Energy consumption and traffic scaling of dynamic optical path networks

Abstract

Dynamic path switching in lower layers such as optical or sub-wavelength layer-1 path connections is essential for future networks to provide end-to-end, bandwidth-guaranteed, large-capacity services without energy crunch. While this is almost generally agreed, the number of ports in optical switches tends to be limited by technological difficulties, severely restraining the scale of the network. However, video-related services, that occupies most of the traffic nowadays, could significantly alleviate such restraints if we utilized the nature of video usage. In most cases, video-related services are virtually provided through prior reservation scheme in which a relatively high call-blocking probabilities or long latency for a connection can be tolerated. This situation allows us to accommodate a relatively high number of subscribers with a limited number of switch ports. This paper shows that a network using optical switches with a technologically feasible number of ports, multi-granular paths, and a hierarchical network topology can be of a national scale accommodating several tens of millions of subscribers. The purpose of detailing a plausible network topology is to show that such a network offers a benefit of energy efficiency approximately three orders of magnitude compared with that extrapolated from recent router-based networks. We then discuss important technical aspects of such dynamic optical path networks including our several research activities. We emphasize the importance of vertically integrated research activities from application to device layers to develop the dynamic optical path networks.