(1) SDH transmission system in the world to have a unified standard for digital transmission rate of the frame structure and standard optical interface, allowing network management system interoperability, and therefore has good lateral compatibility, is fully compatible with existing PDH, and accommodate variety of new traffic signals, the formation of a unified global standard digital transmission system, improve the reliability of the network.

(2) Different levels of code access system SDH frame structure arranged stream payload area very regular, and the payload is synchronized with the network, it can use the software the first direct high-speed signal drop low-speed tributary signal, a multiplexing features, to overcome the PDH plesiochronous multiplexing scheme for all the high-speed signal multiplexing gradually break down and regeneration process, due to the greatly simplified the DXC, reducing the back-interface multiplexing equipment, improve the network of business transfer transparency.

(3) As a result of the more advanced add-drop multiplexer (ADM), Digital Cross Connect (DXC), self-healing network capabilities and reassembly function it is very powerful, with a strong survival. SDH frame structure due to a 5 percent overhead bits arranged signal, it is especially powerful network management functions, and can form a unified network management system for the automation of the network, intelligent, channel utilization and lower network costs and vascular viability played a positive role.

(4) Since the SDH network topology structure, consisting of a network it is very flexible, it can enhance network monitoring, operation management, and auto-configuration feature, optimize network performance, but also to network operation flexible, safe and reliable, the network The very complete and diverse.

(5) SDH freedom combination thereof can block transmission and switching performance of its Series device to achieve different levels and a variety of network topologies, very flexible.

(6) SDH does not belong to some kind of transmission medium, which can be used for twisted pair, coaxial cable, but for the transmission of SDH fiber high data rate is required. This feature shows that, SDH trunk channel suitable not only for, but also for regional channels. For example, China's national and provincial trunk cable network is using SDH, and it's also easy to mix compatible with fiber-optic cable network (HFC).

(7) From the point of view of the OSI model perspective, SDH belong to their lowest level of the physical layer and does not have strict restrictions on their level, easy to use on a variety of network technologies SDH, ATM or IP transport support.

(8) SDH is strictly synchronized, thus ensuring the whole network is stable and reliable, less errors, and facilitates reuse and adjustments.

(9) open standard optical interface can be implemented on a basic cable transversely compatible segment, reducing networking costs.