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SDH传输是一种全新的传输网体制,其特点是使1.5Mbit/s和2Mbit/s两大数字体系(北美、日本、欧洲三个地区性标准)在STM-1等级上获得统一,第一次真正实现了数字传输体制上的世界性标准;因简化了交叉连接设备(DXC)的结构,上下业务十分容易,使网络易于容纳和引入各种新的宽带业务;大大增强了网络的运行管理和维护(OAM)能力;不同厂家的产品可以互通,降低了联网成本;相对于PDH而言,其网络可用性和误码性能均得到改善;SDH网与现有的PDH网可以完全兼容。毫无疑问,传输网的发展方向应该是高度灵活和规范化的SDH网,它必将最终取代PDH传输体制,为B-ISDN的
SDH transmission is a brand-new transmission network system, its characteristic is to make 1.5Mbit / s and 2Mbit / s two major digital systems (North America, Japan, Europe three regional standards) Uniform on the STM-1 level, the first Times to truly realize the global standard in the digital transmission system. Because of simplifying the structure of the cross-connect equipment (DXC), the uplink and downlink services are very easy to make the network easy to accommodate and introduce various new broadband services; the operation and management of the network is greatly enhanced And maintenance (OAM) capabilities. Products from different vendors can interoperate and reduce networking costs. Compared with PDH, network availability and error performance are improved. The SDH network is fully compatible with the existing PDH network. There is no doubt that the development of transport networks should be highly flexible and standardized SDH network, it will eventually replace the PDH transmission system for the B-ISDN