Abstract
Traditional wired data center networks (DCNs) suffer from cabling complexity, lack flexibility, and are limited by the speed of digital switches. In this paper, we alternatively develop a top-down traffic grooming (TG) approach for design and provisioning of optical wireless DCNs. While switches are modeled as hybrid opto-electronic cross-connects, links are modeled as wavelength division multiplexing (WDM) capable free-space optic (FSO) channels. Using the standard TG terminology, we formulate the optimal mixed integer linear problem considering the virtual topology, flow conversation, connection topology, non-bifurcation, and capacity constraints. Thereafter, we develop a fast sub-optimal solution where mice flows (MFs) are groomed and forwarded on predetermined rack-to-rack (R2R) lightpaths. On the other hand, elephant flows (EFs) are forwarded over dedicated server-to-server (S2S) express lightpaths whose routes and capacity are dynamically determined based on wavelength and capacity availability. Emulation results show that proposed models and algorithms provide a significant throughput improvement upon traditional DCNs for both MFs and EFs.