Didier Colle

Bio: Didier Colle is an academic researcher from Ghent University. The author has contributed to research in topics: Multiprotocol Label Switching & Network topology. The author has an hindex of 40, co-authored 508 publications receiving 8049 citations. Previous affiliations of Didier Colle include Intec, Inc. & Information Technology University.

Worldwide Energy Needs for leT: the Rise ofPower-Aware Networking

Abstract: As Information and Communication Technology (lCT) is becoming more and more wide-spread and pervasive in our daily life, it is important to get a realistic overview of the worldwide impact of ICT on the environment in general and on energy and electricity needs in particular. This paper reports on a detailed study to estimate this impact today and to predict how this will evolve in the future. From this survey important conclusions for the future of ICT industry and the internet will be drawn, and challenges and research directives will be deduced. ICT has a rather environmentally friendly image to the public community. This is largely correct: the worldwide communication via datacom and telecom networks has transformed society drastically and has opened opportunities to reduce the human impact on nature. Some typical examples are the rise of e-commerce, tele-working, tele- and video­ conferencing, reducing the worldwide traveling of both people and goods and hence the consumption of petroleum and the emission ofgreenhouse gases. A quite different example is the use of environmental sensors. Through wireless sensor network technology, different parameters like temperature, sun light and humidity can be measured and exploited to optimize the energy management in buildings. This ICT revolution has only just begun, and will have an ever stronger impact in the years to come. However, some dark clouds are looming at the horizon. The high penetration of ICT in our daily lives has as a drawback that the energy consumption of computers and network equipment is becoming a significant portion of the energy consumption worldwide and this portion is expected to grow steeply over the coming years. This energy consumption contains many obvious and less obvious facets. Of course electricity consumption of the ICT equipment during the operational lifetime is important. But also the complete manufacturing process to produce ICT equipment (with in many cases limited economical lifetimes) and the disposal process afterwards are having a large impact.

Worldwide energy needs for ICT: The rise of power-aware networking

Abstract: As Information and Communication Technology (ICT) is becoming more and more wide-spread and pervasive in our daily life, it is important to get a realistic overview of the worldwide impact of ICT on the environment in general and on energy and electricity needs in particular. This paper reports on a detailed study to estimate this impact today and to predict how this will evolve in the future. From this survey, important conclusions for the future of ICT industry and the Internet will be drawn, and challenges and research directives will be deduced.

Power consumption modeling in optical multilayer networks

Abstract: The evaluation of and reduction in energy consumption of backbone telecommunication networks has been a popular subject of academic research for the last decade. A critical parameter in these studies is the power consumption of the individual network devices. It appears that across different studies, a wide range of power values for similar equipment is used. This is a result of the scattered and limited availability of power values for optical multilayer network equipment. We propose reference power consumption values for Internet protocol/multiprotocol label switching, Ethernet, optical transport networking and wavelength division multiplexing equipment. In addition we present a simplified analytical power consumption model that can be used for large networks where simulation is computationally expensive or unfeasible. For illustration and evaluation purpose, we apply both calculation approaches to a case study, which includes an optical bypass scenario. Our results show that the analytical model approximates the simulation result to over 90% or higher and that optical bypass potentially can save up to 50% of power over a non-bypass scenario.

Pan-European optical transport networks: An availability-based comparison

Abstract: The traffic to be carried by today's European backbone networks increases very rapidly. An important portion of this traffic consists of data traffic (mainly IP-related). In the future data traffic is expected to become the abundantly dominant traffic type, while voice traffic will only account for a very small portion of the total traffic volume. In this paper, some network topologies for such a pan-European fiber-optic backbone network are presented (more details can be found in [1]). These topologies are compared in terms of the efficiency of the network design both from a cost and capacity point of view and in terms of the availability of the connections routed over this network. In order to be able to assess the network topologies under realistic circumstances, the expected traffic demand is forecasted. This enables to make the comparison for the current traffic volume as well as for the traffic patterns of the future. As not all types of (data) traffic require the same degree of survivability and in order to leverage the total capacity cost of the network design, a distinction is made between different recovery options in the optical layer for the different traffic types considered.

Pattern Recognition and Machine Learning

Abstract: Probability Distributions.- Linear Models for Regression.- Linear Models for Classification.- Neural Networks.- Kernel Methods.- Sparse Kernel Machines.- Graphical Models.- Mixture Models and EM.- Approximate Inference.- Sampling Methods.- Continuous Latent Variables.- Sequential Data.- Combining Models.

Random graphs

Abstract: We will review some of the major results in random graphs and some of the more challenging open problems. We will cover algorithmic and structural questions. We will touch on newer models, including those related to the WWW.

Software-Defined Networking: A Comprehensive Survey

Abstract: The Internet has led to the creation of a digital society, where (almost) everything is connected and is accessible from anywhere. However, despite their widespread adoption, traditional IP networks are complex and very hard to manage. It is both difficult to configure the network according to predefined policies, and to reconfigure it to respond to faults, load, and changes. To make matters even more difficult, current networks are also vertically integrated: the control and data planes are bundled together. Software-defined networking (SDN) is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network. The separation of concerns, introduced between the definition of network policies, their implementation in switching hardware, and the forwarding of traffic, is key to the desired flexibility: by breaking the network control problem into tractable pieces, SDN makes it easier to create and introduce new abstractions in networking, simplifying network management and facilitating network evolution. In this paper, we present a comprehensive survey on SDN. We start by introducing the motivation for SDN, explain its main concepts and how it differs from traditional networking, its roots, and the standardization activities regarding this novel paradigm. Next, we present the key building blocks of an SDN infrastructure using a bottom-up, layered approach. We provide an in-depth analysis of the hardware infrastructure, southbound and northbound application programming interfaces (APIs), network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications. We also look at cross-layer problems such as debugging and troubleshooting. In an effort to anticipate the future evolution of this new paradigm, we discuss the main ongoing research efforts and challenges of SDN. In particular, we address the design of switches and control platforms—with a focus on aspects such as resiliency, scalability, performance, security, and dependability—as well as new opportunities for carrier transport networks and cloud providers. Last but not least, we analyze the position of SDN as a key enabler of a software-defined environment.