H3C Technologies H3C S10500 Series Switches - Manual (Page 42)

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DLDP timer Description
Echo timer
This timer is set to 10 seconds. It is triggered when a device transits to the Probe
state or when 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 does the following:
Sends Disable packets.
Either prompts the user to shut down the port or shuts down the port automatically
(depending on the DLDP down mode configured).
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 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 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 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 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.
If a device in the DelayDown state detects a port-up event before the DelayDown
timer expires, it resumes its original DLDP state. If not, when the DelayDown timer
expires, the device removes the corresponding DLDP neighbor information and
transits to the Inactive state.
RecoverProbe timer
This timer is set to 2 seconds. 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 normal or enhanced mode.
• 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.
• In enhanced DLDP mode, when an entry timer expires, the Enhanced timer is triggered and the
device tests the neighbor by sending up to eight Probe packets at the frequency of one packet per
second. If no Echo packet has been received from the neighbor when the Echo timer expires, the
device transits to the Disable state.
Table 12 shows the relationship between the DLDP modes and neighbor entry aging.