Multi-Granular Optical Path Networking Technologies

Optical path technologies exploit wavelength routing, enhance node throughput and reduce network cost. ROADMs have recently been introduced and a large scale deployment is being conducted in North America and Japan. GMPLS controlled OXCs have also been used to create nation-wide testbeds. New broadband services including IP TV and high definition TV are now imminent and further traffic expansion is expected in the near future. This will result in a significant increase in the number of wavelength paths that should be cross-connected at nodes, and hence optical node throughput must be enhanced. One important technology that can resolve this problem is the introduction of wavebands and Hierarchical Optical path cross-Connects (HOXCs). This paper explores recent advances in the research and development of hierarchical multi-layer photonic networks.