The value of vRtrPimNgCRPGrpPrefixGrpAddr combined with the value of
vRtrPimNgCRPGrpPrefixGrpMask indicates 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.