1-8The DLDP down port sends out a RecoverProbe packet, which carries only information about the localport, every two seconds. Upon receiving the RecoverProbe packet, the remote end returns aRecoverEcho packet. Upon receiving the RecoverEcho packet, the local port checks whether neighborinformation in the RecoverEcho packet is the same as the local port information. If they are the same,the link between the local port and the neighbor is considered to have been restored to a bidirectionallink, and the port will transit from Disable state to Active state and re-establish neighborship with theneighbor.Only DLDP down ports can send and process Recover packets, including RecoverProbe packets andRecoverEcho packets. The auto-recovery mechanism does not take effect on ports manually shutdown.DLDP neighbor stateA DLDP neighbor can be in one of the three states described in Table 1-7.Table 1-7 Description on DLDP neighbor statesDLDP neighborstate DescriptionUnknownA neighbor is in this state when it is just detected and is being probed. Noinformation indicating the state of the neighbor is received. A neighbor is inthis state only when it is being probed. It transits to Two way state orUnidirectional state after the probe operation finishes.Two way A neighbor is in this state after it receives response from its peer. This stateindicates the link is a two-way link.UnidirectionalA neighbor is in this state when the link connecting it is detected to be aunidirectional link. After a device transits to this state, the correspondingneighbor entries maintained on other devices are removed.DLDP Configuration Task ListComplete the following tasks to configure DLDP:Task RemarksEnabling DLDP RequiredSetting DLDP Mode OptionalSetting the Interval for Sending Advertisement Packets OptionalSetting the DelayDown Timer OptionalSetting the Port Shutdown Mode OptionalConfiguring DLDP Authentication OptionalResetting DLDP State OptionalNote that:z DLDP takes effects only on Ethernet interfaces.z DLDP can detect unidirectional links only after all links are connected. Therefore, before enablingDLDP, make sure that optical fibers or copper twisted pairs are connected.
