ncm_header16
struct ncm_header16 *hdr;
hdr = (struct ncm_header16 *)sc->sc_tx_buf;
struct ncm_header16 *hdr16;
hdr16 = (struct ncm_header16 *)buf;
if_setifheaderlen(ifp, sizeof (struct ncm_header16) +
(sizeof(struct ncm_header16) + sizeof(struct ncm_pointer16))