This notification signifies that the SNMP entity, acting as an
agent, has detected that one of its NHRP entities, acting as an
NHRC, has successfully registered with an NHRS to which it was 
not already registered.

This notification signifies that the SNMP entity, acting as an
agent, has detected that that one of its NHRP entities, acting 
as a NHRC, has detected(by repeated registration retries or 
learnt from some other source(e.g. from a lower layer protocol))
that the NHRS it was registered to, or was trying to register 
to, is operationally down(from the NHRC's perspective).
This notification doesn't indicate that the concerned NHRP 
server is down or unreachable or not even that it is unable to
provide (other)NHRP services. It just indicates that the NHRC 
couldn't register successfully with the NHRS.
This notification will be be sent only once for a down  event 
i.e. two consecutive cneNotifNextHopRegServerDown notifications
(for the same NHRS) must always be interspersed by a 
cneNotifNextHopRegServerUp notification(for the same NHRS).

This notification signifies that the SNMP entity, acting as an
agent, has detected that one of its NHRP entities, acting as an
NHRS perceives that an NHRP entity(an NHRC), which was not 
already registered, has just now successfully registered.

This notification signifies that the SNMP entity, acting as an
agent, has detected that one of its NHRP entities, acting as an
NHRS perceives that an NHRP entity, acting as an NHRC, is no 
more registered or failed to register.
This notification will be be sent only once for a down event 
i.e. two consecutive cneNotifNextHopRegClientDown notifications
(for the same NHRC) must always be interspersed by a 
cneNotifNextHopRegclientUp notification(for the same NHRC).

This notification signifies that the SNMP entity, acting as an
agent, has detected that one of its NHRP entities perceives that
it has learnt the protocol-to-NBMA address binding information
for an NBMA next hop(which it didn't have). An NHRP entity might
learn the same address binding information for a next hop peer
as part of multiple address resolutions; this notification 
should be sent only when it first learns this address binding
information.

This notification signifies that the SNMP entity, acting as an
agent, has detected that one of its NHRP entities perceives that
it has lost the protocol-to-NBMA address binding information for
an NBMA next hop(which it earlier had).
An NHRP entity might maintain multiple cache entries, with the 
same address binding information, for the same next hop peer
(corresponding to different destinations reachable via this next
hop peer); This notification will be be sent only when the 
address binding information is lost meaning only when all such 
entries are deleted.
This notification will be be sent only once for a 'down' event 
i.e. two consecutive cneNotifNextHopPeerDown notifications
(for the same NHP) must always be interspersed by a
cneNotifNextHopUp notification(for the same NHP).

This notification signifies that the
SNMP entity, acting in an agent role, has detected that one of
its NHRP entities(identified by the ifIndex) has been very
frequently reaching the threshold on the rate of NHRP protocol
messages exchanged in an NBMA network. It is left to each
individual implementation to determine the threshold frequency
of this event(threshold being reached on the rate of NHRP
protocol messages exchanged) which should result in a
notification.
The ifIndex object in this notification represents the use of a
generic ifIndex which reflects a specific NBMA subnetwork
related interface as determined by an implementation.