2013

• IC-13-32 pdf bib
  Trade-off Between Bandwidth and Energy Consumption Minimization in Virtual Network Mapping.
  Esteban Rodriguez, Gustavo Alkmim, Daniel Batista, and Nelson da Fonseca.
  October 2013. In English, 13 pages.
  Abstract: Network virtualization is a promising technology for the Internet of the Future. Nevertheless, an open issue in virtualization is to satisfy the control of resources in a way that energy savings are achieved. This paper introduces a model for the mapping of virtual networks onto network substrates which aims to reduce the energy consumption as well as to reduce the bandwidth consumption. This model is based on an integer linear programming formulation and several parameters, corresponding to characteristic of real networks, are considered. The trade-off between energy and bandwidth consumption is analyzed based on results derived via simulation.

• IC-13-31 pdf bib
  Live Migration in Green Virtualized Networks.
  Esteban Rodriguez, Gustavo Alkmim, Daniel Batista, and Nelson da Fonseca.
  October 2013. In English, 12 pages.
  Abstract: Network virtualization is a promising technology for the Internet of the Future. An open issue in virtualization is the management of network resources in a way that energy savings are achieved without compromising the Quality of Service (QoS) requirements of the virtual networks. The dynamic allocation and deallocation of virtual networks can lead the state of the substrate to a less than optimum energy consumption. This paper introduces two algorithms for the migration of virtual routers and/or links which aims to allocate resources so that energy consumption is minimized. The efficacy of the migration of virtual routers and/or links and its impact on energy consumption are analyzed based on results derived via simulations.

• IC-13-30 pdf bib
  Green Virtualized Networks.
  Esteban Rodriguez, Gustavo Alkmim, Daniel Batista, and Nelson da Fonseca.
  October 2013. In English, 14 pages.
  Abstract: The Future Internet demands energy efficient communication to cope with the ever increasing power consumption. Virtualization techniques have proved to be effective in reducing power consumption of network devices. An open issue in virtualization for green networking is the search for an energy-efficient mapping of virtual networks onto physical networks. This paper introduces a new model for the mapping of virtual networks which aims at reducing the energy consumption. This model is based on an integer linear programming formulation and several parameters, corresponding to characteristic of real networks, are considered. Simulation results attest the efficacy of the proposal.

• IC-13-29 pdf bib
  Approximated Algorithms for Mapping Virtual Networks on Network Substrates.
  Gustavo Alkmim, Daniel Batista, and Nelson da Fonseca.
  October 2013. In English, 14 pages.
  Abstract: Network virtualization is a promising technique for building the Internet of the future since it enables the introduction of new features into network elements at low cost. An open issue in virtualization is how to search for an efficient mapping of virtual network elements onto those of the existing physical network. Mapping is an NP-hard problem and existing solutions take long time to find a solution. This paper presents four new approximated algorithms based on two integer linear programming formulations that runs fast and, also, consider various real network characteristics, which is neglected by other proposals in the literature.

• IC-13-28 pdf bib
  Optimal Mapping of Virtual Networks.
  Gustavo Alkmim, Daniel Batista, and Nelson da Fonseca.
  October 2013. In English, 15 pages.
  Abstract: Network virtualization is a promising technique for building the Internet of the future since it enables the low cost introduction of new features into network elements. An open issue in virtualization is how to search for an efficient mapping of virtual network elements onto those of the existing physical network, also called the substrate network. Mapping is an NP-hard problem and existing solutions ignore various real network characteristics in order to solve problem in a reasonable time frame. This paper introduces two new algorithms for the solution of the mapping problem, both based on 0–1 integer programming, for the solution of the mapping problem which consider a whole new set of network parameters not taken into account by previous proposals. Simulation experiments confirm the efficiency of the proposed algorithms.

• IC-13-25 pdf bib
  Alternative Routing and Zone-Based Spectrum Assignment Algorithm for Flexgrid Optical Networks.
  Rafael A. Scaraficci and Nelson L. S. da Fonseca.
  October 2013. In English, 13 pages.
  Abstract: In optical flexgrid networks, the optical spectrum can be allocated at a much finer granularity that it can be allocated in fixed-grid WDM networks, and connections can use a variable number of slots. However, the dynamic establishment and tear down of lightpaths demanding variable spectrum widths yields to the fragmentation of the spectrum with increase in blocking of connections; mainly connections demanding large spectrum widths. This papers proposes a novel algorithm that introduces a zone-based assignment policy together with an alternative path routing mechanism based on the maximum capacity available. Results derived via simulation using different topologies and considering connections requests from 40Gbps to 1000Gbps, show that the proposed algorithm leads to blocking ratio consistently lower than those given by traditional approaches. Furthermore, it reduces the blocking ratio of high rates connections, in some cases, in more than six times.

• IC-13-24 pdf bib
  Fragmentation Aware Routing and Spectrum Assignment Algorithm.
  Pedro M. Moura - Nelson L. S. da Fonseca - Rafael A. Scaraficci.
  October 2013. In English, 11 pages.
  Resumo: In flex-grid (elastic) networks, the spectrum can be allocated at a much finer granularity than it can be allocated in WDM networks. However, the dynamic establishment and tear down of lightpaths yields to the fragmentation of the spectrum with consequent increase in blocking of requests for connection establishment. Therefore, it is of paramount importance that allocation decisions try to mitigate the fragmentation problem. In line with that, this paper introduces the Multigraph Shortest Path Algorithm for novel Routing and Spectrum Allocation (RSA) in elastic networks. Results indicate that the joint use of the new algorithm with proposed cost functions can produce bandwidth blocking ratio four orders of magnitude lower than existing RSA algorithms.

• IC-13-23 pdf bib
  Algorithm for FIPP p-cycle Path Protection in Flexgrid Networks.
  Helder M. N. S. Oliveira - Nelson L. S. da Fonseca.
  October 2013. In English, 12 pages.
  Abstract: In optical networks, faults in links and nodes cause massive loss of data even if for short periods. Therefore, protection techniques have been developed to cope with failures. Among these techniques, p-cycle is very attractive since it provides ring-like speed of restoration in mesh topologies. In recent years, the technology of flexgrid networks has emerged as a solution for dealing with the diversity of bandwidth demands of network applications. However, very few investigations have been proposed for path protection in flexgrid networks. This paper introduces a novel algorithm to provide Failure-independent path protecting p-cycle for path protection in flexgrid networks. Results indicate that the 100% protection for single failures provided by the algorithm produces low overhead under different scenarios and provide protection for dual failures at a certain extend in networks with large connectivity.

• IC-13-03 pdf bib
  Statistical Multiplexing of Multifractal Flows.
  Cesar A. V. Melo and Nelson L. S. da Fonseca.
  February 2013. In English, 14 pages.
  Abstract: This paper introduces the computation of an expression for the time at which the length of a queue fed by several multifractal flows reaches its maximum. Expressions for the equivalent bandwidth of an aggregate of multifractal flows is also presented. Moreover, it is shown that modelling based on monofractal process rather than based on multifractal processes leads to overprovisioning of resources.

• IC-13-02 pdf bib
  An Envelope Process for Multifractal Traffic Modeling.
  Cesar A. V. Melo and Nelson L. S. da Fonseca.
  February 2013. In English, 13 pages.
  Abstract: In this paper, a novel envelope process for multifractal traffic modeling is introduced. The envelope process is an upper bound for the amount of work arrived in a multifractal Brownian motion process. The time scale of interest of a queueing system fed by a multifractal stream is computed. Simulation experiments using both real and synthetic data show that the proposed model is accurate.

2012

• IC-12-17 pdf bib
  Peer-to-Peer IPTV Services.
  Daniel A. G. Manzato and Nelson L. S. da Fonseca.
  June 2012. In English, 12 pages.
  Abstract: IPTV promises to be within the spectrum of services offered in the future Internet. In cooperative IPTV, clients' resources are typically used to build a scalable system to distribute TV content. One of the major challenges of this approach is to reach the same quality of service of traditional television and commercial IPTV by employing only best effort network layer services. This paper proposes a novel architecture based on P2P networking for cooperative IPTV. Challenges are discussed and some solutions are proposed as part of the architecture. The aim is to make this type of system more competitive with traditional television and commercial IPTV.

• IC-12-16 pdf bib
  An Incentive Mechanism for Peer-to-Peer Networks with Live Streaming.
  Daniel A. G. Manzato and Nelson L. S. da Fonseca.
  June 2012. In English, 14 pages.
  Abstract: Although peer-to-peer networks are more scalable than client-server ones, they face efficiency challenges. One of them is the selfish behavior of non-cooperative peers. Another challenge is the short time peers stay connected to the system, which causes disruptions of the delivery of time-constrained content. This paper introduces an incentive mechanism to address both problems in peer-to-peer networks with live streaming.

• IC-12-13 pdf bib
  Performance Evaluation of a Scheduler for the ONU-BS of Integrated EPON-WiMAX Networks.
  Mariana Piquet Dias and Nelson Luis Saldanha da Fonseca.
  May 2012. In English, 12 pages.
  Abstract: The integration of WiMAX networks with EPON networks combine the large bandwidth availability in optical access networks with the mobility provided by wireless technologies. In this integration, a WiMAX bandwidth scheduler that takes into account the variability of the channel capacity provided by the EPON scheduler is quite important, since the granted bandwidth must be sucient to support the QoS of WiMAX connections. This paper evaluates the performance of a standard-compliant WiMAX uplink scheduler designed to the ONU-BS. The evaluation is conducted using integrated simulators for the WiMAX and for the EPON components. Simulation results show that the proposed scheduler is able to provide QoS to the subscriber stations.

• IC-12-12 pdf bib
  Robust hybrid mechanisms for scheduling of grid tasks.
  Rafael Lima Curi, Daniel Macedo Batista, and Nelson Luis Saldanha da Fonseca.
  May 2012. In English, 14 pages.
  Abstract: This paper proposes three new hybrid mechanisms for the scheduling of grid tasks, which integrate reactive and proactive approaches. They differ by the scheduler used to define the initial schedule of an application and by the scheduler used to reschedule the application. The mechanisms are compared to reactive and proactive mechanisms. Results show that hybrid approach produces performance close to that of the reactive mechanism, but demanding less migrations.

• IC-12-06 pdf bib
  Scheduling Grid Tasks in Face of Uncertain Communication Demands.
  Daniel M. Batista and Nelson L. S. da Fonseca.
  December 2011. In English, 26 pages.
  Abstract: Grid scheduling is essential to Quality of Service provisioning as well as to efficient management of grid resources. Grid scheduling usually considers the state of the grid resources as well application demands. However, such demands are generally unknown for highly demanding applications, since these often generate data which will be transferred during their execution. Without appropriate assessment of these demands, scheduling decisions can lead to poor performance. Thus, it is of paramount importance to consider uncertainties in the formulation of a grid scheduling problem. This paper introduces the IPDT-FUZZY scheduler, a scheduler which considers the demands of grid applications with such uncertainties. The scheduler uses fuzzy optimization, and both computational and communication demands are expressed as fuzzy numbers. Its performance was evaluated, and it was shown to be attractive when communication requirements are uncertain. Its efficacy is compared, via simulation, to that of a deterministic counterpart scheduler and the results reinforce its adequacy for dealing with the lack of accuracy in the estimation of communication demands.

• IC-12-05 pdf bib
  Robust Scheduler for Grid Networks.
  Daniel M. Batista, André C. Drummond, and Nelson L. S. da Fonseca.
  December 2011. In English, 11 pages.
  Abstract: Imprecise input data imposes additional challenges to grid scheduling. This paper introduces a novel scheduler based on fuzzy optimization called IP-FULL-FUZZY which considers uncertainties of both application demands and of resource availability. The effectiveness of the proposed scheduler is compared to those of a non-fuzzy scheduler as well as to those of a fuzzy scheduler which considers only uncertainties of application demands. Results evince the advantages of adopting the proposed scheduler.

• IC-12-04 pdf bib
  Scheduling Grid Tasks under Uncertain Demands.
  Daniel M. Batista, André C. Drummond, and Nelson L. S. da Fonseca.
  December 2011. In English, 11 pages.
  Abstract: The uncertainty of the demands of grid applications can cause unpredicted performance and, consequently, can make ineffective schedules derived for target demand values. To produce effective results, schedulers need to take into account the difficulty in estimating the demands of applications. In this paper, a scheduler based on fuzzy optimization is proposed to deal with such uncertainties. It is shown, via numerical results, that the proposed scheduler presents advantages when compared to classical schedulers.

• IC-12-03 pdf bib
  A Set of Schedulers for Grid Networks.
  Daniel M. Batista, Nelson L. S. da Fonseca, and Flavio K. Miyazawa.
  December 2011. In English, 11 pages.
  Abstract: Central to grid processing is the scheduling of application tasks to resources. Schedulers need to consider heterogeneous computational and communication resources, producing the shortest possible schedule under time constraints dictated by both the application needs and the frequency of fluctuation of resource availability. This paper introduces a set of schedulers with such characteristics.

• IC-12-02 pdf bib
  Self-Adjusting Grid Networks.
  Daniel M. Batista, Nelson L. S. da Fonseca, Fabrizio Granelli, and Dzmitry Kliazovich.
  December 2011. In English, 14 pages.
  Abstract: This paper introduces a procedure called Traffic Engineering for grids for enabling grid networks to self-adjust to resource availability. The proposal is based on monitoring the state of resources and on task migration. It involves several layers of the Internet architecture. Experiments executed in NS-2 are used to illustrate the efficacy of the procedure proposed.

• IC-12-01 pdf bib
  A Survey of Self-Adaptive Grids.
  Daniel M. Batista and Nelson L. S. da Fonseca.
  December 2011. In English, 13 pages.
  Abstract: Grid systems allow the execution of a class of highly demanding services and applications. These grids involve communication networks, and their links are essential resources for massive data transfers. However, the management of current grid systems requires intervention for efficient service provisioning. Moreover, this need increases with the increase in demand for grid services. Therefore, grid systems will become effective only when they are capable of self-managing resource allocation to cope with fluctuations in resource availability. At present, however, very few integrated self-adaptive mechanisms have been implemented in existing grid systems. The aim of this paper is to provide a survey of existing mechanisms and suggest directions for enabling autonomic operation of grid systems.