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Software-defined Environments

Software-defined environments promise to increase the flexibility and efficiency of networking, computing, and storage infrastructures. The conceptual and technical cornerstones of software-defined environments are:

  • Logically centralized control: based on a holistic global view onto networking, compute, and storage resources, these resources can be managed more easily and efficiently. Note that although control is logically centralized, it might still be physically distributed to increase scalability and availability.

  • Virtualization: Based on virtualization technologies, functionality becomes independent of dedicated physical hardware, and can be distributed flexibly to utilize and share available physical resources efficiently.

  • Open standard interfaces to hardware: open standard interfaces to hardware enable the logically centralized controller to control hardware resources. Moreover, exposing functionality through standard interfaces allows for adapting and utilizing available hardware resources that previously appeared to be “black boxes”.

In our research, we develop concepts to improve the performance, efficiency, consistency, and fault-tolerance of distributed software-defined environments.


Software-Defined Networking

The trend towards software-defined environments started with the advent of software-defined networks (SDN). SDN separates the network control plane, which is responsible for controlling the network elements (switches), from the data plane, which is responsible for forwarding packets. Network control is outsourced from switches to a network controller, whose logic can be easily adapted by exchanging software components implementing the control logic.

In our research, we investigate how to utilize SDN to improve the performance of communication middleware systems (e.g., publish/subscribe systems) and networked applications (e.g., networked control systems as used, for instance, in automation). These systems were previously implemented on the application layer of the OSI model. With the availability of SDN, functionality can be pushed into the network to tailor the network to the application requirements to substantially improve performance like latency and throughput. Moreover, network and application can be optimized together as an holistic system.  

Moreover, we investigate concepts to physically distribute the SDN control plane to increase its  performance and availability, as well as concepts to ensure the consistency of the (distributed) SDN control plane and data plane.

Time-sensitive Networking

Time-sensitive Networks (TSN) consider network delay as the primary quality of service metric of communication targeting, for instance, applications from industrial automation, telerobotics, the smart grid, etc. In our research on TSN, we investigate how to optimally manage network resources under given delay constraints for both local area networks according to the IEEE 802 TSN standards, as well as wide-area IP networks, both originally not providing sufficient quality of service guarantees for time-sensitive applications.  

For IEEE 802 networks, we investigate, how to achieve deterministic bounds on network delay through the logically centralized configuration of scheduling complementing the IEEE 802.1Qbv standard for scheduled (time-triggered) traffic.

For wide-area networks, we investigate novel network abstractions and SDN-based resource management mechanisms for cyber-physical systems implementing a networked control system of geo-distributed sensor, actuators, and controllers.


Virtualization is an essential part of software-defined environments to become independent of dedicated hardware and utilize physical resources efficiently. However, if applications and services with stringent quality of service demands are executed on shared hardware, we face the problem of managing available resources such that quality of service guarantees are always fulfilled. To this end, we investigate suitable resource management concepts for virtualized systems, in particular, targeting time-sensitive systems and distributed systems with strict availability requirements such as cloud services.