Architecture of an Integrated Router Interconnected Spectrally (IRIS)

The design of optical packet routers poses significant challenges both in terms of its architecture and component design. In this paper, we evaluate several alternatives for the architecture of such routers, and describe the architecture of IRIS (Integrated Router Interconnected Spectrally), an optical router being designed at Bell Laboratories. By combining load balancing with wavelength switching, the IRIS architecture can make use of thousands of wavelengths and provide terabits of capacity, well above the scalability limits of router architectures based on other approaches. The IRIS architecture uses load balancing to eliminate the need for centralized scheduling, and wavelength switching to allow N2 channels in an N x N space switch. We describe several architectural schemes for overcoming the limitations of the underlying optical devices in the design of IRIS. We also present two methods to improve the utilization of the optical buffers in IRIS to achieve high performance even with a small number of buffers.