The value of vRtrPimNgCRPGrpPrefixGrpMask indicates the mask which
is combined with the value of vRtrPimNgCRPGrpPrefixGrpAddr to get
the range of multicast group addresses for which the router
advertizes to be the Candidate RP. The value of vRtrPimNgAFGenCRPAddress
is sent as the RP address.