同步操作是SONET／SDH网络 极为重要的部份,这从其“同步光网” (Synchronous Optical Network)的 名称即可看出。同步操作可透过多任 务方式有效率地将低速语音、数据和 视讯流量加入高速讯号。它还能简化 DSO和DS1等低速率讯号的塞入和 取出过程,不需执行讯号解调就能将 它们并入千兆位等级讯号。这些优点 大幅降低SONET／SDH设备的成本 和设计复杂性,却也为SONET网络 的频率功能带来更大负担。SONET 频率功能除须确保网络所有设备同 步操作外,还要提供设备内部的频率 分布与频率管理。由于频率功能极为 重要,线路卡频率架构必须采用冗 余式设计,把主要系统频率故障导 Synchronous operation is an extremely important part of SONET / SDH networks, as can be seen from the name of its Synchronous Optical Network. Synchronization efficiently joins low-speed voice, data and video traffic to high-speed signals through multitasking. It also simplifies the insertion and removal of low-rate signals such as DSOs and DS1s and enables them to be incorporated into gigabit-level signals without the need for signal demodulation. These benefits dramatically reduce the cost and design complexity of SONET / SDH devices, but they also place a greater burden on the SONET network’s frequency capabilities. SONET frequency function in addition to ensuring that all network equipment synchronous operation, but also to provide internal frequency distribution and frequency management equipment. As the frequency function is extremely important, the line card frequency architecture must be redundant design, the main system frequency fault guide