述SDH的优缺点？
述SDH的优缺点？
相关考题：
与PDH相比较,SDH的主要特点包含:SDH有一套标准的信息等级结构、SDH的帧结构是矩形块状结构、SDH帧结构中拥有丰富的开销比特、( )。 A. SDH有矩形信息等级结构B.SDH有标准的帧结构C.SDH拥丰富的信息结构D.SDH具有统一的网络节点接口
On an ONS 15454 node you can tunnel a（n） （）.A、 SDH circuit over a SONET network delivering it as an SDH signalB、 SDH circuit over a SONET network delivering it as a SONET signalC、 SONET circuit over an SDH network delivering it as an SDH signalD、 SONET circuit over an SDH network delivering it as a SONET signal
On an ONS 15454 node you can tunnel an （）.A、SDH circuit over a SONET network delivering it as an SDH signalB、SDH circuit over a SONET network delivering it as a SONET signalC、SONET circuit over an SDH network delivering it as an SDH signalD、SONET circuit over an SDH network delivering it as a SONET signal
单选题On an ONS 15454 node you can tunnel a（n） （）.A SDH circuit over a SONET network delivering it as an SDH signalB SDH circuit over a SONET network delivering it as a SONET signalC SONET circuit over an SDH network delivering it as an SDH signalD SONET circuit over an SDH network delivering it as a SONET signal
问答题SDH与PDH比较有哪些优缺点？