SDH (Synchronous Digital Hierarchy) network is composed of terminal MUX, divarication MUX, REG and SDXC units etc, and they are used in transmission, multiplexing, divarication and cross-connecting of synchro information.

• 同步数字体系(SDH)网络由终端复用器、分插复用器、再生中继器和同步数字交叉连接设备网络单元组成,进行同步信息传输、复用、分插和交叉连接。