3Com 4800G Series, Configuration Manual

Page: 186 / 1246

186 C
HAPTER
22: DLDP C
ONFIGURATION
DLDP mode
DLDP can operate in two modes: normal mode and enhanced mode, as described
below.
■
In normal DLDP mode, when an entry timer expires, the device removes the
corresponding neighbor entry and sends an Advertisement packet with RSY
tag.
■
In enhanced DLDP mode, when an entry timer expires, the Enhanced timer is
triggered and the device sends up to eight Probe packets at a frequency of one
packet per second to test the neighbor. If no Echo packet is received from the
neighbor when the Echo timer expires, the device transits to the Disable state.
Entry timer When a new neighbor joins, a neighbor entry is created and the
corresponding entry timer is triggered. And when a DLDP packet is
received, the device updates the corresponding neighbor entry and the
entry aging timer.
In the normal mode, if no packet is received from a neighbor when the
corresponding entry aging 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 aging timer expires. Enhanced timer is
set to 10 seconds.
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.
If no Echo packet is received from the neighbor when the Echo timer
expires, the link is set as a unidirectional link 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.
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.
The setting of the timer ranges from 1 to 5 (in seconds). 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 Determines the interval to RecoverProbe packets, which are used to
detect whether a unidirectional link is restored. This timer is set to 2
seconds.
Table 31 DLDP timers
DLDP timer Description