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Project Title


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. The project aims to develop a higher-level control layer with a northbound interface to the application layer and a s

The 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 Funding

European Union, Horizon 2020, Grant Agreement No: 645212

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





Dr. Muzzamil Aziz
Amirreza Fazely Hamedani
Dr. Philipp Wieder



01.02.2015 - 31.01.2018