城域以太网挑战SDHMetro Ethernet Challenges SDH罗忠生/LUO Zhong-sheng 王利存/WANG Li-cun 陈丹/CHEN Dan摘要：文章分析了城域网的需求以及SDH在城域网中所面临的问题，研究了城域网为什么要采用以太网技术，介绍了影响以太网运营的关键技术的进展，以城域以太网市场应用实例说明城域以太网将对SDH挑战，最后给出了SDH与以太网共存情况下的城域网演进策略与方案。关键词：城域网；以太网；同步数字体系Abstract:The market demand for MAN and the application problems of SDH in MAN are analyzed first and then the reason of using Ethernet technologies in MAN is studied. The advancement of key technologies for Ethernet operation is introduced. The market deployme
