Energy efficiency benefits of introducing optical switching in Data Center Networks

In this paper we analyze the impact of WDM-enhanced optical circuit switching on the power consumption of multiple Data Center Network (DCN) architectures. Traditional three-tier Tree, Fat-Tree and a ring-based structure are evaluated and optical switching is selectively introduced on different layers of the network topology. The analysis is based on network-level simulations using a transport network planning tool applied to small-scale setups of the considered DCNs. The obtained results show that introducing all-optical switching within the DCN leads to reduced power consumption in all architectures, except the traditional Tree. This is caused by the inability to perform efficient traffic grooming and smaller average nodal degree of this architecture. Enabling optical switching only at the aggregation layer results in the highest energy savings in Fat-Tree and traditional Tree, while an optically switched core benefits most the ring-based network. For the latter, the core ring nodes need fewer long-reach transponders at the trunk interfaces and benefit from more efficient traffic grooming in the access part.