The IP address which when combined with the corresponding
value of hwPimSGRpfRoutePrefixLength identifies the route used
to find the RPF interface towards the source. The
InetAddressType is given by the hwPimSGRpfNextHopType object.
This address object is only significant up to
hwPimSGRpfRoutePrefixLength bits. The remainder of the
address bits are zero.