The number of changes to active RP mappings on this device.
Information about active RP mappings is available in
hwPimGroupMappingTable. Only changes to active mappings cause
this counter to be incremented. That is, changes that
modify the hwPimGroupMappingEntry with the highest precedence
for a group (lowest value of hwPimGroupMappingPrecedence).
Such changes may result from manual configuration of this
device, or from automatic RP mapping discovery methods
including the PIM Bootstrap Router (BSR) mechanism.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, for example
when the device is rebooted.