Low-Emissions Routing for Cloud Computing in IP-over-WDM Networks with Data Centers

Cloud Computing (CC) services are rapidly catching on as an alternative to conventional office-based computing. As cloud computing adoption increases, the energy consumption of the network and of the computing resources that underpin the cloud is growing and causing the emission of enormous quantities of CO₂. Research is now focusing on novel "low-carbon" cloud-computing solutions. Renewable energy sources are emerging as a promising solution both to achieve drastic reduction in CO₂ emissions and to cope with the growing power requirements of data centers. These infrastructures can be located near renewable energy plants and data can be effectively transferred to these locations via reconfigurable optical networks, based on the principle that data can be moved more efficiently than electricity. This paper focuses on how to dynamically route on-demand optical circuits that are established to transfer energy-intensive data processing towards data centers powered with renewable energy. Our main contribution consists in devising two routing algorithms for connections supporting CC services, aimed at minimizing the CO₂ emissions of data centers by following the current availability of renewable energies (e.g., coming from sun and wind). The trade-off with energy consumption for the transport equipments is considered. We also compare three different IP-over-WDM network architectures. The results show that relevant reductions, up to about 30% in CO₂ emissions can be achieved using our approaches compared to baseline shortest-path-based routing strategies, paying off only a marginal increase in terms of network blocking probability.