End to End Scalable and Dynamically Reconfigurable Optical Architecture for Application-aware SDN Cloud Datacentres

Project Goals

The NEPHELE project is developing a dynamic optical network infrastructure that aims to overcome current architectural limitations and drastically reduce cost and power consumption, enabling cloud datacenters to scale gracefully.

Traditionally a data center has a fixed proportion of systems for computing and storage capacity and data transfer (principle of aggregation). The steady increase of cloud-based applications requires a huge increase in the underlying infrastructure of data centers, which necessitates an economically unacceptable non-linear expansion of the network components.

A continuous enlargement of data centers according to the traditional model is therefore more and more displaced by the concept of resource disaggregation, which is characterized by the establishment of a uniform cross-network and control layer. Here, the rigid structure of single servers is given up. The individual resource types interact software controlled in a data center-wide network. By thus achieved linear scaling the limits of network capacity and latency can be further raised, and thus significantly increases the efficiency of a data center.

On this, the resource disaggregation and Software Defined Networking project NEPHELE comes in. A higher-level control layer is to be developed with a northbound interface to the application layer and a southbound interface for hardware abstraction and dynamic network configuration. The research team relies on the enormous capacities of optical fibers and wants to exploit a combination of optical switches to achieve the ideal combination of large network bandwidth and cost reduction.

This is expected to result in an overall cost reduction of 30% and a reduction in energy consumption of 80%. This development will significantly strengthen NEPHELE’s European position in data center technology.

GWDG’s Role in the project

Being a member of NEPHELE, the GWDG’s role is the software development of the intra-DC SDN (Software-Defined Networking) controller containing the common SDN framework and the enhanced network services, which will then later be extended to enable VM migration between inter-DCs. A fully functional control plane overlay will be developed, including a SDN controller along with its southbound and northbound interfaces. The southbound interface abstracts physical layer infrastructure and allows dynamic hardware-level network reconfigurability. For this, the OpenFlow protocol, defined by Open Networking Foundation (ONF), has been selected as candidate for the southbound interface. The northbound interface links the SDN controller with the application requirements through an Application Programming Interface (API). There is not any specific standard already available for northbound interface, even if work is currently in progress in the Northbound Interfaces Working Group in ONF. However, we can recognize a common approach across the different SDN controllers, which are based on the adoption of the Representational State Transfer (REST) paradigm and the usage of HTTP messages at the north-bound interface. Furthermore, GWGD encourages NEPHELE’s innovative control plane that enables Application Defined Networking and merges hardware and software virtualization over the hybrid optical infrastructure. It also integrates SDN modules and functions for inter-datacenter connectivity.

Project Partners

NEPHELE is an European join project with partner from science and economy. One of the partners is from Israel.

National Technical University of Athens und University of Patras, Greece

Interoute S.p.A, Rom und Nextworks Srl, Pisa, Italy

Seagate Technology LLC, Dublin, Ireland

Mellanox Technologies, Israel

Project coordinator is the Institute of Communication & Computer Systems of the National Technical University of Athens.

Additional Information

NEPHELE Factsheet 03/2015

Video presentation of the project

project logo


Dr. Muzzamil Aziz
Amirreza Fazely Hamedani
Prof. Dr. Philipp Wieder



01.02.2015 - 31.01.2018



Funded by

Horizon2020 logo

Europäische Union, Horizon 2020, Förderkennzeichen: 645212.