NEPHELE: An End-to-End Scalable and Dynamically Reconfigurable Optical Architecture for Application-Aware SDN Cloud Data Centers

The efficient integration of optical switching in data center networks is being studied as a means to cope with surging traffic demands. Optically switched, flatter network architectures more efficiently handle the east-west traffic profiles of modern data centers. Limitations in the port count and reconfiguration speed of optical switches require novel network designs offering network scalability and dynamicity. Interaction of the optically switched data plane with a software-defined control and orchestration framework, meeting current common practices in data centers, necessitates the design of custom network control algorithms and software modules as well as the integration of novel functionalities. The approach of the European project NEPHELE is presented, offering an endto- end solution that addresses the optical data plane, the control plane, and its interaction with the application layer.

Introduction

Data centers are the hubs of our content-centric Internet. The proliferation of fifth generation (5G) mobile and cloud applications, video distribution, and the emerging Internet of Things is bringing data center traffic on a steep growth reaching 25 percent annually [1]. This soaring traffic demand is outpacing progress in network infrastructure, which generally follows Moore's law [2], threatening a capacity crunch inside the data center. The largest portion of this traffic concerns communications between servers and storage inside the data center, exacerbating the challenge. Following an east-west traffic profile, intra-data-center communication is dwarfing north-south traffic from/to the Internet, thus putting more stress on legacy data center network architectures that are inherently more appropriate for north-south flows (i.e., fattree topologies).