There are five basic purposes about realizing optical transmission network: to realize super-capacity optical network; to achieve the scalability of the network; to realize network reconfiguration, to achieve the purpose of flexible reorganizing network; to achieve network transparency; to allow interconnection of signals from any system and different formats; to achieve fast network recovery and the recovery time could be up to 100ms, which will have no influence on the majority of business. In order to further realize optical layer monitoring and enhance optical layer performance, ITU-T is investigating the problem of additional optical overhead and digital wrappers in the optical layer.   

The solution to solve the bottleneck problem of the whole network - optical access network

Over the past few years, the core of the network has changed dramatically, with generations of changes in both switching and transmission. Sooner or later, this part of the network will become a fully digital, software-dominated and controlled, highly integrated and intelligent network. On the other hand, the existing access network is still a primitive analog system dominated (over 90%) by twisted pair copper wires. The great contrast between the two technologies indicates that access network has become a bottleneck restricting the further development of the whole network.The only long-term solution to this bottleneck is the optical access network. 

The main purpose of using optical access network in access network is to reduce maintenance & management cost and failure rate, to develop new equipment and increase new revenue, to cooperate with the adjustment of local network structure to reduce nodes and expand coverage, to take full advantage of the benefits of optical fiber, to build a transparent optical network to meet the multimedia era.

The development status and trend of several aspects of optical fiber communication will determine the future pattern of telecommunication network and information industry to a great extent and also have a huge impact on socio-economic development in the next century.