A ciscoIetfPimExtInterfaceUp notification signifies the
restoration of a PIM interface. This notification
should be generated whenever cPimIfStatus
transitions into the 'active' state.
cPimIfStatus identifies the interface which 
was involved in the generation of this notification.

A ciscoIetfPimExtInterfaceDown notification signifies the
loss of a PIM interface. This notification should be
generated whenever an entry is about to be deleted from
the
cPimIfTable.
cPimIfStatus identifies the interface which 
was involved in the generation of this notification.

A ciscoIetfPimExtRPMappingChange notification signifies a
change in the RP Mapping on the device in question. A
change in RP Mapping could be because of addition of new
entries to the RP Mapping cache, deletion of existing
entries, or a modification to an existing mapping. The
type of change is indicated by cpimRPMappingChangeType.
cpimExtRPSetHoldTime is used to identify the row in the
cpimExtRPSetTable that is responsible for the generation
of this notification.
          
In case of modification to existing entries, a
notification should be generated once before the
modification (with cpimRPMappingChangeType set to
'modifiedOldMapping') and once after modification (with 
cpimRPMappingChangeType set to 'modifiedNewMapping').
          
NOTE: A high frequency of RP Mapping change could result
in a large number of ciscoIetfPimExtRPMappingChange
notifications being generated. Hence, in environments
where the possibility of a high frequency of RP Mapping
change exists, enable this notification with utmost care.