Revisiting core traffic growth in the presence of expanding CDNs

Traffic growth forecasts announce a dramatic future for core networks, struggling to keep the pace of traffic augmentation. Internet traffic growth primarily stems from the proliferation of cloud services and the massive amounts of data distributed by the content delivery networks (CDNs) hosting these services. In this paper, we investigate the evolution of core traffic in the presence of growing CDNs. Expanding the capacities of existing data centers (DCs) directly translates the forecasted compound-annual-growth-rate (CAGR) of user traffic to the CAGR of carried core link traffic. On the other hand, expanding CDNs by building new geographically dispersed DCs can significantly reduce the predicted core traffic growth rates by placing content closer to the users. However, reducing DC-to-user traffic by building new DCs comes at a trade-off with increasing inter-DC content synchronization traffic. Thus, the resulting overall core traffic growth will depend on the types of services supported and their associated synchronization requirements. In this paper, we present a long-term evolution study to assess the implications of different CDN expansion strategies on core network traffic growth considering a mix of services in proportions and growth rates corresponding to well-known traffic forecasts. Our simulations indicate that CDNs may have significant incentive to build more DCs, depending on the service types they offer, and that current alarming traffic predictions may be somewhat overestimated in core networks in the presence of expanding CDNs. (C) 2019 The Authors. Published by Elsevier B.V.The research leading to these results has received funding from the European Commission for the H2020-ICT-2016-2 METRO-HAUL project (G.A. 761727) and it has been partially funded by the Spanish national project ONOFRE-2(TEC2017-84423-C3-1-P, MINECO/AEI/FEDER, UE)

Planificación y optimización de redes ópticas en el Internet del futuro

[SPA] Las estrictas exigencias requeridas por la futura red 5G, junto a las elevadas previsiones de crecimiento de tráfico IP, principalmente cimentadas en la proliferación de numerosos servicios basados en la nube, crean un panorama futuro lleno de incógnitas desde la perspectiva de las grandes redes ópticas de telecomunicaciones. Las tareas de planificación y optimización serán esenciales para asegurar que los requisitos pueden cumplirse de una manera económicamente viable. Esta tesis trata de analizar, en primer lugar, la validez de las predicciones de crecimiento tráfico, a la luz de las actuales aplicaciones y en un escenario donde los requisitos de latencia implican la evolución de los CDNs con el despliegue de micro-datacenters. Se analizará en particular el efecto de esta evolución en el tráfico soportado por las redes ópticas troncales. Segundo, la tesis estudia opciones que permitan abordar los requisitos esperados de la red, desde tres enfoques: a) optimización en el diseño y gestión de CDNs, b) control programable de la red basado, en redes definidas por software (SDN) y con virtualización en las funciones de red (NFV) y por último, c) posible introducción de tecnología SDM (Space Division Multiplexing) para expandir la capacidad de las redes de transporte como soporte efectivo del incremento de tráfico IP. Los resultados de este trabajo concluyen, en primera instancia, que la evolución del tráfico troncal en el Internet del futuro dependerá de la naturaleza de los servicios que las aplicaciones ofrezca, siendo el balance entre el tráfico de usuario y de sincronización especialmente determinante. Por otro lado, los resultados sugieren que un acercamiento del contenido a los usuarios puede tener el efecto neto de disminuir la cantidad de tráfico soportada por las redes core, en relación con las previsiones actuales. Los casos de uso analizados en el entorno SDN-NFV determinan la necesidad de optimización para proporcionar flexibilidad y programabilidad en la migración hacia sistemas virtualizados en las redes, siendo este conjunto de funcionalidades esenciales para satisfacer los requerimientos de los futuros servicios en el paradigma 5G. Además, las pruebas de concepto presentadas avalan la optimización conjunta de recursos de red e IT para la asistencia de service chains en redes basadas en SDN-NFV. Finalmente, para las redes ópticas basadas en SDM, la propuesta presentada de restricción de canal espacial (SCC) emerge como una opción válida a implementar en ROADMs para contextos flex-grid. La validez de tal propuesta reside en la reducción de coste de implementación dada por su menor complejidad y mayor disponibilidad de equipamiento, a costa de mínimas pérdidas en rendimiento, respecto de opciones totalmente permisivas.[ENG] The strict requirements required for the future 5G network, jointly with the high growth forecasts of IP traffic, mainly based on the proliferation of cloud services, create a future panorama full of uncertainties from the perspective of large optical telecommunications networks. Planning and optimization tasks are essential to ensure that the requirements are satisfied in an economically viable manner. This thesis tries to analyze, in the first place, the validity of traffic growth predictions, in the light of current applications in a scenario where the latency requirements imply the evolution of CDNs with the deployment of micro-datacenters. In particular, the effect of this traffic evolution, supported by the optical backbone networks, will be analyzed. Second, the thesis studies some options that allow addressing the expected requirements of the network, from the perspective of three major approaches: a) optimization in the design and management of CDNs, b) programmable control of the network based on software-defined networking and with virtualization in network functions and finally, c) possible introduction of the Space Division Multiplexing (SDM) technology to expand the capacity of transport networks as effective support for the increase of IP traffic. The outcomes of this work conclude, in the first instance, that the evolution of the backbone traffic in the future Internet will depend on the nature of the services that the applications offer, being the balance between user traffic and synchronization one especially determining. On the other hand, the results suggest that place the content close to the users can have direct effect of decreasing the amount of traffic supported by the core networks, in relation to the current forecasts. The use cases analyzed in the SDN-NFV environment determine the need for optimization providing flexibility and programmability in the migration to virtualized systems in the networks. This set of functionalities are essential to satisfy the requirements of the future services in the 5G paradigm. In addition, the proof of concept presented in this thesis supports the joint optimization of network and IT resources for the assistance of service chains in networks based on SDN-NFV. Finally, for SDM-based optical networks, the proposal presented for space channel restriction (SCC) emerges as a valid option to be implemented in ROADMs for flex-grid environments. The validity of this proposal lies in the significant reduction in terms of implementation cost due to its lower complexity and the current availability of the equipment, at the expense of minimal performance degradations, compared to totally permissive options.Escuela Internacional de Doctorado de la Universidad Politécnica de CartagenaUniversidad Politécnica de CartagenaPrograma de Doctorado en Tecnologías de la Información y las Comunicaciones por la Universidad Politécnica de Cartagen

Energy Efficient Big Data Networks

The continuous increase of big data applications in number and types creates new challenges that should be tackled by the green ICT community. Data scientists classify big data into four main categories (4Vs): Volume (with direct implications on power needs), Velocity (with impact on delay requirements), Variety (with varying CPU requirements and reduction ratios after processing) and Veracity (with cleansing and backup constraints). Each V poses many challenges that confront the energy efficiency of the underlying networks carrying big data traffic. In this work, we investigated the impact of the big data 4Vs on energy efficient bypass IP over WDM networks. The investigation is carried out by developing Mixed Integer Linear Programming (MILP) models that encapsulate the distinctive features of each V. In our analyses, the big data network is greened by progressively processing big data raw traffic at strategic locations, dubbed as processing nodes (PNs), built in the network along the path from big data sources to the data centres. At each PN, raw data is processed and lower rate useful information is extracted progressively, eventually reducing the network power consumption. For each V, we conducted an in-depth analysis and evaluated the network power saving that can be achieved by the energy efficient big data network compared to the classical approach. Along the volume dimension of big data, the work dealt with optimally handling and processing an enormous amount of big data Chunks and extracting the corresponding knowledge carried by those Chunks, transmitting knowledge instead of data, thus reducing the data volume and saving power. Variety means that there are different types of big data such as CPU intensive, memory intensive, Input/output (IO) intensive, CPU-Memory intensive, CPU/IO intensive, and memory-IO intensive applications. Each type requires a different amount of processing, memory, storage, and networking resources. The processing of different varieties of big data was optimised with the goal of minimising power consumption. In the velocity dimension, we classified the processing velocity of big data into two modes: expedited-data processing mode and relaxed-data processing mode. Expedited-data demanded higher amount of computational resources to reduce the execution time compared to the relaxed-data. The big data processing and transmission were optimised given the velocity dimension to reduce power consumption. Veracity specifies trustworthiness, data protection, data backup, and data cleansing constraints. We considered the implementation of data cleansing and backup operations prior to big data processing so that big data is cleansed and readied for entering big data analytics stage. The analysis was carried out through dedicated scenarios considering the influence of each V’s characteristic parameters. For the set of network parameters we considered, our results for network energy efficiency under the impact of volume, variety, velocity and veracity scenarios revealed that up to 52%, 47%, 60%, 58%, network power savings can be achieved by the energy efficient big data networks approach compared to the classical approach, respectively

Physical Layer Aware Optical Networks

This thesis describes novel contributions in the field of physical layer aware optical networks. IP traffic increase and revenue compression in the Telecom industry is putting a lot of pressure on the optical community to develop novel solutions that must both increase total capacity while being cost effective. This requirement is pushing operators towards network disaggregation, where optical network infrastructure is built by mix and match different physical layer technologies from different vendors. In such a novel context, every equipment and transmission technique at the physical layer impacts the overall network behavior. Hence, methods giving quantitative evaluations of individual merit of physical layer equipment at network level are a firm request during network design phases as well as during network lifetime. Therefore, physical layer awareness in network design and operation is fundamental to fairly assess the potentialities, and exploit the capabilities of different technologies. From this perspective, propagation impairments modeling is essential. In this work propagation impairments in transparent optical networks are summarized, with a special focus on nonlinear effects. The Gaussian Noise model is reviewed, then extended for wideband scenarios. To do so, the impact of polarization mode dispersion on nonlinear interference (NLI) generation is assessed for the first time through simulation, showing its negligible impact on NLI generation. Thanks to this result, the Gaussian Noise model is generalized to assess the impact of space and frequency amplitude variations along the fiber, mainly due to stimulated Raman scattering, on NLI generation. The proposed Generalized GN (GGN) model is experimentally validated on a setup with commercial linecards, compared with other modeling options, and an example of application is shown. Then, network-level power optimization strategies are discussed, and the Locally Optimization Global Optimization (LOGO) approach reviewed. After that, a novel framework of analysis for optical networks that leverages detailed propagation impairment modeling called the Statistical Network Assessment Process (SNAP) is presented. SNAP is motivated by the need of having a general framework to assess the impact of different physical layer technologies on network performance, without relying on rigid optimization approaches, that are not well-suited for technology comparison. Several examples of applications of SNAP are given, including comparisons of transceivers, amplifiers and node technologies. SNAP is also used to highlight topological bottlenecks in progressively loaded network scenarios and to derive possible solutions for them. The final work presented in this thesis is related to the implementation of a vendor agnostic quality of transmission estimator for multi-vendor optical networks developed in the context of the Physical Simulation Environment group of the Telecom Infra Project. The implementation of a module based on the GN model is briefly described, then results of a multi-vendor experimental validation performed in collaboration with Microsoft are shown

A Survey of Software-Defined Networking: Past, Present, and Future of Programmable Networks

accepted in IEEE Communications Surveys & TutorialsInternational audienceThe idea of programmable networks has recently re-gained considerable momentum due to the emergence of the Software-Defined Networking (SDN) paradigm. SDN, often referred to as a ''radical new idea in networking'', promises to dramatically simplify network management and enable innovation through network programmability. This paper surveys the state-of-the-art in programmable networks with an emphasis on SDN. We provide a historic perspective of programmable networks from early ideas to recent developments. Then we present the SDN architecture and the OpenFlow standard in particular, discuss current alternatives for implementation and testing of SDN-based protocols and services, examine current and future SDN applications, and explore promising research directions based on the SDN paradigm

Models of vertical interconnection in the future internet networks

Interkonekcija, čiji primarni cilj je omogućavanje korisnicima jednog učesnika na tržištu telekomunikacija da komuniciraju sa korisnicima drugog učesnika, odnosno, obezbeđivanje pristupa servisima koje obezbeđuje drugi učesnik, javila se nakon liberalizacije tržišta telekomunikacija. Vertikalna interkonekcija predstavlja fizičko i logičko povezivanje učesnika na različitim nivoima mreže. U okruženju budućeg Interneta, sagledavanje tehničko-ekonomskih aspekata interkonekcije predstavlja pitanje od izuzetnog značaja. U opštem slučaju, učesnici u vertikalnoj interkonekciji u okruženju budućeg Interneta mogu biti provajderi sadržaja i aplikacija, provajderi Internet servisa, Content Delivery Network (CDN) provajderi i cloud provajderi. Pojava Cloud Computing-a uvela je značajne promene u Internet okruženju koje se pre svega odnose na mogućnost pristupa skalabilnim i deljivim, fizičkim ili virtuelnim resursima. Na taj način, stvara se elastična platforma koja obezbeđuje dinamičnu i jednostavnu skalabilnost, pojednostavljuje se obezbeđivanje infrastrukture i omogućava se unapređenje performansi. Razvoj servisa i aplikacija zahtevnih u pogledu propusnog opsega praćen širom implementacijom Cloud Computing-a utiče na kontinuiran rast Internet saobraćaja, što zahteva primenu tehnologija koje mogu zadovoljiti sve strože zahteve. Kao rešenje za transportni nivo mreže, razvijene su elastične optičke mreže koje mogu obezbediti dovoljne propusne opsege uz efikasno iskorišćenje spektra. Imajući u vidu promene koje prate razvoj okruženja budućeg Interneta, kao i značaj vertikalne interkonekcije, neophodno je razmotriti i jasno definisati tehničko-ekonomske relacije između učesnika u budućem Internetu, što je predmet istraživanja ove doktorske disertacije. U okviru disertacije predložen je model koji ima za cilj određivanje adekvatnog ugovora o interkonekciji između učesnika u vertikalnoj interkonekciji, i to provajdera sadržaja i aplikacija i provajdera Internet servisa u procesu obezbeđivanja sadržaja krajnjim korisnicima, uz mogućnost parcijalne migracije sadržaja na resurse cloud provajdera. Analiza obuhvata različite ugovore o interkonekciji i određuje adekvatan ugovor, u zavisnosti od ciljnih profita provajdera koji učestvuju u vertikalnoj interkonekciji i prihvatljive stope odbijenih zahteva za obezbeđivanje sadržaja krajnjim korisnicima. Data analiza je proširena istraživanjem adekvatnog mehanizma tarifiranja i alokacije resursa cloud provajdera. Predložen je nov, hibridni model pristupa resursima cloud provajdera koji obezbeđuje zadovoljavajuće rezultate u kontekstu minimizacije troškova i minimizacije stope odbijenih zahteva za pristup sadržajima...Interconnection, whose primary aim is enabling communication between end users of different undertakings, i.e. enabling access to the other undertaking's services, was introduced after the telecommunication market liberalization. Vertical interconnection represents the physical and logical linking of the undertakings on different network levels. Consideration of technical and economic aspects of the interconnection is a crucial issue in the future Internet environment. In general, undertakings in vertical interconnection in the future Internet environment include content and application providers, Internet service providers, Content Delivery Network (CDN) providers and Cloud providers. The development of Cloud Computing introduced significant changes in the Internet environment in terms of enabling access to scalable and shareable, physical or virtual resources. Therefore, the elastic platform for dynamic and simple scalability is enabled, the access to infrastructure is simplified and performances are improved. High bandwidth demanding services and applications, along with the wide adoption of Cloud Computing causes permanent growth of Internet traffic. This indicates that the introduction of new technologies, capable to satisfy high bandwidth requirements, is necessary. Elastic optical networks are proposed as a promising solution for transport networks. These networks provide enough bandwidth, along with high efficiency in spectrum utilization. Forasmuch changes in the future Internet environment and the importance of the vertical interconnection, it is mandatory to consider and properly define technical and economic relations between undertakings in the future Internet environment, which is the research subject of this doctoral dissertation. Within dissertation, a model for the determination of a proper interconnection agreement between undertakings in the vertical interconnection, content and application provider and an Internet service provider, in the content provisioning process with partial cloud migration is proposed. The analysis comprises different interconnection agreements and determines appropriate agreement, depending on the targeted providers' profits and satisfying requests' for content provisioning rejection rate. This analysis is extended to determine adequate pricing and allocation mechanism for cloud provider's resources. A new, hybrid model for enabling access to cloud resources is proposed. The model provides satisfying results in terms of the costs' minimization and the minimization of requests' rejection rate..

Joint content placement and lightpath routing and spectrum assignment in CDNs over elastic optical network scenarios

© 2015 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/In this work, we address the problem of jointly deciding the placement of the contents delivered by a Content Distribution Network (CDN) among the available data centers, together with the allocation of the lightpaths required to serve the anycast demands initiated by the CDN network users, assuming an underlying highcapacity Elastic Optical Network (EON). We firstly present an Integer Linear Programming (ILP) formulation to optimally solve the targeted problem. This ILP formulation is of high complexity, though, and cannot be used to solve realistically sized problem instances. Hence, we also introduce a novel heuristic called CPRMSAPD, which decomposes the problem into three sub-problems and applies greedy heuristics and simulated annealing meta-heuristic techniques to yield accurate solutions with practical execution times. We validate the performance of our CPRMSA-PD heuristic in medium-sized problem instances by comparing its results to the ones of the optimal ILP formulation. Next, we use it to give extensive insights into the effects of different key parameters identified in large CDN over EON backbone networks.Peer Reviewe

Joint content placement and lightpath routing and spectrum assignment in CDNs over elastic optical network scenarios

© 2015 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/In this work, we address the problem of jointly deciding the placement of the contents delivered by a Content Distribution Network (CDN) among the available data centers, together with the allocation of the lightpaths required to serve the anycast demands initiated by the CDN network users, assuming an underlying highcapacity Elastic Optical Network (EON). We firstly present an Integer Linear Programming (ILP) formulation to optimally solve the targeted problem. This ILP formulation is of high complexity, though, and cannot be used to solve realistically sized problem instances. Hence, we also introduce a novel heuristic called CPRMSAPD, which decomposes the problem into three sub-problems and applies greedy heuristics and simulated annealing meta-heuristic techniques to yield accurate solutions with practical execution times. We validate the performance of our CPRMSA-PD heuristic in medium-sized problem instances by comparing its results to the ones of the optimal ILP formulation. Next, we use it to give extensive insights into the effects of different key parameters identified in large CDN over EON backbone networks.Peer Reviewe