IFM_ETHER_SUBTYPE_SET
ifmr->ifm_active = IFM_ETHER_SUBTYPE_SET(IFM_1000_T);
ifmr->ifm_active = IFM_ETHER_SUBTYPE_SET(IFM_100_TX);
ifmr->ifm_active = IFM_ETHER_SUBTYPE_SET(IFM_10_T);