fib_get_nhop_idx
uint32_t fib_get_nhop_idx(struct fib_data *fd, struct nhop_object *nh);
fhp->nexthop = fib_get_nhop_idx(da->fd, rnd.rnd_nhop);
nh = fib_get_nhop_idx(da->fd, rt_get_raw_nhop(rt));