LLDP must be used together with MIBs. LLDP requires that each device interface be provided with four MIBs. An LLDP local system MIB that stores status information of a local device and an LLDP remote system MIB that stores status information of neighboring devices are the most important. The status information includes the device ID, interface ID, system name, system description, interface description, device capability, and network management address.
Maintains information in the LLDP local system MIB.
Sends LLDP packets to notify neighboring devices of local device status.
Identifies and processes LLDP packets sent by neighboring devices and maintains information in the LLDP remote system MIB.
Sends LLDP alarms to the NMS when detecting changes in information stored in the LLDP local or remote MIB.
The NMS collects and analyzes topology information stored in LLDP local and remote system MIBs on all managed devices and determines the network topology. The information helps rapidly detect and rectify network faults.
LLDP working modes
When the LLDP working mode changes on an interface, the interface initializes the LLDP state machines. To prevent repeatedly initializations caused by frequent working mode changes, the NetEngine 8000 F supports an initial delay on the interface. When the working mode changes on the interface, the interface initializes the LLDP state machines after a configured delay interval elapses.
Principles for sending LLDP packets
After LLDP is enabled on a device, the device periodically sends LLDP packets to neighboring devices. If the configuration is changed on the local device, the device immediately sends LLDP packets to notify neighboring devices of the changes. If information changes frequently, set a delay for an interface to send LLDP packets. After an interface sends an LLDP packet, the interface does not send another LLDP packet until the configured delay time elapses, which reduces the number of LLDP packets to be sent.
Principles for receiving LLDP packets
A device verifies TLVs carried in LLDP packets it receives. If the TLVs are valid, the device saves information about neighboring devices and sets the TTL value carried in the LLDPDU so that the information ages after the TTL expires. If the TTL value carried in a received LLDPDU is 0, the device immediately ages information about neighboring devices.