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Next Generation Internet Networks, 3rd EuroNGI Conference on

Date 21-23 May 2007

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Displaying Results 1 - 25 of 43
  • Covers

    Page(s): C1
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  • [Copyright notice]

    Page(s): ii
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  • NGI 2007 Contents

    Page(s): iii - v
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  • Message from the Chairman

    Page(s): vii
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  • Message from the Technical Program Chairmen

    Page(s): viii
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  • Organization-Executive Committee

    Page(s): ix
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  • Technical Program Committee

    Page(s): x - xi
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  • list-reviewer

    Page(s): xii - xiii
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  • IETF: The Next Generation - what is a generation, anyway?

    Page(s): xv
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    The term "generation" is used heavily, usually with the idea that there can be fundamental changes to the way in which things work. Some fundamental changes have happened, and caused great upheavals in the way we manage our daily lives - other things that have been labelled "next generation" have vanished without a trace. This talk focuses on how standards processes interact with the concept of radical change, and aims to show some of the mechanisms that act to enable, encourage or discourage radical changes in technology. View full abstract»

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  • Trends towards Next Generation Internet

    Page(s): xvi - xvii
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    In recent years we can witness a new wave of activities and projects to explore different paths towards Next Generation Internet. After the decade where the Internet Protocol becomes mainstream in communication networks integrating and carrying all new types of services with increasing traffic volume and complexity, there are rising concerns whether the aging Internet protocol architecture with its underlying legacy routing algorithms, control and security mechanisms would soon collapse under the load of new applications and the rapid change of traffic patterns and service generation paradigms in the next decade. In the talk we will focus on trends and evolution paths towards the Next Generation Network. The talk will discuss these trends together with issues of system performance and stochastic scalability, which are current topics of intensive research. These issues are crucial to dimension networks and applications, both from network provider and equipment manufacturer viewpoints. Some observations on future services will commence the talk. It will discuss the notion of Multi-Network Services, i.e. the paradigm shift from a network-centric view to a applicationcentric view. In the current existence of several wireless and wireline networks (PSTN, UMTS, WiMAX, etc.) users of different networks can install service-enabling software and start a new type of service in a short time scale and in a very dynamic way (e.g. VoIP platforms like Skype, software distribution schemes like Bittorrent, etc.). Those services are multi-networks services, which correspond to the term of Edge-based Intelligence. View full abstract»

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  • Network Architecture Evolution: towards "All-IP"

    Page(s): xviii - xix
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    New services, new applications, new profiles of clients, new networking technologies and new forms of communications, such as peer-to-peer, and media/content-to-person, are all driving the need for a converged all-IP network that can provide an "agnostic" layer between the service and transport layers. Designing and realizing such an IP-based network architecture require a through understanding not only of IP networking technology, but also the particular demands of delivering high-performance, real-time services in a way that maintains the telecom grade performance; which means high-reliability and high-quality of traditional telecommunications services. The talk reviews the main technical challenges that allow the network to evolve towards a telecom-quality IP-based network, and discusses the main research issues relating to that. Specifically, on one hand IP technology is the enabler of adaptive and flexible connectivity. Its connectionless structure, with its logical connectivity, provides new levels of scalability and manageability that can't be matched by the "hard-wired" connection-oriented links of legacy transport systems. Actually, the ability of IP makes a much-needed future-proofing, insulating layer between the services above and the diverse transport technologies below; especially when services and transport technologies are both evolving rapidly. On the other hand, the generality of IP compared with the more-tailored-made transmission technologies it is replacing, such as TDM and ATM, also presents challenges when migrating the often QoS-sensitive and critical applications on to IP. To avoid putting at risk existing revenue streams, the new technology must live up to telecom standards and deliver telecom quality. View full abstract»

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  • Accuracy Evaluation of Application-Level Performance Measurements

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (310 KB) |  | HTML iconHTML  

    In many cases, application-level measurements can be the only way for an application to evaluate and adapt to the performance offered by the underlying networks. Applications perceive heterogeneous networking environments spanning over multiple administrative domains as "black boxes" being inaccessible for lower-level measurement instrumentation. However, application-level measurements can be inaccurate and differ significantly from the lower-level ones, amongst others due to the influence of the protocol stacks. In this paper we quantify and discuss such differences using the Distributed Passive Measurement Infrastructure (DPMI), with Measurement Points (MPs) instrumented with DAG 3.5E cards for the reference link-level measurements. We shed light on various impacts on timestamp accuracy of application-level measurements. Moreover, we quantify the accuracy of generating traffic with constant inter-packet-times (IPTs). The latter is essential for an accurate emulation of application-level streaming traffic and thus for obtaining realistic end-to-end performance measurements. View full abstract»

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  • Relying on randomness PlanetLab experiments with distributed file-sharing protocols

    Page(s): 6 - 13
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (498 KB) |  | HTML iconHTML  

    In this paper we present and evaluate a fully distributed file-sharing system architecture. Initially, a seeder node splits a large file into moderate-sized chunks and offers it for download. The seeder and all peers interested in downloading the file join a Chord-based overlay and contact each other randomly for chunk transfers. We report and discuss PlanetLab tests on this system as well as on our modified Chord implementation which it is based on. We give an algorithm for finding uniformly random peers in the overlay and another for estimating the distribution of chunk copies. Both algorithms turn out to have a significant effect on the performance, the first one in particular. View full abstract»

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  • Design and development of a DS-TE experimental testbed with Point-to-Multipoint LSP support

    Page(s): 14 - 20
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    Nowadays, many IP backbone networks adopt separate control and forwarding planes for unicast and multicast traffic flows. Indeed, while MPLS (multiprotocol label switching) is widely deployed for unicast traffic, IP multicast is the only available solution for the delivery of "one-to-many" traffic flows. With P2MP LSPs (Point-to-Multipoint Label Switched Paths) support, a unified control and forwading plane may be devised. Such a reduction in the number of protocols used in the core of the network as well as in the number of encapsulations in the data plane, results in simplified network operations. The paper discusses the design and the development of the control and data planes extensions needed to provide P2MP LSP support in an MPLS network. In particular, such signalling and forwarding mechanisms have been implemented in a network testbed based on open-source routers. Finally, tests have been performed to assess the new mechanisms from both an operational and performance point-of-view. View full abstract»

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  • Improving Web Prefetching by Making Predictions at Prefetch

    Page(s): 21 - 27
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    Most of the research attempts to improve Web prefetching techniques have focused on the prediction algorithm with the objective of increasing its precision or, in the best case, to reduce the user's perceived latency. In contrast, to improve prefetching performance, this work concentrates in the prefetching engine and proposes the Prediction at Prefetch (P@P) technique. This paper explains how a prefetching technique can be extended to include our P@P proposal on real world conditions without changes in the web architecture or HTTP protocol. To show how this proposal can improve prefetching performance an extensive performance evaluation study has been done and the results show that P@P can considerably reduce the user's perceived latency with no additional cost over the basic prefetch mechanism. View full abstract»

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  • A generic approximate transient analysis applied to a priority queue

    Page(s): 28 - 35
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    In this paper, we develop an efficient method to approximate the transient behavior of queueing systems. More precisely, it is shown how singularity analysis of a known transform function of a transient sequence leads to an approximation of this sequence. To illustrate our approach, the transient system contents of both classes in a two-class discrete-time priority queue are investigated. By means of some numerical examples, we then validate our approximations and demonstrate the usefulness of our approach. View full abstract»

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  • Why VCG auctions can hardly be applied to the pricing of inter-domain and ad hoc networks

    Page(s): 36 - 39
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (137 KB) |  | HTML iconHTML  

    The use of Vickrey-Clarke-Groves (VCG) auction mechanisms is gaining popularity in the networking community, where it seems compulsory to incentivize selfish nodes (in ad hoc networks) or domains (in inter-domain communications) to forward the traffic of their peers. Indeed, VCG auctions are known to both be efficient and produce proper incentives. In this note, we argue that, in fact, VCG auctions can hardly be applied to those problems, for different reasons depending on the model studied: 1. If some resource constraints (bandwidth, spectrum, and/or power) have to be taken into account, then computing allocations and prices implies solving optimization problems that are computationally hard for general network topologies. 2. If there are no such resource constraints, then VCG auctions, even if verifying many important and satisfactory properties, cannot verify a major one that is budget balance: the sum of subsidies given to relay nodes exceeds the sum of charges paid by traffic senders. This means that the auction regulator is required to continuously inject money to make the scheme work, which is unlikely to happen. In a second step, we discuss the combinations of properties that can be verified together, and prioritize them for finding out a proper pricing scheme. View full abstract»

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  • Real-Time ARQ Protocol for Improved Impulsive Noise Robustness of ADSL Systems

    Page(s): 40 - 47
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB) |  | HTML iconHTML  

    Impulsive noise robustness is one of the major challenges for the support of new kinds of services like video transmission via ADSL access networks. This paper investigates the application of a real-time ARQ protocol at the ADSL physical layer as an alternative to standardised forward error correction in combination with interleaving. Simulation results based on an impulsive noise model derived from field measurements show that ARQ provides significantly better error correction capabilities with the same overhead and lower end-to-end delay than FEC/interleaving. The best results can be achieved by using a second retransmission option ("second chance option") with sufficient temporal de-coupling to the original disturbance event. It is therefore strongly recommended to introduce ARQ in future standards and ADSL system implementations. View full abstract»

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  • Protocol stack and capacity modeling for WLAN

    Page(s): 48 - 55
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (580 KB) |  | HTML iconHTML  

    Queuing theoretical modeling is a commonly used method for load/capacity analyses of computer networks. This work presents a model for WLAN. In contrast to other works that offer analytical models aiming at general insights to WLAN MAC properties (e.g. [6-9]), an empirical model for capacity analysis under concrete load conditions was developed. The model accounts for relevant communication problems on the OSI-layers 1-4. The presented work appeared within the scope of the network design environment CANDY Framework as one of multiple contributions under the subject ,,Wireless networks and their dimensioning". View full abstract»

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  • Seamless Connectivity in WLAN and Cellular Networks with Multi Criteria Decision Making

    Page(s): 56 - 63
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (204 KB) |  | HTML iconHTML  

    The evolution of today's wireless and mobile technologies and personalized hand-held devices has increased the challenge to handle the trade-off between mobility, performance and cost. The user simply needs to be Always Best Connected (ABC). To make this happen, different types of criteria reflecting relevant characteristics of wireless and mobile access networks such as WLAN, UMTS and GPRS have to be established and judged. In this paper the criteria are divided into three main groups, performance, cost and accessibility. The criteria are fed into a Multi-Criteria Decision Making (MCDM) tool which is able to deliver a ranking of network links in order to become ABC. Finally, a case study with two different Generic Services (GSs) illustrates the decision making process and its outcomes in different situations. View full abstract»

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  • Cooperative Resource Management by Access Points and Stations for Fair and Efficient Sharing of Wireless LANs

    Page(s): 64 - 71
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    The future network will consist of heterogeneous ones, and wireless networks will play a more important role there in providing pervasive services. Our major concern is to develop a way of achieving efficient and fair share of resources in the wireless network, which is built of various equipments. In this regard, one of the significant issue for each station (STA) is how to select an appropriate access point (AP) among available APs in the wireless LANs in order to effectively use those multiple APs, namely, which STA should be accommodated by which AP. In the systems widely deployed currently, each STA straightforwardly and autonomously selects its AP based upon received signal strength (RSS). However, this can result in a concentration of STAs at specific APs, and thus degrade the fairness property in achievable throughput of each STA. We have already proposed a cooperative scheme for APs and STAs in order to attain efficient and fair sharing of resources, and have developed the prototype system. APs provide some information on resource utilization, i.e., the number of active STAs, while STAs autonomously select their appropriate APs by using both the information and RSS. In the present paper, we further investigate two cooperative resource management schemes; in both schemes, each AP broadcasts information on the number of active STAs at fixed time intervals. In one scheme, the information provided is based upon just a single snapshot measurement (SSM) for a particular duration, while it is based on the exponentially weighted moving average with flip-flop filter (EWMA/FF) in the other scheme. EWMA/FF moderates the information to avoid having too many STAs concentrating at specific APs if that changes drastically, while EWMA/FF behaves like SSM otherwise. This successfully leads to fair and efficient sharing of wireless resource. View full abstract»

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  • Survivable Routing of Unicast and Anycast Flows in MPLS Networks

    Page(s): 72 - 79
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    Most of previous research in anycasting has been focused on best-effort networks and IP networks. In contrast, we propose a QoS-based routing of anycast demands in connection-oriented MPLS network. Since in real networks different kinds of flows are transmitted over the same links, we assume that both unicast and anycast requests must be served in the network. Survivability of the network is one of the most important elements of QoS parameters since network failures can lead to significant consequences. We examine performance of several constraint-based algorithms for anycast server selection and QoS unicast routing algorithms. As the performance metric we use the flow lost due to a single failure of the link. For network restoration of anycast flows we propose a new scheme called backup server. Simulations show that application of backup server approach can significantly improve the network survivability. View full abstract»

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  • Applying OD Cycles to Multi-domain, Multi-service Survivable Networks

    Page(s): 80 - 87
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    The origin-destination (OD) cycles approach is applied in this paper to heterogeneous networks, with regard to topologies and services. Decomposition of these networks is performed through gateways that are consequently part of OD cycles associated with inter-domain survivable traffic. Route-diverse cycle parts, called Y and X, are defined to establish cross-domain OD cycles for cases where two gateways are shared between neighboring domains. An intra-domain network model for optimal assignment of resources that meets multiple qualities of protection is developed. Based on some practical observations, the model leads to global optimality. Traditional transport features, such as single and dual node interchange, at gateways and between gateways (respectively), can be considered to cope with independent multi-failure scenarios when limiting a single failure to its own network domain. View full abstract»

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  • Analyzing the file availability and download time in a P2P file sharing system

    Page(s): 88 - 95
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (202 KB) |  | HTML iconHTML  

    In this paper we study the performance of P2P file sharing systems. We are especially interested in how the division of the file into chunks as well as the used chunk selection policy influence on two performance metrics, named the availability and mean download time of the file. We propose a detailed Markov chain model that allows estimating the mean lifetime of the system and comparing different chunk selection policies exactly. In addition, we use simulations to evaluate more complex systems. Results suggest that splitting the file from one chunk into two chunks improves the performance of the system significantly. Meanwhile, the superiority of a chunk selection policy depends on many factors, such as the arrival rate of the new downloaders and service time distribution. View full abstract»

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  • On the relationship between the algebraic connectivity and graph's robustness to node and link failures

    Page(s): 96 - 102
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (350 KB) |  | HTML iconHTML  

    We study the algebraic connectivity in relation to the graph's robustness to node and link failures. Graph's robustness is quantified with the node and the link connectivity, two topological metrics that give the number of nodes and links that have to be removed in order to disconnect a graph. The algebraic connectivity, i.e. the second smallest eigenvalue of the Laplacian matrix, is a spectral property of a graph, which is an important parameter in the analysis of various robustness-related problems. In this paper we study the relationship between the proposed metrics in three well-known complex network models: the random graph of Erdos-Renyi, the small-world graph of Watts-Strogatz and the scale-free graph of Barabasi-Albert. From (Fielder, 1973) it is known that the algebraic connectivity is a lower bound on both the node and the link connectivity. Through extensive simulations with the three complex network models, we show that the algebraic connectivity is not trivially connected to graph's robustness to node and link failures. Furthermore, we show that the tightness of this lower bound is very dependent on the considered complex network model. View full abstract»

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