Journal of High Speed Networks - Volume 19, issue 1

Authors: Tafani, Daniele | Kantarci, Burak | Mouftah, Hussein T. | McArdle, Conor | Barry, Liam P.

Article Type: Research Article

Abstract: Over the past decade, the ever-increasing energy demands of IT infrastructures have posed significant challenges for the research community in terms of reducing their total power consumption and minimizing their environmental impact. Optical communication networks are envisioned to be promising candidates to help preventing this problem affecting the Internet backbone, as well as for distributed applications such as computational grids. In this paper, we propose an adaptive and distributed scheme for the establishment of energy-efficient lightpaths in computational grids. The grid is deployed over an optical circuit-switched backbone network, defining an optical grid network. Each node of the backbone network …maintains two different dynamic thresholds values and estimates the changes in network performance by evaluating the moving average of the total wavelength channel occupancy on all its input/output links. The nodes have the ability of reducing the energy consumption by entering into an Energy Saving Mode (ESM) on the basis of a comparison between their channel occupancy and the thresholds. Furthermore, we extend our framework by allowing the thresholds to be dynamically adapted depending on the network performance in terms of blocking probability. We show that the proposed method achieves considerable energy savings when compared to a normal energy-unaware operational mode and still allows to maintain an acceptable level of network performance in terms of blocking probability and end-to-end delay. Numerical results are obtained with a Java event-driven simulator of two different optical network topologies. Show more

Keywords: Optical grid network, computational grid, energy efficiency, optical lightpath, dynamic sleep mode

DOI: 10.3233/JHS-130457

Citation: Journal of High Speed Networks, vol. 19, no. 1, pp. 1-18, 2013

Authors: Musumeci, Francesco | Tornatore, Massimo | Lopez Vizcaino, Jorge | Ye, Yabin | Pattavina, Achille

Article Type: Research Article

Abstract: Recently, the need for energy-efficient and sustainable capacity growth has become stringent for telecommunication networks and great efforts have been produced to reduce their power consumption. Optical technologies based on Wavelength Division Multiplexing are well-recognized as a promising solution for greening the future Internet. One relevant approach to achieve such power savings consists in aggregating traffic flows in few network links, so that power can be saved by switching-off some unused network devices. However, the need to ensure network resiliency against link and/or node failures imposes that still the resources reserved to protect connections become available immediately after a failure …occurs. Therefore, a possible solution is to set some devices into low-power sleep-mode, so that they can be rapidly re-activated and provide fast connection recovery. In this paper we focus on the power-efficiency of protected IP-over-WDM networks and provide a comprehensive comparison of four different protection strategies, namely Shared-Link, Shared-Path, Dedicated-Link and Dedicated-Path Protection (SLP, SPP, DLP and DPP respectively) in a sleep-mode scenario. In the proposed design strategies we assume that low-power sleep-mode is enabled for devices used for protection. Mathematical models for a power-aware design with sleep-mode is proposed for the four protection strategies. We show that relevant power savings (up to about 60%) can be obtained for all the protection strategies by setting protection devices into sleep-mode. Show more

Keywords: IP-over-WDM networks, power-awareness, sleep-mode, shared, dedicated, link, path protection

DOI: 10.3233/JHS-130463

Citation: Journal of High Speed Networks, vol. 19, no. 1, pp. 19-32, 2013

Authors: Osman, Niemah I. | El-Gorashi, Taisir | Elmirghani, Jaafar M.H.

Article Type: Research Article

Abstract: Increasing popularity of media-rich Internet content and the associated growth in power consumption have highlighted the need for energy efficient content distribution schemes. This paper investigates the power savings introduced by caching content in IP over WDM networks. To carry out the study, we develop a MILP model to minimize the power consumption of cache-based services over an IP over WDM network by optimizing the cache sizes of the network nodes at different times of the day. A Constraint-Based Genetic Algorithm (CBGA) is developed to validate the optimum cache sizes obtained from the MILP model and a simulation based on …lightpath bypass validates the power consumption of routing traffic demands. We consider different popularity distributions including the Zipf, Pareto and Bimodal content popularity distributions to exemplify different types of IPTV services. Our results reveal that deploying the optimum variable cache sizes at the nodes reduces the overall network power consumption by up to 42%, 68% and 72% using Zipf, Pareto and Bimodal distributions for content popularity, respectively. We further study the impact of regular cache updates on power efficiency. The results show that removing the 10 most popular objects from caches increases the network power consumption by up to 20%. Show more

Keywords: Cache hit ratio, content popularity distribution, IP over WDM

DOI: 10.3233/JHS-120458

Citation: Journal of High Speed Networks, vol. 19, no. 1, pp. 33-53, 2013

Authors: Hui, Rongqing | Huang, Wanjun | Zhang, Yuanyuan | Hameed, Mahmood | Razo, Miguel | Tacca, Marco | Fumagalli, Andrea

Article Type: Research Article

Abstract: This paper describes a rate flexible network transport solution to achieve sub-wavelength circuit provisioning between edge node pairs. Sub-wavelength circuits are obtained by concatenating spectrally efficient digital subcarrier channels along the network path, with each subcarrier frequency carrying only a fraction of the wavelength bandwidth. By reserving one or more such subcarrier frequencies along a path connecting two edge nodes, a dedicated end-to-end sub-wavelength circuit is provisioned. At an intermediate node, incoming frequencies are switched to outgoing frequencies via a cross-bar electronic circuit switch or cross-connect. By performing digital subcarrier multiplexing (DSCM) using CMOS based advanced digital signal processing (DSP) …algorithms, spectral guard-bands between adjacent channels are not necessary, thus yielding good bandwidth efficiency when multiplexing multiple subcarrier channels onto the same wavelength. Compared to current TDM based transport network solutions, e.g., OTN/SONET/SDH, the described solution offers the unique advantage of implementing two key transport functionalities in the same DSP system, which is capable of (1) performing compensation of fiber transmission impairments in the electronic domain to ensure good signal integrity, and (2) multiplexing (demultiplexing) subcarrier channels after (before) add/drop and switching circuit operations. Because of this design advantage, system complexity and fabrication of the network equipment are ameliorated, possibly leading to tangible cost and electric power consumption reductions. Show more

Keywords: Energy efficient transport network, circuit switched network, digital subcarrier multiplexing, digital subcarrier cross-connect, optical flow, UltraFlow

DOI: 10.3233/JHS-130465

Citation: Journal of High Speed Networks, vol. 19, no. 1, pp. 55-69, 2013

Authors: Testa, Patrizia | Germoni, Angelo | Listanti, Marco

Article Type: Research Article

Abstract: Telecommunication networks are evolving due to rapid growth of internet traffic and the necessity to satisfy the new requirements of emerging packet services. Upgrading of network devices so as they can allow scalable and full line rate traffic aggregation and eliminate any internal performance bottlenecks is crucial. In packet switching devices, since data plane functionalities need to be executed for each incoming packet and power per given bandwidth is strongly related to the amount of processing on this data, packet processing at ultra-high rate is becoming the major challenge. The main trend to address such power consumption and scalability issues …is to bypass packet switches by switching traffic at lower layers. This results in the packet optical transport network approach, where packet switching provides flexible end-to-end connectivity based on tunnel encapsulation while wavelength switching, exploiting optical bypass, allows reducing electrical switch size at transit nodes. There are also opportunities consisting in simplifying packet switch functionalities or designing completely different packet switch architectures. In this paper a new Ethernet aggregation and switching solution with potentialities to simplify and scale Ethernet switch forwarding functionality is proposed. This solution, based on a burst-basis transmission compliant with the Ethernet Standard, is able to maintain flexibility and any to any connectivity deriving from the connectionless nature of Ethernet. At the same time, it provides Ethernet technology with efficient aggregation capabilities allowing to reduce processing of transit traffic. This is allowed thanks to an Ethernet burst structure conceived as a variable number of consecutive frames of the same connection preceded by a proprietary burst control frame carrying information necessary for burst data frames classification. As a result, burst control frames experience the conventional Ethernet switch packet processing while data frames are mapped on the corresponding queue/output port according to the result of control frames classification. The proposed solution also provides the possibility to recognize data frames of the same burst through a proprietary inter-frame gap inserted among them; that allows to dynamically adapt burst size to the available bandwidth at transit nodes in order to limit frame delay and jitter and to support intermediate grooming. These features make it a very competitive approach in the context of packet optical transport being able to support dynamic multi-granular switching. The proposed solution has been validated by estimating its efficiency in terms of energy consumption with respect to a commercial packet switch. The impact of burst transmission on packet delay and jitter across ring and mesh networks has been also evaluated through different sets of simulations. Show more

Keywords: Packet switching, energy efficiency, Ethernet burst switching, traffic grooming

DOI: 10.3233/JHS-130464

Citation: Journal of High Speed Networks, vol. 19, no. 1, pp. 71-83, 2013

Authors: Aleksic, Slavisa | Fiorani, Matteo | Casoni, Maurizio

Article Type: Research Article

Abstract: Hybrid optical switching (HOS) has the potential to provide highly efficient operation through combining various switching paradigms and different implementation options within the same network. The flexibility of choosing between circuit, packet or burst switching and electronic or optical implementation results in an improvement of both energy and data transport efficiency because the most appropriate method and less power consuming elements can be selected and used for transmission of data through the network while temporarily inactive elements are switched off or put in a low-power mode. In this paper, we introduce a novel network concept that we refer to as …adaptive hybrid optical switching (AHOS) and present and investigate several architectures and realization options for AHOS nodes. The corresponding control plane comprises two layers, of which one implements routing, signalling and link management functions as defined in the GMPLS standard while the other is responsible for managing already established circuits and scheduling the transmission of packets and bursts. We present results on both performance and energy consumption for different AHOS node realizations, network configurations and traffic patterns, which prove the potential for a high improvement in energy efficiency with respect to conventional electronic packet-switched networks. Show more

Keywords: Energy efficiency, hybrid optical switching, performance evaluation

DOI: 10.3233/JHS-120456

Citation: Journal of High Speed Networks, vol. 19, no. 1, pp. 85-98, 2013