1-5Timer DescriptionEntry aging timerWhen a new neighbor joins, a neighbor entry is created and thecorresponding entry aging timer is enabledWhen an advertisement packet is received from a neighbor, the neighborentry is updated and the corresponding entry aging timer is updatedIn the normal mode, if no packet is received from the neighbor when the entryaging timer expires, DLDP sends an advertisement packet with an RSY tag,and deletes the neighbor entry.In the enhanced mode, if no packet is received from the neighbor when theentry aging timer expires, DLDP enables the enhanced timerThe entry aging timer length is three times the advertisement timer length.Enhanced timerIn the enhanced mode, if no packet is received from the neighbor when theentry aging timer expires, DLDP enables the enhanced timer for theneighbor. The enhanced timer length is 10 secondsThe enhanced timer then sends one probe packet every second and eightpackets successively to the neighbor.If no echo packet is received from the neighbor when the enhanced timerexpires, the state of the local end is set to unidirectional communication stateand the state machine turns into the disable state. DLDP outputs log andtracking information and sends flush packets. Depending on the user-definedDLDP down mode, DLDP disables the local port automatically or promptsyou to disable the port manually. Meanwhile, DLDP deletes the neighborentry.DelayDown timerWhen a device in the active, advertisement, or probe DLDP state receives aport down message, it does not removes the corresponding neighborimmediately, neither does it changes to the inactive state. Instead, it changesto the delaydown state first.When a device changes to the delaydown state, the related DLDP neighborinformation remains, and the DelayDown timer is triggered. The DelayDowntimer is configurable and ranges from 1 to 5 seconds.A device in the delaydown state only responds to port up messages.A device in the delaydown state resumes its original DLDP state if it receivesa port up message before the delaydown timer expires. Otherwise, itremoves the DLDP neighbor information and changes to the inactive state.DLDP Operating ModeDLDP can operate in two modes: normal mode and enhanced mode.Table 1-4 DLDP operating mode and neighbor entry agingDLDPoperatingmodeDLDP detects whetherneighbors exist or notwhen neighbor tablesare agingThe entry aging timeris enabled or notduring neighbor entryagingThe enhanced timer is enabledor not when the entry agingtimer expiresNormalmode NoYes (The neighbor entryages out after the entryaging timer expires)NoEnhancedmode YesYes (The enhancedtimer is enabled afterthe entry aging timerexpires)Yes (When the enhanced timerexpires, the state of the local endis set to unidirectional link, andthe neighbor entry is aged out.)
