Ideal as a new generation of SDH transmission system with automatic route selection capability, upper and lower circuit convenient, maintenance, control, management is strong, the standard uniform, easy to transfer a higher rate of business, etc., can be well adapted to the rapid development of communications network It needs. So far, SDH has been an unprecedented application and development. In standardization, and has established a series of recommendations to be established has been basically covering all aspects of SDH. In the trunk network and long-distance networks, relay networks, access networks have been widely applied in it. And in optical fiber communications, microwave communications, satellite communications are also actively engaged in research and application.

In recent years, video on demand, multimedia services and other broadband services have sprung up have emerged to SDH applications provide a broad space in the access network. SDH technology in the access network benefits are: 1) the high demand for reliable, high-quality business of large enterprises and users, SDH provides ideal network performance and service reliability. 2) can be extended to the client network, simplifying maintenance. 3) the use of SDH inherent flexibility enables network operators faster and more efficiently provide the required long-term and short-term business needs.

From the technical point of view, the relative bandwidth requirements of the access layer is smaller, the need to provide an integrated service delivery Ethernet, TDM, ATM and so there may be. In SDH systems-based and can provide Ethernet, ATM transport and process systems (including TDM, Ethernet and ATM interfaces, even including Ethernet and ATM switching modules) will be the main method of transmission access layer solution, this approach can be inexpensively Providing high quality leased line, ATM, Ethernet and other services on a service provider point (POP) access, transfer and protection.

With the backbone transmission capacity is increasing, the access capacity metro transport network are also diverse. But IP-based network business is still unpredictable, which requires transmission network with better adaptability, and this adaptability is not just a network interface or network capacity, adaptability, and requires a network connection from adaptability. In general, low-cost, flexible and rapid completion carrier end office access to business and service convergence client is a major demand of the future metro access system.

Simply put, this SDH transmission using Ethernet and other business way is to different network-level business mapping by VC cascade to each slot SDH circuits, providing completely transparent transmission channel by the SDH network From the perspective of the physical layer device point of view is an integrated whole. This solution can greatly reduce the scale of investment, reduce equipment footprint, lower power consumption, thereby reducing the operating costs of the network operator. At the same time, the ability to provide multiple services also enables network operators to rapidly deploy network services, increase revenue, and enhance market competitiveness.

In summary, SDH its obvious superiority transmission network has become the mainstream of development. SDH technology and some advanced technology, such as optical wavelength division multiplexing (WDM), ATM technology, Internet technology (Packet over SDH), so that the role of SDH network is growing. SDH has been included in various countries in the 21st century high-speed communications network application project is the development direction of the telecommunications industry recognized digital transmission network, with great commercial prospects.