details are not provided for features introduced before release 21.2.
Path management mechanism through
Heartbeat messages between the Mobile Router (MR) and Network Mobility-Local
Mobility Anchor (NEMO-LMA) is important to know the availability of the peers,
to detect failures, quickly inform peers if recovery from the node fails and
allow a peer to take appropriate action.
How It Works
The MR and the LMA exchange
Heartbeat messages at regular intervals to detect the status of availability
between them. The NEMO-LMA initiates a Heartbeat exchange with the MR, by
sending a Heartbeat Request message, to check if the MR is reachable. The
NEMO-LMA records the sequence number of the last Heartbeat Request message and
is used to match the corresponding Heartbeat Response. The NEMO-LMA responds to
a Heartbeat Request message with a Heartbeat Response message, irrespective of
whether there is PMIPv6 session with the corresponding peer.
When the Binding Error message, with status set to 2, is received in
response to a Heartbeat Request message, the NEMO-LMA does not use Heartbeat
messages further with the corresponding peer.
When the LMA node does not receive the Heartbeat response for the
max-heartbeat-retransmission<value>exceed-action drop-session, the NEMO-LMA concludes
that the peer is not reachable. As such, the Heartbeat request to the peer is
stopped and clears the NEMO-LMA session without any traps.
If the restart counter value is different from the previous received
value, then it assumes that the peer had crashed and recovered. And so, the
existing NEMO-LMA sessions are cleared.