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Author: Adrián Asensio García
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The huge energy consumption of datacenters (DC) requires an elastic resource management, e.g. by turning servers off when they are not used or turning them on to satisfy increments in the demand. Thanks to virtualization, jobs (e.g., web applications) can be encapsulated in virtual machines (VM) mixed with other workloads and consolidate them in the most proper server according to their performance goals. Local resource managers in DCs can migrate VMs from one server to another looking for reducing energy consumption while ensuring the committed quality of experience (QoE). Additionally, cloud providers can create DC federations based on a geographically distributed infrastructure so they can manage appropriately green energy resources available in each DC, thus reducing energy expenditure. Scheduling algorithms can perform VM migration not only within a single DC but also transferring a huge amount of raw data from one DC to another to minimize operational costs while ensuring the QoE. Since traffic between DCs is generated by VM migration, the connectivity required between two DCs highly varies along the day, presenting dramatic differences in an hourly time scale. Therefore, using a flexgrid-based optical network to interconnect DCs is an option to be considered since that technology provides fine and multiple granularity. In flexgrid optical networks the available optical spectrum is divided into frequency slices of fixed spectrum width. Optical connections can be allocated into a variable number of these slices, and its capacity can be dynamically managed by allocating or releasing slices provided that the spectrum allocated to an optical connection remain contiguous. Network providers can facilitate the interconnection among federated DCs by allowing them to request connections' set up on demand with the desired bitrate, while tearing down those connections when they are not needed. With this aim, in the last years, huge standardization work has been done defining control plane architectures and protocols to automate connection provisioning. The Internet Engineering Task Force (IETF) is defining the Application-Based Network Operations (ABNO) architecture, which is based on standard components such as the active stateful Path Computation Element (PCE). This thesis is devoted to characterize, evaluate and analyze the problem providing optimal VM placement so as to minimize operational costs assuming that those costs are dominated by energy and communication costs. To this aim, analytical models to optimize energy consumption in DC federations are provided. Both cloud and core optical network control architectures are explored and new connectivity models for elastic operations are proposed. Mixed integer linear programming models as well as heuristic algorithms are developed and simulations are carried out. More specifically, the main objective has been attained by developing three goals covering different open issues. First we propose the Elastic Operations in Federated Datacenters for Performance and Cost Optimization (ELFADO) problem for scheduling workload and orchestrating federated DCs. A distributed and a centralized approach are studied. Second we propose architectures based on ABNO, using cross-stratum orchestration and carrier SDN, as well as elastic connectivity models supported: the dynamic elastic model and a transfer mode model respectively. Finally, we consider the centralized ELFADO and both the dynamic elastic and transfer mode connectivity models proposed and evaluate their performance.
Author: Adrián Asensio García
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The huge energy consumption of datacenters (DC) requires an elastic resource management, e.g. by turning servers off when they are not used or turning them on to satisfy increments in the demand. Thanks to virtualization, jobs (e.g., web applications) can be encapsulated in virtual machines (VM) mixed with other workloads and consolidate them in the most proper server according to their performance goals. Local resource managers in DCs can migrate VMs from one server to another looking for reducing energy consumption while ensuring the committed quality of experience (QoE). Additionally, cloud providers can create DC federations based on a geographically distributed infrastructure so they can manage appropriately green energy resources available in each DC, thus reducing energy expenditure. Scheduling algorithms can perform VM migration not only within a single DC but also transferring a huge amount of raw data from one DC to another to minimize operational costs while ensuring the QoE. Since traffic between DCs is generated by VM migration, the connectivity required between two DCs highly varies along the day, presenting dramatic differences in an hourly time scale. Therefore, using a flexgrid-based optical network to interconnect DCs is an option to be considered since that technology provides fine and multiple granularity. In flexgrid optical networks the available optical spectrum is divided into frequency slices of fixed spectrum width. Optical connections can be allocated into a variable number of these slices, and its capacity can be dynamically managed by allocating or releasing slices provided that the spectrum allocated to an optical connection remain contiguous. Network providers can facilitate the interconnection among federated DCs by allowing them to request connections' set up on demand with the desired bitrate, while tearing down those connections when they are not needed. With this aim, in the last years, huge standardization work has been done defining control plane architectures and protocols to automate connection provisioning. The Internet Engineering Task Force (IETF) is defining the Application-Based Network Operations (ABNO) architecture, which is based on standard components such as the active stateful Path Computation Element (PCE). This thesis is devoted to characterize, evaluate and analyze the problem providing optimal VM placement so as to minimize operational costs assuming that those costs are dominated by energy and communication costs. To this aim, analytical models to optimize energy consumption in DC federations are provided. Both cloud and core optical network control architectures are explored and new connectivity models for elastic operations are proposed. Mixed integer linear programming models as well as heuristic algorithms are developed and simulations are carried out. More specifically, the main objective has been attained by developing three goals covering different open issues. First we propose the Elastic Operations in Federated Datacenters for Performance and Cost Optimization (ELFADO) problem for scheduling workload and orchestrating federated DCs. A distributed and a centralized approach are studied. Second we propose architectures based on ABNO, using cross-stratum orchestration and carrier SDN, as well as elastic connectivity models supported: the dynamic elastic model and a transfer mode model respectively. Finally, we consider the centralized ELFADO and both the dynamic elastic and transfer mode connectivity models proposed and evaluate their performance.
Author: Luis Velasco
Publisher: John Wiley & Sons
ISBN: 1119340411
Category : Science
Languages : en
Pages : 452
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Book Description
Explains the importance of Elastic Optical Networks (EONs) and how they can be implemented by the world’s carriers This book discusses Elastic Optical Networks (EONs) from an operational perspective. It presents algorithms that are suitable for real-time operation and includes experimental results to further demonstrate the feasibility of the approaches discussed. It covers practical issues such as provisioning, protection, and defragmentation. It also presents provisioning and recovery in single layer elastic optical networks (EON). The authors review algorithms for provisioning point-to-point, anycast, and multicast connections, as well as transfer-based connections for datacenter interconnection. They also include algorithms for recovery connections from failures in the optical layer and in-operation planning algorithms for EONs. Provisioning, Recovery and In-operation Planning in Elastic Optical Network also examines multi-layer scenarios. It covers virtual network topology reconfiguration and multi-layer recovery, and includes provisioning customer virtual networks and the use of data analytics in order to bring cognition to the network. In addition, the book: Presents managing connections dynamically—and the flexibility to adapt the connection bitrate to the traffic needs fit well for new types of services, such as datacenter interconnection and Network Function Virtualization (NFV) Examines the topic in a holistic and comprehensive way, addressing control and management plane issues for provisioning, recovery, and in-operation planning Covers provisioning, recovery, and in-operation planning for EONs at the proposed exhaustive level The rapid expanse of new services has made the use of EONs (a relatively new concept) a necessity. That’s why this book is perfect for students and researchers in the field of technologies for optical networks (specifically EONs), including network architectures and planning, dynamic connection provisioning, on-line network re-optimization, and control and management planes. It is also an important text for engineers and practitioners working for telecom network operators, service providers, and vendors that require knowledge on a rapidly evolving topic.
Author: Lluís Gifre Renom
Publisher:
ISBN:
Category :
Languages : en
Pages : 198
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Book Description
New generation applications, such as cloud computing or video distribution, can run in a telecom cloud infrastructure where the datacenters (DCs) of telecom operators are integrated in their networks thus, increasing connections' dynamicity and resulting in time-varying traffic capacities, which might also entail changes in the traffic direction along the day. As a result, a flexible optical technology able to dynamically set-up variable-capacity connections, such as flexgrid, is needed. Nonetheless, network dynamicity might entail network performance degradation thus, requiring re-optimizing the network while it is in operation. This thesis is devoted to devise new algorithms to solve in-operation network planning problems aiming at enhancing the performance of optical networks and at studying their feasibility in experimental environments. In-operation network planning requires from an architecture enabling the deployment of algorithms that must be solved in stringent times. That architecture can be based on a Path Computation Element (PCE) or a Software Defined Networks controller. In this thesis, we assume the former split in a front-end PCE, in charge of provisioning paths and handling network events, and a specialized planning tool in the form of a back-end PCE responsible for solving in-operation planning problems. After the architecture to support in-operation planning is assessed, we focus on studying the following applications: 1) Spectrum fragmentation is one of the most important problems in optical networks. To alleviate it to some extent without traffic disruption, we propose a hitless spectrum defragmentation strategy. 2) Each connection affected by a failure can be recovered using multiple paths to increase traffic restorability at the cost of poor resource utilization. We propose re-optimizing the network after repairing the failure to aggregate and reroute those connections to release spectral resources. 3) We study two approaches to provide multicast services: establishing a point-to-multipoint connections at the optical layer and using multi-purpose virtual network topologies (VNT) to serve both unicast and multicast connectivity requests. 4) The telecom cloud infrastructure, enables placing contents closer to the users. Based on it, we propose a hierarchical content distribution architecture where VNTs permanently interconnect core DCs and metro DCs periodically synchronize contents to the core DCs. 5) When the capacity of the optical backbone network becomes exhausted, we propose using a planning tool with access to inventory and operation databases to periodically decide the equipment and connectivity to be installed at the minimum cost reducing capacity overprovisioning. 6) In multi-domain multi-operator scenarios, a broker on top of the optical domains can provision multi-domain connections. We propose performing intra-domain spectrum defragmentation when no contiguous spectrum can be found for a new connection request. 7) Packet nodes belonging to a VNT can collect and send incoming traffic monitoring data to a big data repository. We propose using the collected data to predict next period traffic and to adapt the VNT to future conditions. The methodology followed in this thesis consists in proposing a problem statement and/or a mathematical formulation for the problems identified and then, devising algorithms for solving them. Those algorithms are simulated and then, they are experimentally assessed in real test-beds. This thesis demonstrates the feasibility of performing in-operation planning in optical networks, shows that it enhances the performance of the network and validates the feasibility of its deployment in real networks. It shall be mentioned that part of the work reported in this thesis has been done within the framework of several research projects, namely IDEALIST (FP7-ICT-2011-8) and GEANT (238875) funded by the EC and SYNERGY (TEC2014-59995-R) funded by the MINECO.
Author: Christoforos Kachris
Publisher: Springer Science & Business Media
ISBN: 1461446309
Category : Technology & Engineering
Languages : en
Pages : 179
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Book Description
Optical Interconnects in Future Data Center Networks covers optical networks and how they can be used to provide high bandwidth, energy efficient interconnects for future data centers with increased communication bandwidth requirements. This contributed volume presents an integrated view of the future requirements of the data centers and serves as a reference work for some of the most advanced solutions that have been proposed by major universities and companies. Collecting the most recent and innovative optical interconnects for data center networks that have been presented in the research community by universities and industries, this book is a valuable reference to researchers, students, professors and engineers interested in the domain of high performance interconnects and data center networks. Additionally, Optical Interconnects in Future Data Center Networks provides invaluable insights into the benefits and advantages of optical interconnects and how they can be a promising alternative for future data center networks.
Author: Víctor López
Publisher: Springer
ISBN: 3319301748
Category : Technology & Engineering
Languages : en
Pages : 301
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Book Description
This book presents advances in the field of optical networks - specifically on research and applications in elastic optical networks (EON). The material reflects the authors’ extensive research and industrial activities and includes contributions from preeminent researchers and practitioners in optical networking. The authors discuss the new research and applications that address the issue of increased bandwidth demand due to disruptive, high bandwidth applications, e.g., video and cloud applications. The book also discusses issues with traffic not only increasing but becoming much more dynamic, both in time and direction, and posits immediate, medium, and long-term solutions throughout the text. The book is intended to provide a reference for network architecture and planning, communication systems, and control and management approaches that are expected to steer the evolution of EONs.
Author: Frank Chang
Publisher: CRC Press
ISBN: 1000794938
Category : Computers
Languages : en
Pages : 758
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Book Description
In recent years, investments by cloud companies in mega data centers and associated network infrastructure has created a very active and dynamic segment in the optical components and modules market. Optical interconnect technologies at high speed play a critical role for the growth of mega data centers, which flood the networks with unprecedented amount of data traffic. Datacenter Connectivity Technologies: Principles and Practice provides a comprehensive and in-depth look at the development of various optical connectivity technologies which are making an impact on the building of data centers. The technologies span from short range connectivity, as low as 100 meters with multi-mode fiber (MMF) links inside data centers, to long distances of hundreds of kilometers with single-mode fiber (SMF) links between data centers.This book is the first of its kind to address various advanced technologies connecting data centers. It represents a collection of achievements and the latest developments from well-known industry experts and academic researchers active in this field.
Author: Francesco Testa
Publisher: Springer
ISBN: 331961052X
Category : Technology & Engineering
Languages : en
Pages : 334
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Book Description
This book introduces the reader to the optical switching technology for its application to data centers. In addition, it takes a picture of the status of the technology and system architecture evolution and of the research in the area of optical switching in data center. The book is organized in four parts: the first part is focused on the system aspects of optical switching in intra-data center networking, the second part is dedicated to describing the recently demonstrated optical switching networks, the third part deals with the latest technologies developed to enable optical switching and, finally, the fourth part of the book outlines the future prospects and trends.
Author: Darli Augusto de Arruda Mello
Publisher: Springer Nature
ISBN: 3030665410
Category : Technology & Engineering
Languages : en
Pages : 238
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Book Description
This textbook details the architecture of a digital coherent optical system and describes its main digital signal processing (DSP) algorithms. The authors first show how the combination of advanced modulation techniques, DSP and coherent detection has led to significant gains in capacity and ease of operation. The authors follow the path of the information from its generation in the transmitter, to propagation through the fiber and processing by the DSP algorithms in the receiver. The work summarizes academic results and presents them in a didactic way to students and practitioners working on the area of optical communications. A full suite of classroom materials is included for easy integration into a curriculum, containing theoretic and simulation problems, and off-the-shelf Matlab/Octave functions.
Author: Lin Wang
Publisher:
ISBN: 9781085581660
Category :
Languages : en
Pages :
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Book Description
Recently, IEEE 802.3 Ethernet Working Group has proposed a wavelength-agile (WA) PON as a promising candidate for Next-Generation Ethernet passive optical network (NG-EPON). We develop a mathematical model and a novel dynamic bandwidth and wavelength allocation (DBWA) scheme for transmission scheduling in WA-PON. Also, as WA-PON incurs penalties in terms of delay and power consumption when an ONU activates its transmissions on new wavelengths, a trade-off between energy saving and data-transfer latency reduction needs to be carefully addressed when performing transmission scheduling. So, we develop a power-consumption model and modify the proposed DBWA scheme to enhance the energy efficiency of WA-PON. Besides access network, optical networking plays an important role in intra-datacenter networks. We present a Packet-Switched Optical Network (PSON) architecture with centralized control for intra-datacenter connectivity. For efficient PSON operation, intelligent yet low-complexity bandwidth-scheduling algorithms are critical. To classify traffic flows with different characteristics, we investigate various machine learning (classification) techniques, and compare their performance in terms of accuracy and classification speed. We also develop a priority-aware scheduling algorithm for packet switching, which is optimized for PSON, and is adaptive to flow classification under dynamic traffic scenario. Inter-datacenter optical networking techniques, such as flex-grid switching, have been recognized as the solution for backbone networks. However, they may fall short in efficiently provisioning traffic requests for intra-datacenter networks. We investigate an Optical Time Slice Switching (OTSS) enabled flex-grid (OTSS-FG) architecture for intra-datacenter networks. For scenarios where traffic flows are given, we develop a Mixed Integer Linear Program to study the optimal bandwidth allocation scheme in an OTSS-FG architecture. When traffic flows are generated in real time, by leveraging machine-learning techniques to detect flow types, we propose a flow-aware bandwidth allocation (FABA) scheme and a dynamic version of FABA, called “D-FABA” scheme. Then, we study traffic flows for intra-datacenter networks. Coflow is a networking abstraction to convey application-level communication requirements by exposing rich semantics of data-parallel computing applications to underlying networks, e.g., latency of data transmission between two computation stages, known as “Coflow Completion Time” (CCT). We study how to minimize CCT in PSON-enabled datacenters by placing senders and receivers of Coflows to proper transceiver nodes and scheduling data transmission wisely, for which we propose a Coflow-aware placement and scheduling algorithm, consisting of Min-Priority placement algorithm and Priority-aware scheduling algorithm. They are designed to cooperate with each other to jointly minimize CCT. Finally, we conclude four works and discuss open problem of OTSS-enabled Flex-grid network architecture.
Author: Alberto Castro
Publisher:
ISBN:
Category :
Languages : en
Pages : 219
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Book Description
The ever increasing IP traffic volume has finally brought to light the high inefficiency of current wavelength-routed over rigid-grid optical networks in matching the client layer requirements. Such an issue results in the deployment of large-size, expensive and power-consuming Multiprotocol Label Switching (MPLS) layers to perform the required grooming/aggregation functionality. To deal with this problem, the emerging flexgrid technology, allowing for reduced size frequency grids, is being standardized. Flexgrid optical networks divide the spectrum into frequency slots providing finer granularity than rigid networks based on Dense Wavelength Division Multiplexing (DWDM). To find a feasible allocation, new Routing and Spectrum Allocation (RSA) algorithms for flexgrid optical networks need to be designed and evaluated. Furthermore, due to the flexibility of flexible optical networks, the aggregation functions and statistical multiplexing can be partially located in the optical layer. In addition, given the special characteristics of flexible optical networks, the traditional mechanisms for protection and recovery must be reformulated. Optical transport platforms are designed to facilitate the setting up and tearing down of optical connections (lightpaths). Combining remotely configurable optical cross-connects (OXCs) with a control plane provides the capability of automated lightpath set-up for regular provisioning, and real-time reaction to the failures, being thus able to reduce Operational Expenditures (OPEX). However, to exploit existing capacity, increase dynamicity, and provide automation in future networks, current management architectures, utilizing legacy Network Management Systems (NMS) need to be radically transformed. This thesis is devoted to design optical networks and to devise algorithms to operate them. Network design objective consists of: i.Analyzing the cost implications that a set of frequency slot widths have on the Capital Expenditures (CAPEX) investments required to deploy MPLS-over-flexgrid networks; ii.Studying recovery schemes, where a new recovery scheme specifically designed for flexgrid-based optical networks is proposed. As for network operation, we focus on: i.Studying provisioning, where two provisioning algorithms are proposed: the first one targets at solving the RSA problem in flexgrid networks, whereas the second one studies provisioning considering optical impairments in translucent DWDM networks; ii.Getting back to the recovery problem, we focus on algorithms to cope with restoration in dynamic scenarios. Several algorithms are proposed for both single layer and multilayer networks to be deployed in the centralized Path Computation Element (PCE); iii.One of the main problems in flexgrid networks is spectrum defragmentation. In view of that, we propose an algorithm to reallocate already established optical connections so as to make room for incoming requests. This algorithm is extended with elasticity to deal with time-varying traffic. The above algorithms are firstly implemented and validated by using simulation, and finally experimentally assessed in real test-beds. In view of PCE architectures do not facilitate network reconfiguration, we propose a control and management architecture to allow the network to be dynamically operated; network resources can be made available by reconfiguring and/or re-optimizing the network on demand and in real-time. We call that as in-operation network planning. It shall be mentioned that part of the work reported in this thesis has been done within the framework of several European and National projects, namely STRONGEST (FP7-247674), IDEALIST (FP7-ICT-2011-8), and GEANT (FP7-238875) funded by the European Commission, and ENGINE (TEC2008-02634) and ELASTIC (TEC2011-27310) funded by the Spanish Science Ministry.
