HPE FlexNetwork HSR6800 series Configuration Manual page 44

Table 16 Action to take when no echo packet is received from a neighbor
No echo packet received from the
neighbor
In normal mode, no echo packet is received
when the Echo timer expires.
In enhanced mode, no echo packet is received
when the Echo timer expires.
Link auto-recovery mechanism
If the port shutdown mode upon detection of a unidirectional link is set to auto, DLDP automatically
sets the state of the port where a unidirectional link is detected to DLDP down. A DLDP down port
cannot forward data traffic or send/receive any PDUs except DLDPDUs.
On a DLDP down port, DLDP monitors the unidirectional link. Once DLDP finds out that the state of
the link has been restored to bidirectional, it brings up the port.
The DLDP down port sends out a RecoverProbe packet every2 seconds, which carries only
information about the local port. Upon receiving the RecoverProbe packet, the remote end returns a
RecoverEcho packet. Upon receiving the RecoverEcho packet, the local port checks whether
neighbor information in the RecoverEcho packet is the same as the local port information. If they are
the same, the link between the local port and the neighbor is considered to have been restored to a
bidirectional link, and the port will transit from Disable state to Active state and re-establish
relationship with the neighbor.
Only DLDP down ports can send and process Recover packets, including RecoverProbe packets
and RecoverEcho packets. If related ports are manually shut down with the shutdown command,
the auto-recovery mechanism will not take effect.
DLDP neighbor state
A DLDP neighbor can be in one of the three states described in
Table 17 DLDP neighbor states
DLDP neighbor
state
Unknown
Two way
Unidirectional
Action
DLDP sets the state of the neighbor to one way, and
determines the subsequent action to take depending on
the state of the other neighbors:
•
•
•
Description
A neighbor is in this state when it is just detected and is being probed. A neighbor is
in this state only when it is being probed. It transits to Two way state or
Unidirectional state after the probe operation finishes.
A neighbor is in this state after it receives response from its peer. This state
indicates the link is a two-way link.
A neighbor is in this state when the link connecting it is detected to be a
unidirectional link. After a device transits to this state, the corresponding neighbor
entries maintained on other devices are removed.
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If all the neighbors are in one way state, removes all
the neighbor entries, changes the DLDP port state to
Disable, outputs log and tracking information, and
sends Disable packets to the neighbors. In addition,
depending on the user-defined DLDP down mode,
shuts down the local port or prompts users to shut
down the port.
If the state of some neighbors is unknown, takes no
action until the state of these neighbors is
determined.
If a two-way neighbor is present, removes all the
one-way neighbors, but does not change the DLDP
port state.
Table 17.