Spatially and Spectrally Flexible Scheduling With Time-Slotted Lightpath-Switching

Abstract

Optical wavelength-routed networks enable parallel transmission of massive datasets on nonover-lapping wavelength channels. However, as the sizes of scientific workflows increase, the availability of multi-wavelength resources will fall short of supporting application needs. Rather, these resources must be allocated intelligently, efficiently, and flexibly to bear the burden of high-volume science. We propose lightpath-switching to support modification to the set of wavelength/route resources used to carry and transmit a lightpath signal intermittently throughout its lifetime. Lightpath-switching exposes the scheduler to flexible consumption of unused, fragmented resources during the request schedule but requires neither underlying network technology nor equipment enhancement. We explore the efficacy of lightpath-switching in terms of wavelength-switching, path-switching, and a combination of the two techniques. We prove these problems are NP-complete and develop optimization models and efficient heuristics to quantitatively and qualitatively evaluate the solution space against optimality benchmarks. Our evaluations consider cross-dimension resource consumption from the time, space, and spectrum domains, and our findings indicate great potential for increasing network-wide resource savings, particularly via wavelength-switching. Furthermore, evidence is presented to defend the claim that spectral flexibility has a greater impact on resource utilization efficiency than spatial flexibility.