scholarly journals Disaster-Resilient Optical Network Survivability: A Comprehensive Survey

Photonics ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 35 ◽  
Author(s):  
Muhammad Ashraf ◽  
Sevia Idrus ◽  
Farabi Iqbal ◽  
Rizwan Butt ◽  
Muhammad Faheem
Keyword(s):  
Optical Networks ◽  
Fault Tolerant ◽  
Optical Network ◽  
Network Survivability ◽  
Cascading Failures ◽  
Data Traffic ◽  
News Reports ◽  
Comprehensive Survey ◽  
Network Failures ◽  
Component Failures

Network survivability endeavors to ensure the uninterrupted provisioning of services by the network operators in case of a disaster event. Studies and news reports show that network failures caused by physical attacks and natural disasters have significant impacts on the optical networks. Such network failures may lead to a section of a network to cease to function, resulting in non-availability of services and may increase the congestion within the rest of the network. Therefore, fault tolerant and disaster-resilient optical networks have grasped the attention of the research community and have been a critical concern in network studies during the last decade. Several studies on protection and restoration techniques have been conducted to address the network component failures. This study reviews related previous research studies to critically discuss the issues regarding protection, restoration, cascading failures, disaster-based failures, and congestion-aware routing. We have also focused on the problem of simultaneous cascading failures (which may disturb the data traffic within a layer or disrupt the services at upper layers) along with their mitigating techniques, and disaster-aware network survivability. Since traffic floods and network congestion are pertinent problems, they have therefore been discussed in a separate section. In the end, we have highlighted some open issues in the disaster-resilient network survivability for research challenges and discussed them along with their possible solutions.

SONET/SDH, OTN, and RPR

2021 ◽  
pp. 189-232
Author(s):  
Debasish Datta
Keyword(s):  
Optical Networks ◽  
Optical Fibers ◽  
High Speed ◽  
Optical Network ◽  
Data Traffic ◽  
Ring Networks ◽  
Synchronous Digital Hierarchy ◽  
Transmission Rates ◽  
Optical Transport Network ◽  
Basic Concepts

With the emergence of high-speed optical transmission, the pre-existing plesiochronous digital hierarchy (PDH) appeared unsuitable for achieving network synchronization, leading to the development of the synchronous optical network (SONET) and synchronous digital hierarchy (SDH) as the two equivalent standards for circuit-switched optical networks. Several bandwidth-efficient techniques were also developed to carry packet-switched data traffic over SONET/SDH networks, offering some useful data-over-SONET/SDH architectures. Subsequently, with the increasing transmission rates for SONET/SDH and Ethernet-based LANs, a convergent networking platform called optical transport network (OTN), was developed. With the ever-increasing volume of bursty data traffic, a standard for packet-switched ring networks, called resilient packet ring (RPR), was also developed for better bandwidth realization in optical fibers. In this chapter, we first present the SONET/SDH networks and the techniques for supporting the data traffic therein, followed by a description of the basic concepts and salient features of the OTN and RPR networks. (147 words)

Performance Improvement of WDM Optical Network using Optimal Regenerator Placement Strategy

2019 ◽  
Vol 41 (1) ◽  
pp. 83-89
Author(s):  
Karamjit Kaur ◽  
Anil Kumar ◽  
Hardeep Singh
Keyword(s):  
Optical Networks ◽  
Performance Improvement ◽  
System Performance ◽  
Optical Network ◽  
Signal Quality ◽  
Data Traffic ◽  
Optical Links ◽  
Signal Regeneration ◽  
Optimum Placement ◽  
Physical Layer Impairments

Abstract As the optical networks are moving towards transparent networks, the Optical-to-Electrical (O-E) conversion taking place within the link is reduced to minimal. This results into accumulation of physical layer impairments along the light path, thereby degrading the signal quality. Due to enormous data traffic carried by optical links, any link failure or non-recovery to data at the destination end may result in huge loss. To improve the system performance, the optimum placement of regenerators is one of the solutions for the same, where signal regeneration may takes place at certain pre-specified nodes. Three different strategies of regenerator placement are discussed in the present work. The improvement in system performance with this is also presented.

scholarly journals Redes ópticas elásticas: un nuevo paradigma en las futuras redes de telecomunicaciones

Respuestas ◽  
2015 ◽  
Vol 20 (2) ◽  
pp. 6 ◽  
Author(s):  
Jhon James Granada-Torres ◽  
Ana María Cárdenas-Soto ◽  
Neil Guerrero-González
Keyword(s):  
Optical Networks ◽  
Capacity Planning ◽  
Optical Network ◽  
High Capacity ◽  
Digital Signal ◽  
Spectral Width ◽  
Modulation Formats ◽  
Optical Transmission Systems ◽  
Comprehensive Survey ◽  
Increasing Demand

ResumenEl tráfico en las redes de datos por fibra óptica ha tenido un crecimiento exponencial debido a la creciente demanda de información por parte de los usuarios finales, llevando a una saturación en la capacidad de las redes actuales. Proyectando los sistemas de transmisiones ópticos a tasas superiores a los 400 Gbps para redes de largo alcance, no será posible mantener la tecnología WDM de rejilla espectral fija de 50 GHz, la cual permite transmitir en la actualidad tasas hasta los 100 Gbps. Teniendo como limitación además del ancho espectral que ocuparía la información, la conmutación de los dispositivos para trabajar a altas frecuencias. En este contexto, surge el concepto de las redes ópticas elásticas, donde se emplea una rejilla de espectro flexible (flexi-grid) o sin rejilla (grid-less), con ancho espectral variable por canal según la demanda de ancho de banda, permitiendo una separación espectral flexible entre canales con el propósito de optimizar la eficiencia en el uso del espectro. Este artículo hace una revisión de los nuevos conceptos tecnológicos que conllevan el escenario de redes elásticas, y los posibles retos y limitaciones para el desarrollo de estas tecnologías. Recientes pruebas experimentales incorporan nuevos conceptos tecnológicos con relación a los ya comerciales sistemas de 100-G como: el diseño de transmisores multicanales, el uso de tecnologías como Nyquist-WDM y OFDM óptico flexible, receptores digitales coherentes reconfigurables, formatos de modulación m-arios e híbridos y asignación dinámica del espectro. No obstante, grandes limitantes como los efectos no lineales de la fibra óptica deben ser foco de investigación en este nuevo escenario, debido a sus efectos en la degradación de la señal. Finalmente, se muestra como las técnicas de procesamiento digital de señales desempeñarán un papel importante para lograr la reconfigurabilidad y elasticidad de las redes de alta capacidad.AbstractIn the last years, traffic on data optical networks has had an exponential growth due to the increasing demand of information by end users. This had lead to saturation of the current deployed networks in terms of capacity. Planning the optical transmission systems of long-reach to work with capacities above 400 Gbps, it will not be possible to keep the spectral fixed-grid of the WDM technology, which currently allows transmitting up to 100 Gbps. The principal limitation is due to the greater spectral bandwidth occupied by the data information and also due to the switching of electronics devices at high frequencies. In this context a new concept known as elastic optical network emerges, which proposes a flexible-grid or gridless, where the spectral width changes according to the bandwidth demand and allows optimizing the spectral efficiency with a minimum separation between adjacent channels. In this paper, we present a comprehensive survey of elastic optical networks, introducing new concepts and describing the challenges and the limitations in these networks. Recent experimental reports show new technological concepts related to the commercials 100-G systems such as: design of multichannels transmitters, gridless Nyquist-WDM and Optical-OFDM, reconfigurable digital coherent receivers, optical dynamic spectrum allocation and advanced modulation formats. Nevertheless, the nonlinearity effects of the optical fiber are a significant limitation that must be researched in detail in this new elastic scenario. Hence, it is shown how the digital signal processing techniques are going to play an important role in order to get high capacity in elastic and reconfigurable networksPalabras clave: Comunicaciones por Fibra Óptica, Enrutamiento, Interferencia Intercanal (ICI), Multiplexación por División de Longitud de Onda, Óptica No-Lineal, Procesamiento Digital de Señales (DSP), Redes Ópticas.

Control and Operation to Hybrid Optical Network

2011 ◽  
Vol 186 ◽  
pp. 576-580
Author(s):  
Ning Zhang
Keyword(s):  
Optical Networks ◽  
Wavelength Division Multiplexing ◽  
Traffic Management ◽  
Optical Network ◽  
Network Models ◽  
Optical Switches ◽  
Telecommunication Networks ◽  
Data Traffic ◽  
Wavelength Division ◽  
Network Load

In this paper, a novel hybrid optical network system is presented. The continuing increase of data traffic keeps the pressure on the backbone telecommunication networks requiring more diverse and more intelligent allocation of capacity. Optical networking has become a key technology in accommodating the rapidly expanding Internet traffic. Hybrid nodes are now playing a key role in optical networks by facilitating efficient traffic management. New optical networks are expected to support the increasing network load by employing both sophisticated transmission (wavelength division multiplexing division (WDM)) and switching technologies (optical switches and cross-connects). This study will explain how the hybrid nodes achieve with different network models and make it operation through innovative technical designs.

Performance Modeling and Analysis of WDM Optical Networks under Wavelength Continuity Constraint using MILP

2020 ◽  
Vol 13 (2) ◽  
pp. 203-211 ◽  
Author(s):  
Swati Bhalaik ◽  
Ashutosh Sharma ◽  
Rajiv Kumar ◽  
Neeru Sharma
Keyword(s):  
Network Design ◽  
Optical Networks ◽  
Wavelength Division Multiplexing ◽  
Optical Network ◽  
Optimal Path ◽  
Topology Design ◽  
Mixed Integer ◽  
Wdm Optical Networks ◽  
Virtual Topology ◽  
Wdm Network

Objective: Optical networks exploit the Wavelength Division Multiplexing (WDM) to meet the ever-growing bandwidth demands of upcoming communication applications. This is achieved by dividing the enormous transmission bandwidth of fiber into smaller communication channels. The major problem with WDM network design is to find an optimal path between two end users and allocate an available wavelength to the chosen path for the successful data transmission. Methods: This communication over a WDM network is carried out through lightpaths. The merging of all these lightpaths in an optical network generates a virtual topology which is suitable for the optimal network design to meet the increasing traffic demands. But, this virtual topology design is an NP-hard problem. This paper aims to explore Mixed Integer Linear Programming (MILP) framework to solve this design issue. Results: The comparative results of the proposed and existing mathematical models show that the proposed algorithm outperforms with the various performance parameters. Conclusion: Finally, it is concluded that network congestion is reduced marginally in the overall performance of the network.

Performance Enhancement of Encoding–Decoding Multidiagonal and Walsh Hadamard Codes for Spectral Amplitude Coding-Optical Code Division Multiple Access (SAC-OCDMA) Utilizing Dispersion Compensated Fiber

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Majidah H. Majeed ◽  
Riyadh Khlf Ahmed
Keyword(s):  
Multiple Access ◽  
Performance Enhancement ◽  
Optical Network ◽  
Spectral Amplitude ◽  
Q Factor ◽  
Data Traffic ◽  
Eye Diagram ◽  
Multiple User ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

AbstractSpectral Amplitude Coding-Optical Codes Division Multiple Access (SAC-OCDMA) is a future multiplexing technique that witnessed a dramatic attraction for eliminating the problems of the internet in optical network field such as multiple-user access and speed’s growth of the files or data traffic. In this research article, the performance of SAC-OCDMA system based on two encoding–decoding multidiagonal (MD) and Walsh Hadamard (WH) codes is enhanced utilizing three different schemes of dispersion compensating fiber (DCF): pre-, post- and symmetrical compensation. The system is simulated using Optisystem version 7.0 and Optigrating version 4.2. The performance of the proposed system is specified in terms of bit error rate (BER), Q-factor and eye diagram. It has been observed that the compensated system based on MD code is performs much better compared to the system based on WH code. On the other hand, the compensated SAC-OCDMA system with symmetrical DCF has the lowest values of BER and largest values of Q-factor, so it is considered the best simulated scheme contrasted with pre- and post-DCF.

scholarly journals The Traffic Grooming Problem in Optical Networks with Respect to ADMs and OADMs: Complexity and Approximation

Algorithms ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 151
Author(s):  
Michele Flammini ◽  
Gianpiero Monaco ◽  
Luca Moscardelli ◽  
Mordechai Shalom ◽  
Shmuel Zaks
Keyword(s):  
Cost Function ◽  
Optical Networks ◽  
Cost Minimization ◽  
Convex Combination ◽  
Optical Network ◽  
Switching Cost ◽  
Wavelength Assignment ◽  
Intermediate Node ◽  
Polynomial Time Approximation Algorithm ◽  
Path Topology

All-optical networks transmit messages along lightpaths in which the signal is transmitted using the same wavelength in all the relevant links. We consider the problem of switching cost minimization in these networks. Specifically, the input to the problem under consideration is an optical network modeled by a graph G, a set of lightpaths modeled by paths on G, and an integer g termed the grooming factor. One has to assign a wavelength (modeled by a color) to every lightpath, so that every edge of the graph is used by at most g paths of the same color. A lightpath operating at some wavelength λ uses one Add/Drop multiplexer (ADM) at both endpoints and one Optical Add/Drop multiplexer (OADM) at every intermediate node, all operating at a wavelength of λ. Two lightpaths, both operating at the same wavelength λ, share the ADMs and OADMs in their common nodes. Therefore, the total switching cost due to the usage of ADMs and OADMs depends on the wavelength assignment. We consider networks of ring and path topology and a cost function that is a convex combination α·|OADMs|+(1−α)|ADMs| of the number of ADMs and the number of OADMs deployed in the network. We showed that the problem of minimizing this cost function is NP-complete for every convex combination, even in a path topology network with g=2. On the positive side, we present a polynomial-time approximation algorithm for the problem.

scholarly journals Modelling and Optimization of Multi-Service Optical Switching Networks with Threshold Management Mechanisms

Electronics ◽  
2021 ◽  
Vol 10 (13) ◽  
pp. 1515
Author(s):  
Maciej Sobieraj ◽  
Piotr Zwierzykowski ◽  
Erich Leitgeb
Keyword(s):  
Optical Networks ◽  
Traffic Management ◽  
Optical Switching ◽  
Optical Network ◽  
Research Work ◽  
Simulation Environment ◽  
Switching Networks ◽  
Traffic Characteristics ◽  
Threshold Mechanism ◽  
Optical Switching Networks

DWDM networks make use of optical switching networks that allow light waves of multiple lengths to be serviced and provide the possibility of converting them appropriately. Research work on optical switching networks focuses on two main areas of interest: new non-blocking structures for optical switching networks and finding traffic characteristics of switching networks of the structures that are already well known. In practical design of switching nodes in optical networks, in many cases, the Clos switching networks are successfully used. Clos switching networks are also used in Elastic Optical Networks that can effectively manage allocation of resources to individual multi-service traffic streams. The research outcomes presented in this article deal with the problems of finding traffic characteristics in blocking optical switching networks with known structures. This article aims at presenting an analysis of the influence of traffic management threshold mechanisms on the traffic characteristics of multi-service blocking Clos switching networks that are used in the nodes of elastic optical networks as well as their influence on the traffic efficiency of network nodes. The analysis was carried out on the basis of research studies performed in a specially dedicated purpose-made simulation environment. The article presents a description of the simulation environment used in the experiments. The study was focused on the influence of the threshold mechanism, which is one of the most commonly used and elastic traffic management mechanisms, and on the traffic characteristics of switching networks that service different mixtures of multi-service Erlang, Engset and Pascal traffic streams. The conducted study validates the operational effectiveness and practicality of the application of the threshold mechanism to model traffic characteristics of nodes in an elastic optical network.

scholarly journals Machine Learning Classification and Regression Approaches for Optical Network Traffic Prediction

Electronics ◽  
2021 ◽  
Vol 10 (13) ◽  
pp. 1578
Author(s):  
Daniel Szostak ◽  
Adam Włodarczyk ◽  
Krzysztof Walkowiak
Keyword(s):  
Machine Learning ◽  
Optical Networks ◽  
Network Traffic ◽  
Optical Network ◽  
Optimization Methods ◽  
Supervised Machine Learning ◽  
Traffic Prediction ◽  
Machine Learning Classification ◽  
Classification And Regression ◽  
Network Technologies

Rapid growth of network traffic causes the need for the development of new network technologies. Artificial intelligence provides suitable tools to improve currently used network optimization methods. In this paper, we propose a procedure for network traffic prediction. Based on optical networks’ (and other network technologies) characteristics, we focus on the prediction of fixed bitrate levels called traffic levels. We develop and evaluate two approaches based on different supervised machine learning (ML) methods—classification and regression. We examine four different ML models with various selected features. The tested datasets are based on real traffic patterns provided by the Seattle Internet Exchange Point (SIX). Obtained results are analyzed using a new quality metric, which allows researchers to find the best forecasting algorithm in terms of network resources usage and operational costs. Our research shows that regression provides better results than classification in case of all analyzed datasets. Additionally, the final choice of the most appropriate ML algorithm and model should depend on the network operator expectations.

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