Showing papers by "Bernard Cousin published in 2012"

Bandwidth reservation in mobile adhoc networks

Abstract: The bandwidth reservation is one of most adopted solutions to meet QoS requirements in 802.11 ad hoc networks. The efficiency of these solutions depends on the accuracy of their estimations of available bandwidth; otherwise, their application can be catastrophic on networks. Therefore, accurate bandwidth estimation is fundamental, where each networks characteristic must be taken into consideration, including mobility and medium sharing. Current solutions do not take into account all networks characteristics, resulting to wrong bandwidth estimations and QoS violations. In this paper, we present a new approach for bandwidth reservation — Accurate Bandwidth Reservation (ABR) — which embeds an improved method of available bandwidth measurement, where all criteria of such networks are considered. Evaluation of ABR is performed by simulations and comparisons with some existing approachs.

Reliable multicast sessions provisioning in sparse light-splitting DWDM networks using p-cycles

Abstract: In this paper, we study the node and link protection using p-cycles for dynamic multicast sessions in all-optical DWDM networks. First, we propose a new concept for protecting nodes of light-trees under the sparse light-splitting and wavelength continuity constraints. Then, we integrate our concept in a novel algorithm, named node and link protecting candidate p-cycles based algorithm with sparse light-splitting constraints (NPCC-SSC). Our algorithm enables both node and link failure recovery in dynamic multicast traffic. Extensive simulations show that the NPCC-SSC algorithm achieves the best resource utilization, and outperforms the existing approaches in terms of blocking probability and computational time.

Tree reconfiguration without lightpath interruption in WDM optical networks

Abstract: Efficient reconfiguration of optical multicast trees in wavelength division multiplexing (WDM) networks is required. Multimedia applications which consume a huge bandwidth, require multicasting. So, multicast concept is extended to optical networks to improve performance. Today, networks are facing many phenomena such as changes in the traffic model, failures, additions or deletions of some network resources due to a maintenance operation. To cope with these phenomena, network operators compute new topology according to the applications requirements. Some real-time multicast applications are not indulgent with lightpath interruptions. So the configuration of the network must be done as quickly as possible to be spontaneously deal with the problem before other events appear and without connection interruption. To the best of our knowledge, there is no work in the literature that considers the reconfiguration of an optical multicast tree to another one without connection interruption. We prove that it is impossible to reconfigure any initial tree into any final tree using only one wavelength and without connection interruption. We propose in this paper BpBAR_2 method, using several wavelengths to reconfigure optical WDM network. This algorithm does tree reconfiguration without lightpath interruption, reduce the reconfiguration setup time and the cost of wavelengths used.

Proactive and reactive collaboration schemes for multi-domain networks monitoring

Abstract: The monitoring of the quality of service in a multi-domain network supervises the multi-domain service performance. A multi-domain service is a service that crosses several domains which can be managed by different providers. Since each domain can be managed with its own policies and may require confidentiality of its topology and its monitoring processes, we propose that the monitoring architecture has to be configurable. In this paper, we propose two collaboration schemes that are based on the reactive and the proactive modes. Both of collaboration schemes allow the multi-domain monitoring architecture to select the measurement points that will participate in the multi-domain monitoring and to configure the selected measurement points. In this paper, we present our proposed collaboration schemes and then we evaluate their performance through extensive simulations using Network Simulator (NS-2).

QoS fault detection and localization mechanisms (FDLM) in multi-domain networks adapted to export methods

Abstract: Monitoring the quality of service in a multi-domain network allows providers to ensure the control of multi-domain service performance. A multi-domain service is a service that crosses multiple domains. In this paper, we propose several mechanisms for fault detection and fault localization. A fault is detected when an end-to-end contract is not respected. Faulty domains are domains that do not fulfill their Quality of Service (QoS) requirements. Our three proposed fault detection and localization mechanisms (FDLM) depend on the export method used. These export methods define how the measurement results are exported for analysis. We consider the periodic export, the triggered export, and a combined method. For each FDLM, we propose two sub-schemes that use different fault detection strategies. In this paper, we describe these mechanisms and evaluate their performance using Network Simulator (NS-2).

Localization of Single Link-Level Network Anomalies

Abstract: Achieving accurate, cost-efficient, and fast anomaly localization is a highly desired feature in computer networks. Prior works, examining the problem of single link-level anomaly localization, have claimed that a necessary condition for localizing anomalies unambiguously is to deploy resources that enable the monitoring of a set of paths distinguishing between all links of the network pairwise. In this paper, we show that the number of pair of links that are to be distinguished can be cut down drastically using an already established anomaly detection solution. This results in reducing the localization overhead and cost significantly. Furthermore, we show that all potential anomaly scenarios can be derived offline from the anomaly detection solution. Therefore, we compute full localization solutions, i.e. monitors that are to be activated and paths that are to be monitored, for all potential anomaly scenarios offline. This results in a significant minimization of the localization delay. We devise an anomaly localization technique that selects monitor locations and monitoring paths jointly; thereby enabling a trade-off between the number and locations of monitoring devices and the quality of monitoring paths. The problem is formulated as an integer linear program (ILP), and is shown to be NP-hard through a polynomial-time reduction from the NP-hard facility location problem. The effectiveness and the correctness of the proposed anomaly localization scheme are verified through theoretical analysis and extensive simulations.

Candidate-cycle-based heuristic algorithm for node-and-link protection of dynamic multicast traffic in optical DWDM networks

Abstract: Maintaining survivability of DWDM networks is crucial to multicast traffic. A link-or-node failure has a severe impact on optical multicast sessions as it can prune several communications simultaneously. In this paper, we present a novel candidate-cycle-based heuristic algorithm for node-and-link protection (CCHN) in dynamic multicast traffic. CCHN is based on p-cycle protection concept. The p-cycle concept ensures a fast restoration time and an efficient use of network capacity. Extensive simulations show that the blocking probability of our algorithm is lowest. Furthermore, the computational time of our algorithm is very low compared with the existing approaches, especially when traffic load is high.

Power fairness for multicast traffic in optical networks with adaptive light splitters

Abstract: To perform data multicasting in the optical layer, optical nodes must be equipped with light splitters. Light splitters can split one light wave to more than one node output. A lot of work had been done in order to enhance the structure of the light splitter in a way to reduce its cost and enhance its performance in terms of the power loss resulted of multiple splitting. To guarantee the fairness of power received by different members of a same multicast group, the use of adaptive light splitters is required. Adaptive light splitters allow splitting an incoming light signal into two or more node output with the ability of varying the individual power of each output signal. This paper studies the benefits of using adaptive splitters on the value of the power received by each of the multicast group members in a way to assure fairness among all members.