Bart Puype

Power consumption in telecommunication networks: overview and reduction strategies

One of the main challenges for the future of information and communication technologies is reduction of the power consumption in telecommunication networks. The key consumers are the home gateways at the customer premises for fixed line access technologies and the base stations for wireless access technologies. However, with increasing bit rates, the share of the core networks could become significant as well. In this article we characterize the power consumption in the different types of networks and discuss strategies to reduce the power consumption.

Design and implementation of the OFELIA FP7 facility: The European OpenFlow testbed

The growth of the Internet in terms of number of devices, the number of networks associated to each device and the mobility of devices and users makes the operation and management of the Internet network infrastructure a very complex challenge. In order to address this challenge, innovative solutions and ideas must be tested and evaluated in real network environments and not only based on simulations or laboratory setups. OFELIA is an European FP7 project and its main objective is to address the aforementioned challenge by building and operating a multi-layer, multi-technology and geographically distributed Future Internet testbed facility, where the network itself is precisely controlled and programmed by the experimenter using the emerging OpenFlow technology. This paper reports on the work done during the first half of the project, the lessons learned as well as the key advantages of the OFELIA facility for developing and testing new networking ideas. An overview on the challenges that have been faced on the design and implementation of the testbed facility is described, including the OFELIA Control Framework testbed management software. In addition, early operational experience of the facility since it was opened to the general public, providing five different testbeds or islands, is described.

Recovery in multilayer optical networks

The integration of different network technologies into a multilayer network, as in Internet-based networks carried by optical transport networks (OTNs), creates new opportunities but also challenges with respect to network survivability. In different network layers, recovery mechanisms that are active can be exploited jointly to reach a more efficient or faster recovery from failures. This interworking is also indispensable in order to overcome the variety of failure scenarios that can occur in the multilayer-network environment. A well-considered coordination between the different layers and their recovery mechanisms is crucial in order to attain high performance recovery. This paper provides an overview of multilayer recovery issues and solutions in an Internet protocol (IP)-over-optical-network environment, which is illustrated by quantitative case studies.

Power reduction techniques in multilayer traffic engineering

Automatically switched multilayer IP-over-optical networks offer extensive flexibility in coping with offered traffic. Multilayer traffic engineering (MLTE) takes advantage of this through online IP logical topology reconfiguration in addition to the more traditional rerouting. Although MLTE typically optimizes towards resource usage, bandwidth throughput and QoS performance, energy efficiency has become an equally important objective recently. In this paper, we examine two types of power reduction techniques and their interaction with the MLTE scheme: simple down-scaling of equipment power requirements, or more radical equipment architecture innovations which concentrate on reducing idle energy consumption. We show that both techniques require a different MLTE approach, and compare total power requirements for both scenarios.

Benefits of GMPLS for multilayer recovery

IP-based backbone networks are gradually moving towards a network model consisting of high-speed routers that are flexibly interconnected by lightpaths set up by an optical transport network consisting of WDM links and optical cross-connects. Recovery mechanisms at both network layers are crucial to reach the high availability requirements of critical services. In such a model, the GMPLS protocol suite can provide a distributed control plane that can be used to deliver rapid and dynamic circuit provisioning of end-to-end optical lightpaths. This article explains that it can be very beneficial to exploit this functionality to enhance the cost effectiveness of multilayer recovery significantly. Several practical case studies illustrate this concept and highlight the opportunities and challenges to be faced.

Optical networks: How much power do they consume and how can we optimize this?

Both bandwidth demand and energy consumption of ICT and communication networks is increasing and optical networks are regarded to provide high bandwidth solutions while enabling more energy efficiency. In this article we give an overview of energy consumption in access and core networks with a focus on optical technologies. Also, possible strategies to enable power reductions are discussed.

Multilayer traffic engineering for energy efficiency

Automatically switched multilayer IP-over-optical networks offer extensive flexibility in adapting the network to offered IP/MPLS traffic. Multilayer traffic engineering (MLTE) takes advantage of this through online IP logical topology reconfiguration in addition to the more traditional rerouting. The main goal of MLTE is to optimize toward resource usage, bandwidth throughput and QoS performance. However, energy efficiency of ICT infrastructure and the network in particular more recently have become an important aspect as well. In this article, we will look how MLTE helps in improving network energy efficiency. For this we will explain how optimization toward power requirement relates to the traditional resource usage minimization objective, and how power requirement in the network can be modeled for the MLTE algorithm. We will discuss two cases where the merit of MLTE for energy efficiency is discussed. Firstly, we will examine the interaction of MLTE with hardware-based energy efficiency optimization techniques; for this we look at scaling back power requirements through the use of better chip technology, but also decreasing idle-power requirement only, using improved chip architecture. Secondly, as MLTE allows for fast responses to changing traffic, we will see how link switch-off during off-peak hours offers a straightforward option to reduce energy needs.

Performance Evaluation of Multi-Layer Traffic Engineering Enabled IP-over-ION Networks

Recently, network operators started implementing traffic engineering (TE) techniques in their network. These TE techniques typically involve a single layer (for example, the IP/multi-protocol label switching (MPLS) layer). Although single-layer TE (STE) can improve the network performance (e.g., throughput, quality of service (QoS)), this improvement is bounded by the available capacity in that network layer. The evolution towards intelligent optical networks (IONs) allows further increasing the improvements achievable by the TE techniques, by involving more than one layer in the TE actions. Multi-layer TE (MTE) occupies network resources in a smart way and optimizes the QoS since it dynamically reconfigures the logical topology in the upper layer by properly updating the optical connections in the underlying optical layer. However, the performance of the network is impacted by the configuration scheme adopted by MTE. Therefore, in this paper, we focus on analyzing the influence of the MTE configuration scheme on the MTE behavior, and evaluate the network performance by studying simulation results obtained from a realistic IP-over-ION network.

Network Resilience in Future Optical Networks

Network resilience is an issue of deep concern to network operators being eager to deploy high-capacity fibre networks, since a single failure in the network could result in significant losses of revenue. The importance of network reliability will keep pace with the steadily increasing network capacity. For very-high-capacity future optical networks, carrying multitudes of 10 Gbit/s channels per fibre strand, a failure of optical connection will interrupt a vast amount of services running on-line, making the connection availability a factor of great significance. Therefore the ultrahigh capacity future optical networks will face a challenge of providing very efficient and fast survivability mechanisms. In this chapter we review the terminology and basic resilience techniques along with the results of research work on optical network survivability performed in the frame of COST291 cooperation. Our research work was focused on reliability performance improvement and on recovery in multilayer optical networks.

Multilayer traffic engineering for multiservice environments

Multilayer traffic engineering (MLTE) serves to provide cross-layer online network optimization techniques to cope with rapid variations and short-term evolutions in traffic patterns. MLTE extends traffic engineering as it exists in IP/MPLS-based technology toward the multilayer IP/MPLS-over-optical transport network. In addition to the IP/MPLS traffic routing, MLTE exposes much larger adaptation flexibility by building on next-generation automatic switched optical transport networks. These offer fast setup and teardown of end-to-end multi-hop optical connections (lightpaths), which are offered to the IP/MPLS layer as dynamically provisioned capacity. This dynamic nature leads to an IP/MPLS logical topology that can be reconfigured on the fly, and IP/MPLS link capacity that can be up- or downgraded as client traffic demand varies. These MLTE techniques are generally used to increase perceived network performance in terms of throughput or QoS. As such, a MLTE-managed network offers a better than best-effort service. Many types of traditional and novel services are shifting toward IP/MPLS technology. Consequentially, MLTE algorithms and strategies should be conceived with the characteristics of such services in mind. We present a MLTE strategy that can be implemented in a robust and distributed way. This strategy is then taken as the starting point in a study which evaluates its suitability to such services. We show how the strategy can be adapted considering service performance metrics such as end-to-end delay, traffic loss, and routing stability, and how such service optimizations impact general MLTE objectives such as IP/MPLS logical topology mesh size reduction.