1-3
Status Description
Probe DHCP sends packets to check if it is a unidirectional link. It enables
the probe sending timer and an echo waiting timer for each target
neighbor.
Disable DLDP detects a unidirectional link, or finds (in enhanced mode) that
a neighbor disappears. In this case, DLDP does not receive or send
DLDP packets.
Delaydown
When a device in the active, advertisement, or probe DLDP state
receives a port down message, it does not removes the
corresponding neighbor immediately, neither does it changes to the
inactive state. Instead, it changes to the delaydown state first.
When a device changes to the delaydown state, the related DLDP
neighbor information remains, and the Delaydown timer is triggered.
DLDP works with the following timers:
Table 1-2 DLDP timers
Timer Description
Advertisement sending timer Interval of sending advertisement packets, which can be
configured with a command line.
By default, the interval is 5 seconds.
Probe sending timer The interval is 0.5 second. In probe status, DLDP sends two probe
packets every second.
Echo waiting timer
It is enabled when DLDP enters probe status. The timeout time is
10 seconds.
If no echo packet is received from the neighbor when the Echo
waiting timer expires, the local end is set to unidirectional
communication status and the state machine turns into disable
status. DLDP outputs log and tracking information, sends flush
packets. Depending on the user-defined DLDP down mode,
DLDP disables the local port automatically or prompt the user to
disable the port manually. At the same time, DLDP deletes the
neighbor entry.
Entry aging timer
When a new neighbor joins, a neighbor entry is created, and the
corresponding entry aging timer is enabled.
When an advertisement packet is received from a neighbor, the
neighbor entry is updated, and the corresponding entry aging
timer is updated.
In normal mode, if no packet is received from the neighbor when
the entry aging timer expires, DLDP sends an advertisement
packet with RSY tag, and deletes the neighbor entry.
In enhanced mode, if no packet is received from the neighbor
when the entry aging timer expires, DLDP enables the enhanced
timer.
The interval set for the entry aging timer is three times of that for
the advertisement timer.