Andreas Berl

Energy-Efficient Cloud Computing

Energy efficiency is increasingly important for future information and communication technologies (ICT), because the increased usage of ICT, together with increasing energy costs and the need to reduce green house gas emissions call for energy-efficient technologies that decrease the overall energy consumption of computation, storage and communications. Cloud computing has recently received considerable attention, as a promising approach for delivering ICT services by improving the utilization of data centre resources. In principle, cloud computing can be an inherently energy-efficient technology for ICT provided that its potential for significant energy savings that have so far focused on hardware aspects, can be fully explored with respect to system operation and networking aspects. Thus this paper, in the context of cloud computing, reviews the usage of methods and technologies currently used for energy-efficient operation of computer hardware and network infrastructure. After surveying some of the current best practice and relevant literature in this area, this paper identifies some of the remaining key research challenges that arise when such energy-saving techniques are extended for use in cloud computing environments.

Using System Virtualization to Create Virtualized Networks

The method of system virtualization is very popular for the use in data centers and desktop virtualization today. In this work, system virtualization is applied to core network elements (routers and links) in order to create a virtualized network. The selection of this virtualization method crucially determines the emerging network model. The network model consists of virtual networks, virtual routers, and virtual links that form overlays on top of the physical network. The properties, features, and limitations of this network model are analyzed and described in this paper. Additionally, a proof of concept implementation using currently available technology and infrastructure is presented. Finally the dynamic configurability of virtual resources in such a system virtualization based virtualized network is evaluated.

Self-organising Management Overlays for Future Internet Services

Networks are becoming service-aware implying that all relevant business goals pertaining to a service are fulfilled, and also the network resources are used optimally. Future Internet Networks (FIN) have time varying topology (e.g. such networks are envisaged in Autonomic Internet [1], FIND program [2], GENI program [3], FIRE program [4], Ambient Networks [5], Ad-hoc networks [6]) and service availability and service context change as nodes join and leave the networks. In this paper we propose and evaluate a new self-organising service management system that manages such changes known as the Overlay Management Backbones (OMBs). The OMB is a self-organising solution to the problem space in which each OMB node is dynamically assigned a different service context task. The selection of OMB nodes is conducted automatically, without the need of relatively heavy-weighted dynamic negotiations. Our solution relies on the scalability and dynamicity advantages of Distributed Hash Tables (DHTs). This system is needed to select continuously, automatically, and dynamically a set of network nodes, to become responsible for collecting the availability information of service context in the changing network. This solution advances the state of the art avoiding dynamic negotiations between all network nodes reducing management complexity and cost for bandwidth-limited environments.

Integration of Mobile Devices into Popular Peer-to-Peer Networks

Peer-to-peer content-distribution networks are nowadays highly popular among users that have stationary computers with high-bandwidth Internet connections. Mobile devices (e.g. cell phones) that are connected to the Internet via cellular-radio networks, however, could not yet be launched into this field to a satisfactory extent. Although most mobile devices have the necessary hardware resources for joining peer-to-peer content-distribution networks, they are often not able to benefit from participation, due to limitations caused by mobility. In this work, mobile devices are identified as providers of advanced mobile features and services that are usually not available to computers in stationary networks. These mobile features and services can be exchanged for services in peer-to-peer networks, turning mobile devices into valuable trading partners. Partnership schemes are set up to define the way of a fair cooperation between mobile devices and other peers. A novel peer-to-peer architecture is suggested that applies partnership schemes to a well-established peer-to-peer content-distribution network and facilitates the integration of mobile devices.

Energy Efficiency in Future Home Environments: A Distributed Approach

In this paper, a new architecture for sharing resources amongst home environments is proposed. Our approach goes far beyond traditional systems for distributed virtualization like PlanetLab or Grid computing, since it relies on complete decentralization in a peer-to-peer like manner, and above all, aims at energy efficiency. Energy metrics are defined, which have to be optimized by the system. The system itself uses virtualization to transparently move tasks from one home to another in order to optimally utilize the existing computing power. An overview of our proposed architecture is presented as well as an analytical evaluation of the possible energy savings in a distributed example scenario where computers share downloads.

Network Virtualization in Future Home Environments

Home environments have a great potential of resource sharing and energy saving. More and more home computers are running on an always-on basis (e.g. media-centers or file-sharing clients). Such home environments have not been sufficiently analyzed regarding their energy-efficient operation, yet. This paper discusses network virtualization methods that are needed in future home environments to enable the energy-efficient cooperation of home networks. End-users share their available hardware resources (e.g. CPU, disk, or network resources) with other users in an energy-efficient and balanced way. To achieve such an envisioned future home environment, an architecture is suggested that combines different virtualization methods. In this paper, virtualization related requirements of the suggested architecture are discussed in detail. Network virtualization methods and concepts are compared to each other with respect to their usability in the architecture. In addition, initial virtualization approaches are simulated and evaluated with regard to benefits and complexity in the suggested architecture.

Virtualisierung im Future Internet

ZusammenfassungDas Future Internet stellt sich der Herausforderung, die Verknöcherung und die Unzulänglichkeiten des heutigen Internets zu überwinden. Es soll beispielsweise robust, zuverlässig und fehlertolerant sein und dabei Dienste auf energieeffiziente Weise erbringen. Zusätzlich müssen auch neue Anforderungen antizipiert werden, die zukünftige Dienste und Netze stellen, um der Entwicklung von neuen Diensten und Protokollen nicht im Wege zu stehen. Erforderlich ist hierbei die Entwicklung einer äußerst variablen und rekonfigurierbaren Netzwerkarchitektur, die eine möglichst einfache und autonome Netzwerkverwaltung mit einschließt. Die Virtualisierung von Host- und Netzwerkressourcen stellt in diesem Zusammenhang eine der Schlüsseltechnologien dar, mit der diese notwendige Flexibilität erreicht werden kann. Virtualisierung verbirgt die Komplexität von physikalischen Netzwerkinfrastrukturen und stellt homogene, flexible und dynamisch rekonfigurierbare virtuelle Ressourcen zur Verfügung. Dieser Artikel gibt einen Überblick über verschiedene Host- und Netzwerkvirtualisierungsmethoden. An mehreren Beispielen wird aufgezeigt, wie verschiedene Herausforderungen angegangen werden können, die sowohl im heutigen Internet als auch im Internet der Zukunft eine Rolle spielen.

An Economical Cost Model for Fair Resource Sharing in Virtual Home Environments

Home networks recently gain importance due to their development from pure internal networks in form of an Ethernet LAN to converged networks integrating home, Internet, and access provider infrastructure. In emerging future home networking scenarios, service provisioning and network management is proposed by distributed architectures forming virtual home environments (VHEs). This paper provides a service description and corresponding traffic and cost model for fair resource sharing in VHEs. The objective of the proposed cost model is to allow an evaluation of the contribution and consumption for each user participating in the VHE to find an economic balance in the distributed behavior. Hereby, the contribution counts positively and the consumption negatively. The economic balance controls the load balancing in the VHE and further limits the consumption of resources for users which over-pass a corresponding threshold of negative balance leading to an exclusion from the VHE, if the negative balance is not equilibrated over a mean- or long-time horizon.

Towards an Information Model That Supports Service-Aware, Self-managing Virtual Resources

The AUTOI project is creating a virtual communication resource overlay with autonomic characteristics to adapt the services and resources offered to meet changing user needs, business goals, and environmental conditions. Self-knowledge enables the network to reconfigure itself in the face of change to adapt its services according to business goals. The requirements of an information model, to support self-knowledge (concepts, characteristics and behaviour) are presented. This information model plus ontologies provide a common language to represent the self-management of the overlay. This position paper details the requirements in specifying such an information model and language, and describes how the model and language will be used within the project.

An Energy-Efficient Distributed Office Environment

Energy efficiency in the field of information and communication technology becomes increasingly important due to the increase in energy costs and the desire to reduce CO