IFBIF_ROOT
if ((bif->bif_flags & IFBIF_ROOT) == 0) {
bif->bif_flags &= ~(IFBIF_DESIGNATED | IFBIF_ROOT);
root_port->bif_flags |= IFBIF_DESIGNATED | IFBIF_ROOT;
#define IFBIF_KEEPMASK (IFBIF_SPAN | IFBIF_DESIGNATED | IFBIF_ROOT)