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FIM Faculty Chairs Computer Networks and Communications Research Overview Areas


 Energy Efficiency

 

Contact

Person:

 
Prof. Dr. H. De Meer, Andreas Berl, Gergö Lovász, Florian Niedermeier

 
Research
Description:

We aim at the development of a comprehensive concept for energy efficiency, involving all layers. This involves physical nodes, cooling of nodes, networking hardware, communication protocols, and finally the services themselves that running on the nodes.
The key technology to achieve an energy efficient operation of the servers in data centers is virtualization. Virtualization and virtualization management concepts will be extended to support energy efficiency. Virtual machines that encapsulate virtualized services can be moved, copied, created and deleted depending on management decisions. Energy efficiency can be achieved by consolidating hardware and reducing redundancy. Unused servers can be turned off (or hybernated) to save energy. Not only the aspect of load is considered, also the “heat” of a service is measured and considered in the movement of it. When a node is excessively used or is near to other high loaded nodes, hotspots can appear. To avoid such hotspots, heat can be distributed across sites. Services can be moved from sites with high load or high temperature to sites with less load and lower temperature. This kind of an energy-efficient management of resources has to be realized by an autonomous energy management that is as transparent as possible to the user of a service.
Another element is the optimization of the network and its protocols. Some hardware already offers features that allows an energy-efficient operation of the network (e.g. turning of network interfaces, throttling of CPUs), and have to be exploited. Network protocols have to be optimized (or even to be redeveloped) in a way that they support the energy efficient operation of the network elements. A network device should be enabled to delegate services to other devices, if possible (clients are not aware of this delegation). Such a delegation would allow the transfer of a service from an energy inefficient to a rather energy efficient device or to a device which has to be always on anyway (e.g. a router). The delegating device can change to dormant mode or can be turned off. In a network many basic services have to be active to periodically confirm their availability even when no communication is taking place. These so called “soft states” make it impossible to turn off components of the hardware and of the operating system. New protocols could work around such soft states to increase the energy efficiency of the network.  Also signaling is a highly important subject in energy-efficient networks. Whereas the characteristics of data and signaling traffic highly differ, the same technology and mechanisms are used for both (in-band signaling). Signaling needs only low bandwidth but can occur anytime whereas data traffic occurs after signaling has taken place, requires usually high bandwidth and is passed over all layers up to the application layer. Therefore data and signaling traffic should not be processed in the same way. The possibilities of out-of-band signaling have to be analyzed.
To comprehensively raise the energy efficiency of a system, all of its layers have to be considered, including application layer services. Services have different needs concerning the environment they are running on or have special properties that support the energy efficiency of the underlying system (e.g. certain usage patterns). A service might only be used weekdays from 8h to 18h or have peak usage at a certain time of the day. A user might, e.g., consider a trade-off between a more energy efficient service and a more reliable one, and compose the service in a way, that it fits best. This way, it is also possible to develop accounting mechanisms that depend on the energy that has been used by a service.
Also the air-conditioning that is needed to cool servers in data centers causes about half of the overall energy costs of the data center. The challenge in cooling comes from an inefficient usage of the cooled air. The optimization of the air condition of a data center is a very complex subject and depends heavily on the data center facility.


Launched Projects:

      

  
Related Events:

  
Jürgen Heidegger, Director Marketing Infrastructure Products, Fujitsu Siemens Computers, München, Deutschland, Kolloquium: "Energieeffiziente Infrastrukturen für das Rechenzentrum - Ökonomie und Ökologie im sinnvollen Miteinander", 11.12.2007


Universität Passau, e-Energy Conference 2010

  




  

 IT-Security

 

Contact

Person:

 
Prof. Dr. H. De Meer, Ralph Herkenhöner, Harald Hauff, Muhammad Ali, Michael Niedermeier

 
Research
Description:

Overlay networks, most recently the peer-to-peer (P2P) paradigm, have added new services to networking. While overlay networks enhance communication efficiency and robustness of popular service applications, trust into all parties is assumed. Secure and fair operations have been neglected in many approaches. Our research aims to 1. strengthen cooperative behavior in P2P-based networks 2. enable secure and private, unobservable operations.

Integrity-based computing enforces data integrity in distributed systems, and therefore e.g. Trusted Platform Models can provide a fundament for secure cooperation. Peer-to-peer networks distribute their service at the price of additional attack possibilities. Malicious behavior can appear on various levels, from Denial-of-Service attacks utilizing community resources to unobservable misbehavior and undermining policies. The lack of peer-to-peer networks of monitoring, accounting, and enforcing security policies becomes a thread of future networks.

The emerging trend of network privacy strengthens data protection of individuals. Anonymity systems protect the relationship between identities and events, e.g. content requests, mails, other traces of network activity. Captured communication relationships can offend privacy of individuals. Research in this field must enhance the usability of solutions. Recent exposures showed that simple approaches of pseudonym data do fail and reveal sensible data of individuals.

Our research combines network privacy with mechanisms for secure cooperation. This is beneficial since unobservability is only reachable with a reasonable anonymity set, i.e. multiple cooperation parties.


Launched Projects:

  

  
Related Events:

  

  




 Virtualization

 

Contact

Person:

 
Prof. Dr. H. De Meer, Andreas Berl, Andreas Fischer, Gergö Lovàsz, Florian Niedermeier

 
Research
Description:

 

The management of virtualized resources is a main research field of our research group. Resources are virtualized in various different contexts:

 

In data centers, e.g., server hardware is virtualized by using system virtualization methods. This virtualization enables the creation of virtual machines that can be used similar to physical servers. Virtual machines can be created, destroyed, copied or moved from server to server. Furthermore, more than a single virtual machine can be hosted by a physical server. This is used to achieve a consolidation of virtual machines on a small number of physical servers, which saves hardware and energy. This kind of virtualization and consolidation can also be extended to office environments and home environments.

 

Another field that virtualizes resources is, e.g., network virtualization. Services, routers, and links are virtualized in order to form virtual networks with highly interesting properties. These networks are a possible approach towards a Future Generation Internet and provide important features like quality-of-service, high availability of services, or resilience against disasters. Virtualization can also be applied to Future Home Environments, to enable a fair sharing of resources among users while reducing energy consumption.

 

All these (and other) applications of virtualization require a management of virtual resources which is highly dynamic, mostly autonomic and often based on a decentralized approach.

 

Peer-to-Peer (P2P) and Overlay networks, which are a special variation of network virtualization, are also a research field of our research group. This involves the analysis of different P2P paradigms and their traffic patterns (signaling traffic and data traffic), cross-layer optimization, and mobility in P2P-overlays (Mobile P2P). 


Launched Projects:

  

  
Related Events:

  

  




 

 Selforganization

 

Contact

Person:

 
Prof. Dr. H. De Meer, Richard Holzer, Patrick Wüchner

 
Research
Description:

  
There are many different kinds of self-organizing systems in the world. They can be of technical nature (e.g. computer networks), biological nature (e.g. colony of ants), physical nature (e.g. force of elementary magnets) or of other kind. The main properties of self-organizing systems are emergence, adaptivity, decentralization and autonomy. A challange for the research in this field is the modelling of self-organizing systems with mathematical methods.


Launched Projects:

  

 

Related Events:

  

  




 Performance Modeling

 

Contact

Person:

 
Prof. Dr. H. De Meer, Patrick Wüchner

 
Research
Description:

 
Performance is one of the most important non-functional properties of computer and communication networks. The first step towards the control and optimization of performance is the ability to evaluate the performance.

One of the most common ways to evaluate the performance is to measure it. However, direct measurements at real systems are only possible if the system is already available. Additionally, doing optimizations based on measurements often involves costly trial-and-error cycles.

Therefore, our evaluations are based on formal mathematical models of the real system instead. Here, we mainly focus on analytic closed-form solutions, iterative numerical methods, and discrete-event simulation techniques for models based on stochastic processes, like Markov chains, as well as high-level model description methods, like queueing networks and stochastic Petri nets.

Especially for complex and self-organizing systems, we also employ models based on differential equations well-known in Physics and Biology research.


Launched Projects:

 
MOSEL-2 - Performance Modeling Language and Evaluation Environment

 

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 Last changed: 07.03.13