly connected to it for network administrators tomanage networks through NMS (network management systems). In LLDP, device information isencapsulated in LLDPDUs in the form of TLV (meaning type, length, and value) triplets and isexchanged between directly connected devices. Information in LLDPDUs received is stored in standardMIB (management information base).LLDP FundamentalLLDP operating modeLLDP 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. Toprevent LLDP from being initialized too frequently, LLDP undergoes a period before being initialized onan LLDP-enabled port when the port changes to operate in another LLDP operating mode. The periodis known as initialization delay, which is determined by the re-initialization delay timer.Sending LLDPDUsAn LLDP-enabled device operating in TxRx mode or Tx mode sends LLDPDUs to its directly connecteddevices periodically. It also sends LLDPDUs when the local configuration changes to inform theneighboring devices of the change timely. In any of the two cases, an interval exists between twosuccessive operations of sending LLDPDUs. This prevents the network from being overwhelmed byLLDPDUs even if the LLDP operating mode changes frequently.
