产品级代码，可根据开机时间（微妙级）随机生成mac地址,从而避免同批次产品IP冲突。保证出厂产品具有不同的mac地址，而不用手动去逐个修改-Production code, mac address can be randomly generated according to the boot time (microsecond). Ensure that manufactured products have different mac address, without having to man