As the Internet application development, customer network application needs and to Internet access requirements are constantly improve, the traditional digital subscriber line ( DSL ) technology has failed to meet demand. 随着互联网应用的不断拓展,客户网络应用需求和对网络接入的要求也在不断提高,传统的DSL(数字用户线)技术由于受带宽和接入距离的限制,已无法满足需求。