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Duelli, M., Meier, S., Wagner, D., Zinner, T., Schmid, M., Hoffmann, M., Kiess, W.: Experimental Demonstration of Network Virtualization and Resource Flexibility in the COMCON Project. 8th International ICST Conference on Testbeds and Research Infrastructures for the Development of Networks and Communities. , Thessaloniki (2012).
In the recent past, Network Virtualization (NV) received much attention. In the beginning, the Future Internet research community was interested in deploying innovative protocols in isolated networks. Then, business models have been developed that separate functions today being united in the Internet Service Provider (ISP) and by that defining a vertically and horizontally divided market. Nevertheless, Virtual Net- works (VNs) are still not available on the market. The consortium of the COntrol and Management of COexisting Networks (COMCON) project examines the potential interactions in such divided market and evaluates the applicability of existing technologies for automated virtualizationenabled network management. To promote the manifold research, a selected scenario was demonstrated at the Euroview 2011. The network virtualization in this scenario is based on Generalized Multi-Protocol La- bel Switching (GMPLS) and allows exible resource provisioning, i.e. the topology and its elements may be changed during life time of the VN. As innovative service we selected a Video on Demand (VoD) service using a Scalable Video Codec (SVC) that allows to route the video on layer granularity. A multi-level multi-tennant monitoring system is used to provide status information on physical as well as on virtual network level. The scenario shows how exible VN provisioning and innovative services may interact across the different players and by that solving challenging situations. All necessary components have been implemented and the selected scenario has been executed on a real network based on Linux PCs. In this paper, we describe the components, the scenario and the insights gained in more detail.
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Felipe Botero, J., Hesselbach, X., Duelli, M., Schlosser, D., Fischer, A., de Meer, H.: Energy Efficient Virtual Network Embedding. IEEE Communication Letters. PP, (2012).
Waste of energy due to over-provisioning and over-dimensioning of network infrastructures has recently stimulated the interest on energy consumption reduction by Internet Service Providers (ISPs). By means of resource consolidation, network virtualization based architectures will enable energy saving. In this letter, we extend the well-known virtual network embedding problem (VNE) to energy awareness and propose a mixed integer program (MIP) which provides optimal energy efficient embeddings. Simulation results show the energy gains of the proposed MIP over the existing cost-based VNE approach.
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Duelli, M.: Heuristic Design and Provisioning of Resilient Multi-Layer Networks, (2012).
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Duelli, M., Schlosser, D., Felipe Botero, J., Hesselbach, X., Fischer, A., de Meer, H.: VNREAL: Virtual Network Resource Embedding ALgorithms in the Framework ALEVIN. 7th Euro-NF Conference on Next Generation Internet Networks (NGI 2011). , Kaiserslautern, Germany (2011).
Network virtualization is recognized as an enabling technology for the Future Internet that overcomes network ossification. However, it introduces a set of challenges. In any network virtualization environment, the problem of optimally mapping virtual resources to physical resources, known as virtual network embedding (VNE), is a critical challenge. Several algorithms attempting to solve this problem have been proposed in literature, so far. However, comparison of existing and new VNE algorithms is hard, as each algorithm focuses on different criteria. To that end, the VNREAL project introduces ALEVIN, a framework to compare different algorithms according to a set of metrics, easily incorporate new VNE algorithms, and evaluate these algorithms on a given scenario for arbitrary parameters.
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Schlosser, D., Duelli, M., Zinner, T., Meier, S., Wagner, D., Barisch, M., Hoffmann, M., Kellerer, W., Schmid, M.: Service Component Mobility Enabled by Network Virtualization. Euroview 2011 (2011).
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Felipe Botero, J., Hesselbach, X., Duelli, M., Schlosser, D., Fischer, A., de Meer, H.: Flexible VNE Algorithms Analysis using ALEVIN. Euroview 2011 (2011).
Network virtualization is recognized as an enabling technology for the Future Internet that overcomes network ossification. However, it introduces a set of challenges. In any network virtualization environment, the problem of optimally mapping virtual demands to physical resources, known as virtual network embedding (VNE), is a crucial challenge. This paper analyses the behaviour of the main algorithms proposed to solve VNE by means of the ALEVIN framework. The VNE algorithms are evaluated with regard to appropriate metrics such as: cost, revenue, and virtual network acceptance ratio. We also analyse the impact of the recently introduced hidden hop demand concept in the performance of the VNE algorithms.
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Jarschel, M., Schlosser, D., Duelli, M., Pries, R.: IPOM: Interactive Proxy Management Tool for Future Communication Networks Using OpenFlow, (2011).
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Schlosser, D., Duelli, M., Goll, S.: Performance Comparison of Common Server Hardware Virtualization Solutions Regarding the Network Throughput of Virtualized Systems. University of Wuerzburg (2011).
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Duelli, M., Ott, J., Qin, X., Weber, E.: MuLaNEO: Eine Software zur Planung und Optimierung von Mehrdienstnetzen, (2011).
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Duelli, M., Ott, J., Qin, X., Weber, E.: MuLaNEO: Planung und Optimierung von Mehrdienstnetzen. PIK - Praxis der Informationsverarbeitung und Kommunikation. 34, 138--139 (2011).
Telekommunikationsanbieter benötigen Netze, die mehrere Dienste/Technologien unterstützen und im Rahmen gegebener Anforderungsprofile ausfallsicher und zugleich kostengünstig sind. Die Planung solcher Netze kann auf ein kombinatorisches Optimierungsproblem mit exponentieller Komplexität zurückgeführt werden. In diesem Beitrag stellen wir eine offene und modulare Software für die vereinfachte Entwicklung und den Vergleich solcher Planungsverfahren vor.
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Schlosser, D., Duelli, M., Goll, S.: Performance Comparison of Hardware Virtualization Platforms. IFIP/TC6 NETWORKING 2011 (NETWORKING 2011). , Valencia, Spain (2011).
Hosting virtual servers on a shared physical hardware by means of hardware virtualization is common use at data centers, web hosters, and research facilities. All platforms include isolation techniques that restrict resource consumption of the virtual guest machines. However, these isolation techniques have an impact on the performance of the guest systems. In this paper, we study how popular hardware virtualization approaches (OpenVZ, KVM, Xen v4, VirtualBox, VMware ESXi) affect the network throughput of a virtualized system. We compare their impact in a dedicated and a shared host scenario as well as to the bare host system. Our results provide an overview on the performance of popular hardware virtualization platforms on commodity hardware in terms of network throughput.
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Fischer, A., Felipe Botero, J., Duelli, M., Schlosser, D., Hesselbach, X., de Meer, H.: ALEVIN - A Framework to Develop, Compare, and Analyze Virtual Network Embedding Algorithms. Electronic Communications of the EASST, Kommunikation in Verteilten Systemen 2011. 37, (2011).
Network virtualization is recognized as an enabling technology for the Future Internet. Applying virtualization of network resources leads to the problem of mapping virtual resources to physical resources, known as “Virtual Network Embedding” (VNE). Several algorithms attempting to solve this problem have been discussed in the literature, so far. However, comparison of VNE algorithms is hard, as each algorithm focuses on different criteria. To that end, we introduce a framework to compare different algorithms according to a set of metrics, which allow to evaluate the algorithms and compute their results on a given scenario for arbitrary parameters.
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Meier, S., Barisch, M., Kirstädter, A., Schlosser, D., Duelli, M., Jarschel, M., Hoßfeld, T., Hoffmann, K., Hoffmann, M., Kellerer, W., Khan, A., Jurca, D., Kozu, K.: Provisioning and Operation of Virtual Networks. Electronic Communications of the EASST, Kommunikation in Verteilten Systemen 2011. 37, (2011).
In today’s Internet, requirements of services regarding the underlying transport network are very diverse. In the future, this diversity will increase and make it harder to accommodate all services in a single network. A possible approach to keep up with this diversity in future networks is the deployment of isolated, custom tailored networks on top of a single shared physical substrate. The COMCON (COntrol and Monitoring of COexisting Networks) project aims to define a reference architecture for setup, control, and monitoring of virtual networks on a provider- and operator-grade level. In this paper, we present the building blocks and interfaces of our architecture.
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Duelli, M.: VNREAL: Virtual Network Resource Embedding ALgorithms in the Framework ALEVIN. , 7th Euro-NF Conference on Next Generation Internet Networks (NGI 2011), Kaiserslautern, Germany (2011).
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Duelli, M., Ott, J., Müller, T.: MuLaViTo: Multi-Layer Visualization Tool, (2011).
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Duelli, M., Schlosser, D., Singeorzan, V., Felipe Botero, J., Hesselbach, X., Diaz Cervantes, L., Fischer, A., Till Beck, M.: ALEVIN: Algorithms for Embedding VIrtual Networks, (2011).
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Duelli, M., Ott, J., Qin, X., Weber, E.: MuLaNEO: Eine Software zur Planung und Optimierung von Mehrdienstnetzen, (2011).
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Duelli, M., Qin, X., Menth, M.: Greedy Design of Resilient Multi-Layer Networks. 6th Conference on Next Generation Internet Networks (NGI 2010). , Paris, France (2010).
In this paper, we propose a deterministic greedy heuristic providing a construction layout for a cost-efficient multi-layer network that is able to carry a given set of traffic demands with and without protection on different layers. We apply the heuristic to different reference network topologies and protection requirements. Evaluations are conducted regarding equipment cost on different layers, blocking probability, path lengths, and number of demands affected by specific failures.
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Duelli, M.: Deferring CAPEX Investments in Multi-Layer Networks through IP Traffic-Dependent Expansion Stages. , 11. ITG-Fachtagung Photonische Netze, Leipzig, Germany (2010).
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Duelli, M.: Routing, Grooming, Resilience, and Resource Management (100GET-E3-R3G). , BMBF/CELTIC Status Meeting 100GET, Stuttgart, Germany (2010).
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Duelli, M., Endler, A., Menth, M.: Deferring CAPEX Investments in Multi-Layer Networks through IP Traffic-Dependent Expansion Stages. 11. ITG-Fachtagung Photonische Netze. p. 133--138. , Leipzig, Germany (2010).
Network design is performed for a traffic load in the future. This traffic load is far greater than traffic loads observed at intermediate stages. In this paper, we propose to plan a multi-layer network for such a future traffic load, but instead of provisioning the full network equipment at once, we suggest to defer the deployment of expensive IP interfaces and other enabling equipment only to stages when they are really needed to carry traffic. We develop an algorithm that concentrates IP traffic at an intermediate stage on a subset of those IP interfaces that are required to carry the full load in the future. This reduces the set of used IP interfaces which need to be installed at intermediate stages, and CAPEX investments for the other equipment can be deferred to the future.
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Duelli, M.: Greedy Design of Resilient Multi-Layer Networks. , 6th Conference on Next Generation Internet Networks (NGI 2010), Paris, France (2010).
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Schlosser, D., Jarschel, M., Duelli, M., Hoßfeld, T., Hoffmann, K., Hoffmann, M., Jochen Morper, H., Jurca, D., Khan, A.: A Use Case Driven Approach to Network Virtualization. accepted at IEEE Kaleidoscope 2010, published via OPUS Würzburg under OpenAccess. , Würzburg (2010).
In today's Internet, services are very different in their requirements on the underlying transport network. In the future, this diversity will increase and it will be more difficult to accommodate all services in a single network. A possible approach to cope with this diversity within future networks is the introduction of support for running isolated networks for different services on top of a single shared physical substrate. This would also enable easy network management and ensure an economically sound operation. End-customers will readily adopt this approach as it enables new and innovative services without being expensive. In order to arrive at a concept that enables this kind of network, it needs to be designed around and constantly checked against realistic use cases. In this contribution, we present three use cases for future networks. We describe functional blocks of a virtual network architecture, which are necessary to support these use cases within the network. Furthermore, we discuss the interfaces needed between the functional blocks and consider standardization issues that arise in order to achieve a global consistent control and management structure of virtual networks.
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Pluntke, C., Menth, M., Duelli, M.: CAPEX-Aware Design of Survivable DWDM Mesh Networks. IEEE International Conference on Communications (ICC). , Dresden, Germany (2009).
This paper reviews the basic architecture and component costs of opaque, transparent, and semi-transparent DWDM networks and looks at the network design problem from a capital expenditure (CAPEX) point of view. Given are a fiber topology and a demand matrix with different bit rates. Required is the least-cost optical equipment for that topology together with the routing and potential muxponder-based aggregation of all demands such that they can be supported by the newly designed network. We look at the problem for networks without resilience requirements and for survivable networks using 1+1 protection against single fiber cuts. We model this problem for the three types of optical networks by integer linear programs (ILPs) in a canonical way.
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Duelli, M., Weber, E., Menth, M.: A Generic Algorithm for CAPEX-Aware Multi-Layer Network Design. 10. ITG-Fachtagung Photonische Netze. p. 167--174. , Leipzig, Germany (2009).
Capital expenditure (CAPEX), i.e. equipment cost, is a decisive criterion for the design of a new network infrastructure. The design of efficient transport networks requires the interconnection of multiple technologies which form separate layers with their own networking view and routing. This leads to the notion of multi-layer networks. CAPEX-aware design of such networks requires algorithms which propose multi-layer hardware configurations that are able to carry a given set of traffic demands at minimal CAPEX. We present a generic algorithm for CAPEX-aware multi-layer network design as well as a computationally viable implementation and perform evaluations on realistic network topologies. The underlying CAPEX and multi-layer technology models are explained in detail.
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Michaelis, T., Duelli, M., Chamania, M., Lichtinger, B., Rambach, F., Türk, S.: Network Planning, Control and Management Perspectives on Dynamic Networking. European Conference and Exhibition on Optical Communication (ECOC). , Vienna, Austria (2009).
Besides the frequently claimed cost savings due to automation, one major advantage of dynamic networking is that this networking paradigm matches the mode of operation which is observed in the Internet and is essential for making transport networks a native part of it. This talk highlights three essential ingredients of dynamic networking: Firstly, network planning creates the required degrees of freedom in the data plane for a dynamic control plane. Secondly, service provisioning and restoration provide the required agility for dynamic network operation, no matter if implemented on the management or on a control plane. Eventually, service management ensures adequate service performance across all involved network domains. We conclude that all of these aspects need to be addressed adequately in order to realize dynamic networking.
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Hoßfeld, T., Duelli, M., Staehle, D., Tran-Gia, P.: Chapter VIII: Cooperation Strategies for P2P Content Distribution in Cellular Mobile Networks: Considering Mobility and Heterogeneity. In: Seet, B.-C. (ed.) Mobile Peer-to-Peer Computing for Next Generation Distributed Environments: Advancing Conceptual and Algorithmic Applications. p. 1234--5678. Information Science Reference, ISBN: 978-1-60566-715-7 (2009).
The performance of P2P content distribution in cellular networks depends highly on the cooperation and coordination of heterogeneous and often selfish mobile users. The major challenges are the identification of problems specifically arising in cellular mobile networks and the development of new cooperation strategies to overcome these problems. In the coherent previous chapter, we focused on the selfishness of users in such heterogeneous environments. This discussion is now extended by emphasizing the impact of mobility and vertical handover between different wireless access technologies. An abstract mobility model is required to allow the performance evaluation in feasible computational time. As a result, the performance in today’s and future cellular networks is predicted and new approaches to master heterogeneity in cellular networks are derived.
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Menth, M., Duelli, M., Martin, R., Milbrandt, J.: Resilience Analysis for Packet-Switched Communication Networks. IEEE/ACM Transactions on Networking. 17, (2009).
In the presence of local network outages, restoration and protection switching mechanisms redirect the traffic over alternative paths to mitigate the effect of failures. However, some failure combinations still lead to loss of ingress-egress connectivity within a network or to severe congestion due to rerouted traffic. Congestion may also be caused by unexpected traffic shifts due to changed user behavior or due to changes of interdomain routing. This paper presents a framework for the analysis of ingress-egress unavailability and congestion due to (1) failures, (2) changes of user behavior, and (3) changed interdomain routing. It proposes algorithms to find the most probable combinations of (1), (2), and (3), and to evaluate the connectivity and the relative link load of the network under these conditions. We have implemented this concept in a software tool and its visualization of the results leads to a comprehensive view of the network’s resilience. It helps to anticipate potential ingress-egress disconnection and congestion before failures and overload occur or before planned modifications (new infrastructure, new routing, new customers) take effect. Thus, it detects weak points in a network, predicts the effectiveness of potential upgrades, and thereby supports careful bandwidth overprovisioning.
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Duelli, M., Weber, E., Menth, M.: A Framework for Multi-Layer Network Design in 100GET-E3-R3G, (2009).
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Duelli, M.: A Generic Algorithm for CAPEX-Aware Multi-Layer Network Design. , 10. ITG-Fachtagung Photonische Netze, Leipzig, Germany (2009).
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Duelli, M.: Routing, Grooming, Resilience, and Resource Management (100GET-E3-R3G). , BMBF/CELTIC Status Meeting 100GET, Dresden, Germany (2009).
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Duelli, M.: Performance Evaluation of IP over Cost-Optimized Optical Multilayer Networks with SRLGs. , 9. ITG-Fachtagung Photonische Netze, Leipzig, Germany (2008).
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Dzida, M., Zagozdzon, M., Zotkiewicz, M., Pióro, M., Pettersson, M.P., Duelli, M., Menth, M.: Three Methods for Optimizing Single-Shortest Path Routing. 4th Euro-NGI Conference on Next Generation Internet Networks (NGI 2008). , Krakow, Poland (2008).
Intra-domain routing in IP networks is based on the shortest path principle by assigning administrative weights (costs) to links. The resulting least-cost paths determine routes between pairs of routers. If several such equal-cost paths exist between a pair of routers, it may not be clear which of them is actually used to route traffic. This makes it difficult to predict the network traffic flow distribution. Therefore, the selected link costs should assure uniqueness of the shortest paths. On top of that, the link costs can be optimized with respect to some traffic objective. The resulting optimization problem, referred to as SSPP, turns out to be N P-hard. SSPP can be formulated as a mixed-integer programming problem and, as such, solved with branch-and-bound (B&B). In this paper, we consider three methods for SSPP. Two of them are exact methods based on B&B, namely branch-and-cut and constraint programming. Since the exact solutions of SSPP may require excessive computation time and may not always be effective when applied to practical networks, we also study a fast heuristic method. Finally, in a numerical study, we compare the effectiveness of the three approaches.
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Duelli, M., Pluntke, C., Menth, M.: Minimizing Installation Costs of Survivable DWDM-Mesh Networks: A Heuristic Approach. 4th Euro-NGI Conference on Next Generation Internet Networks (NGI 2008). p. 15--22. , Krakow, Poland (2008).
The cost function for the capacity of optical links follows a step function. That means, the support of one more lightpath might require a costly upgrade of an optical cross connect (OXC), but then additional lightpaths can be supported at almost no further cost. This should be considered when lightpaths are routed through an optical network. In this paper we optimize the routing of the lightpaths to minimize the costs for the required optical equipment. We consider this problem for the failure-free case only and for survivable networks using dedicated path protection. We formulate the problems by integer linear programs (ILPs). In addition, we propose heuristics to solve the problem since solving ILPs is computationally expensive and not feasible for large problem instances. We show that our heuristics lead to good results within a fraction of time compared to ILP solvers.
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Duelli, M., Hartmann, M., Menth, M., Hülsermann, R., Düser, M.: Performance Evaluation of IP over Cost-Optimized Optical Multilayer Networks with SRLGs. 9. ITG-Fachtagung Photonische Netze. p. 21--29. , Leipzig, Germany (2008).
The design of optical transport and IP networks is investigated with respect to the effect on overall network perfor mance when the two aspects are combined in the same network architecture. The focus is on the identification of advantages in the joint design of IP and transport networks, as well as on the shortcomings and network bottlenecks which may result from sub-optimal design. The impact of different IP routing strategies (shortest path, equal-cost multipath) on the network utilization is quantified, and potential sources for overload in the IP domain are determined. Simulations were carried out to systematically assess technical metrics like link utilization and economic parameters such as cost for a 50-node transport network with line rates up to 40 Gbit/s. The impact of fiber cuts was taken into account, leading to multiple logical IP links to fail simultaneously, i.e. shared risk link groups (SRLGs), and triggering massive IP rerouting. Applying the results allows to identify bottlenecks in the design, and to devise mechanisms which allow cost-optimal network design of future IP and optical transport networks.
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Duelli, M.: 100GET-E3-R3G Kick-Off Presentation. , 100GET Kick-Off Meeting, Berlin, Germany (2008).
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Duelli, M.: Resource Management in Resilient Multilayer Networks. , BMBF/CELTIC Status Meeting 100GET and EIBONE, Hamburg, Germany (2008).
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Duelli, M.: CAPEX-Aware Multi-Layer Network Design. , Workshop der ITG-Fachgruppe 5.2.1 "Systemarchitektur und Traffic Engineering", Munich, Germany (2008).
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Duelli, M.: Modeling and Impact of Mobility on P2P Systems in Wireless Networks, (2007).
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Duelli, M.: Impact of Vertical Handovers on Cooperative Content Distribution Systems. , Seventh IEEE International Conference on Peer-to-Peer Computing (P2P2007), Galway, Ireland (2007).
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Duelli, M., Hoßfeld, T., Staehle, D.: Impact of Vertical Handovers on Cooperative Content Distribution Systems. Seventh IEEE International Conference on Peer-to-Peer Computing (P2P2007). p. 177--184. , Best Student Paper, Galway, Ireland (2007).
In this paper, we evaluate the performance of a P2P-based content distribution system in heterogeneous, wireless networks. The mobile users coordinate each other with cooperation strategies enabled by the multi-source download mechanism, as in eDonkey or BitTorrent. Due to the mobility, vertical handovers between different wireless access technologies are required which may result in transmission delays and IP address changes of the switching peer. Hence, connections among users have to be reestablished and downloading users are requeued at a providing peer’s waiting queue. In detail, we investigate the impact of requeueing with each VHO as well as the use of mechanisms that preserve the IP address and connections beyond VHOs, like MobileIP. Another important phenomenon occurring with VHOs is the abrupt change of the available bandwidth, e.g., from a fast WLAN connection to a rather slow UMTS connection. We evaluate the download times for files by means of simulation while considering different load scenarios in today’s and future network layouts of the B3G network. As a result of the performance evaluation, we derive a new time-based cooperation strategy that counters the impact of mobility. Instead of downloading individual blocks of a file, a user gets a time slot at a providing peer. We show that this leads to a significant performance gain.
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Duelli, M., Hoßfeld, T., Staehle, D.: Impact of Vertical Handovers on Cooperative Content Distribution Systems. University of Wuerzburg (2007).
