Operation Manual – DLDPH3C S5600 Series Ethernet Switches Chapter 1 DLDP Configuration1-6Table 1-4 Processing procedure when no echo packet is received from the neighborNo echo packet received fromthe neighbor Processing procedureIn normal mode, no echo packet isreceived when the echo waitingtimer expires.In enhanced mode, no echo packetis received when the enhancedtimer expiresDLDP switches to the disable state, outputslog and tracking information, and sends flushpackets. Depending on the user-definedDLDP down mode, DLDP disables the localport automatically or prompts you to disablethe port manually. DLDP sends RSYmessages and removes the correspondingneighbor entries.1.2.2 DLDP StatusA link can be in one of these DLDP states: initial, inactive, active, advertisement, probe,disable, and delaydown.Table 1-5 DLDP statusStatus DescriptionInitial Initial status before DLDP is enabled.Inactive DLDP is enabled but the corresponding link is downActive DLDP is enabled, and the link is up or an neighbor entry is clearedAdvertisementAll neighbors communicate normally in both directions, or DLDPremains in active state for more than five seconds and enters thisstatus. It is a stable state where no unidirectional link is foundProbeDHCP sends packets to check whether the link is a unidirectional.It enables the probe sending timer and an echo waiting timer foreach target neighbor.DisableDLDP detects a unidirectional link, or finds (in enhanced mode)that a neighbor disappears. In this case, DLDP sends andreceives only recover probe packets and recover echo packets.DelayDownWhen a device in the active, advertisement, or probe DLDP statereceives a port down message, it does not removes thecorresponding neighbor immediately, neither does it changes tothe inactive state. Instead, it changes to the delaydown state first.When a device changes to the delaydown state, the related DLDPneighbor information remains, and the DelayDown timer istriggered. After the DelayDown timer expires, the DLDP neighborinformation is removed.
