Today, the use of SONET and WDM multiply. Indeed, coupled use of these two technologies yields networks Optical integrating the strengths of SDH: transmission reliability and management bandwidth. These networks are currently expanding throughout the world and examples are more numerous

However, researchers are trying to reduce the stack
protocols used to arrive in all-optical solutions. Could
then see soon arrive networks constructed as follows:

Researchers are also set for challenge to achieve the "Optical
buffer "or other words to store the light ...