4-4
DLDP timer
Description
Echo timer
This timer is set to 10 seconds and is triggered when a device transits to the
Probe state or an enhanced detect is launched. When the Echo timer expires and
no Echo packet has been received from a neighbor device, the state of the link is
set to unidirectional and the device transits to the Disable state. In this case, the
device sends Disable packets, prompts the user to shut down the port or shuts
down the port automatically (depending on the DLDP down mode configured),
and removes the corresponding neighbor entries.
Entry timer
When a new neighbor joins, a neighbor entry is created and the corresponding
entry timer is triggered. When a DLDP packet is received, the device updates the
corresponding neighbor entry and the entry timer.
In the normal mode, if no packet is received from a neighbor when the
corresponding entry timer expires, DLDP sends advertisement packets with RSY
tags and removes the neighbor entry.
In the enhanced mode, if no packet is received from a neighbor when the Entry
timer expires, DLDP triggers the enhanced timer.
The setting of an Entry timer is three times that of the Advertisement timer.
Enhanced timer
In the enhanced mode, this timer is triggered if no packet is received from a
neighbor when the entry timer expires. Enhanced timer is set to 1 second.
After the Enhanced timer is triggered, the device sends up to eight probe packets
to the neighbor at a frequency of one packet per second.
DelayDown timer
A device in the Active, Advertisement, or Probe DLDP link state transits to
DelayDown state rather than removes the corresponding neighbor entry and
transits to the Inactive state when it detects a port-down event.
When a device transits to this state, the DelayDown timer is triggered. A device in
DelayDown state only responds to port-up events.
A device in the DelayDown state resumes its original DLDP state if it detects a
port-up event before the DelayDown timer expires. Otherwise, it removes the
corresponding DLDP neighbor information and transits to the Inactive state.
RecoverProbe timer
This timer is set to 2 seconds. In other words, a port in the Disable state sends
one RecoverProbe packet every two seconds to detect whether a unidirectional
link has restored.
DLDP mode
DLDP can operate in two modes: normal mode and enhanced mode, as described below.
z
In normal DLDP mode, when an entry timer expires, the device removes the corresponding
neighbor entry and sends an Advertisement packet with the RSY tag.
z
In enhanced DLDP mode, when an entry timer expires, the Enhanced timer is triggered and the
device sends up to eight Probe packets at the frequency of one packet per second to test the
