Survivable Optical Networks Research Articles

A Survey on Fault Identification System in OTN using Neural Network

The diversity of information and services that are sent via optical networks is growing day by day, hence the survivability of optical networks has emerged as a significant research issue in recent years. The location of the fault in an optical transmission network (OTN) is very important when investigating the survivability of optical networks. The first step is to create network model with three channel, after which it is necessary to analyze common alarm data, as well as fault monitoring points and common fault sites. The fault location field of OTN incorporates the artificial neural network (ANN), which is used to identify whether or not a probable fault site is present. In this paper, we had done a review of earlier research work in this field and identified the research gap in the introduction of neural networks into the area of fault identification in optical transport networks.

Spectrum-Sharing-Maximized Approaches With Shared-Path Protection in Elastic Optical Data Center Networks

The spectrum efficiency is a greatly important issue when we establish connection requests in elastic optical data center networks (EODCNs). In this article, we address the spectrum efficiency problems of the shared-path protection with spectrum-sharing-maximized approaches for the optical network survivability. Two integer linear program (ILP) models, i.e., flow-based and path-based ILP models, named FB-ILP and PB-ILP, are developed to minimize the frequency slots (FSs) occupied with the spectrum-sharing-maximized protection, and two heuristic approaches with the spectrum-sharing-maximized protection (HA-SSMP) and with the general spectrum-sharing protection (HA-GSSP) are also proposed to improve spectrum efficiency in EODCNs. For comparison, we introduce a heuristic approach with the existing shared-path protection (HA-ESPP) in EODCNs. On the one hand, simulation results show that FB-ILP can minimize the number of FSs occupied, but leads to the higher average number of hops and longer running time compared to PB-ILP, HA-SSMP, HA-GSSP, and HA-ESPP in static traffic scenario in EODCNs. On the other hand, the simulation results of our proposed HA-SSMP are very close to the solutions of FB-ILP. In dynamic traffic scenario, simulation results show that HA-SSMP significantly improves the spectrum efficiency and effectively suppresses the blocking probability, but leads to the higher average number of hops compared to HA-GSSP and HA-ESPP in EODCNs.

Reflective fiber fault detection and characterization using long short-term memory

To reduce operation-and-maintenance expenses (OPEX) and to ensure optical network survivability, optical network operators need to detect and diagnose faults in a timely manner and with high accuracy. With the rapid advancement of telemetry technology and data analysis techniques, data-driven approaches leveraging telemetry data to tackle the fault diagnosis problem have been gaining popularity due to their quick implementation and deployment. In this paper, we propose a novel multitask learning model based on long short-term memory to detect, locate, and estimate the reflectance of fiber reflective faults (events) including the connectors and the mechanical splices by extracting insights from monitored data obtained by the optical time-domain reflectometry principle commonly used for troubleshooting of fiber optic cables or links. The experimental results prove that the proposed method (i) achieves a good detection capability and high localization accuracy within a short measurement time even for low SNR values and (ii) outperforms conventionally employed techniques.

Integration of fiber and FSO network with fault-protection for optical access network

In this paper, we proposed and experimentally demonstrated the integration of optical fiber and free-space optic (FSO) with fault protection for the optical access network. The proposed architecture has a fault protection or self-healing function when a link failure is occurred in the network. Thus, the proposed self-healing architecture is a promising network for improved reliability and survivability of optical network especially for the remote area when the fiber is broken or cut between each remote node (RN) and optical network unit (ONU). Moreover integration of optical fiber with the FSO network is used to increase the coverage range of the broadband wireless network and improve the flexibility of the network. In the experiment, the signal is generated by using the signal generator, and propagates through a hybrid of 25 km SMF, and FSO link and then transmitted into each ONU. Finally, we compare and evaluate the signal transmission performance of channels in terms of bit error rate (BER) and error vector magnitude (EVM) after back-to-back (BTB) transmission, 25 km SMF transmission, and after a hybrid of 25 km SMF with FSO link transmission. The experimental result proves that the hybrid of 25 km SMF with FSO link increases the communication coverage range with a reasonable performance.

Novel approach to jointly optimize working and spare capacity of survivable optical networks

Abstract As technology advancing day by day, the data rate of optical network is moving towards Tb/s speed. The minimum capacity utilization and survivability are the crucial requirement in such high speed optical networks. This research work presents a new approach to calculate both working and spare capacity with the help of single mathematical programming model named as joint capacity planning model. The working traffic and restored traffic are routed jointly in proposed joint capacity planning model. Therefore the joint capacity planning model required minimum capacity in as compare to other optimization models. To evaluate our model, three example networks are proposed i.e., network A (6 node), network B (8 node) & National science foundation network (14 node). Results of these networks are analyzed and compared. The capacity utilization is optimized by increasing the backup paths of the optical networks. It has also been proved in this manuscript that capacity requirement is dependent on the backup path. The proposed joint capacity model provides fast restoration speed and guaranteed protection for optical network.

A Holistic Survey on Disaster and Disruption in Optical Communication Network

Background: This paper is a review of optical fiber communications and also presents the different types of disasters and different protection schemes to combat these disasters. In the optical communication network, the failure of a network caused by disasters (e.g. predictable disaster, unpredictable disaster, Intentional attacks) leads to the failure of several optical communication channels and huge data loss. Most of the previous works on optical network survivability assume that the failures are going to occur in future, and the network is made survivable to ensure connectivity in events of failures. With the advancements in technology, the predictions of tornados, cyclone and landslides are becoming more accurate by using some early warning systems. Objective: Significant improvement in optical communication network survivability can be achieved using our proposed protection scheme in the event of a major earthquake, cloud burst and landslides. Conclusion: The review concludes that a large amount of data could be lost even if there is a very short disruption in the optical backbone network.

Network coding for improving throughput in WDM optical networks with dedicated protection

Network coding (NC) has been recently emerging as an excellent technique for leveraging network efficiency. In optical networks, NC and protection appear to be a good match and indeed, NC could be effectively exploited for greater protection efficiency thanks to the opportunity of combining signals rather than duplication in the traditional approach. Motivated by this observation, we investigate the application of a simple and practical NC technique based on XOR operation to improve the network throughput in survivable optical networks. To this end, we propose the NC-based protection whose speed recovery is on a par with the conventional $$1+1$$ dedicated protection while the capacity usage could be more efficient, paving the way for improving throughput in constrained capacity conditions. A novel mixed integer linear programming model is developed for survivable optical networks design employing the proposed NC-based protection. The model attempts to optimally determine the demands to serve, the routing for served demands and NC assignment among demands aiming at maximizing the network throughput in the constraint of bandwidth limitation. Extensive numerical evaluations on realistic topologies are provided to highlight the advantages of our NC-based protection proposal compared with the conventional dedicated protection in improving the network throughput. Encouraging results are observed when the new protection proposal based on NC could accommodate up to $$30\%$$ more traffic than the conventional case.

Maximizing double-link failure recovery of over-dimensioned optical mesh networks

Double-link failure models, in which any two links in the network fail in an arbitrary order, are becoming critical in survivable optical network designs. Optical networks that are over-dimensioned and purposely preplanned for full protection against any single-link failure may not survive well in an event of a double-link failure. It is therefore important to understand how much impact a subsequent second link failure may have upon traffic recovery of both failed links. This paper primarily aims to investigate traffic recoverability when a double-link failure occurs. We propose several methods for improving traffic recovery without using additional backup capacities other than the existing backup resources available for single-link failure recovery. In each proposed method, integer linear programming formulation is derived to optimize the backup resource allocation. Numerical results on various network configurations have shed some light on how network operators can choose one of five alternative methods to better handle a double-link failure. From numerical results, Method 1 offers some improvement on the traffic recoverability of the second failed link without disturbing the recovered traffic of the first failed link. Method 2 reveals that the traffic recoverability of the first failed link can be improved if the backup routes of the unrecovered traffic of the first failed link can be reassigned. Method 3 is useful for maximizing the traffic recoverability of the first failed link. Method 4 further increases the recoverability of the second failed link while maintaining the same recoverability of the first failed link as Method 3. Finally, Method 5 accomplishes the maximum overall traffic recoverability.

Application of neural network in fault location of optical transport network

Due to the increasing variety of information and services carried by optical networks, the survivability of network becomes an important problem in current research. The fault location of OTN is of great significance for studying the survivability of optical networks. Firstly, a three-channel network model is established and analyzing common alarm data, the fault monitoring points and common fault points are carried out. The artificial neural network is introduced into the fault location field of OTN and it is used to judge whether the possible fault point exists or not. But one of the obvious limitations of general neural networks is that they receive a fixed-size vector as input and produce a fixed-size vector as the output. Not only that, these models is even fixed for mapping operations (for example, the number of layers in the model). The difference between the recurrent neural network and general neural networks is that it can operate on the sequence. In spite of the fact that the gradient disappears and the gradient explodes still exist in the neural network, the method of gradient shearing or weight regularization is adopted to solve this problem, and choose the LSTM (long-short tenn memory networks) to locate the fault. The output uses the concept of membership degree of fuzzy theory to express the possible fault point with the probability from 0 to 1. Priority is given to the treatment of fault points with high probability. The concept of F-Measure is also introduced, and the positioning effect is measured by using location time, MSE and F-Measure. The experiment shows that both LSTM and BP neural network can locate the fault of optical transport network well, but the overall effect of LSTM is better. The localization time of LSTM is shorter than that of BP neural network and the Fl-score of LSTM can reach 0.961566888396156 after 45 iterations, which meets the accuracy and real-time requirements of fault location. Therefore, it has good application prospect and practical value to introduce neural network into the fault location field of optical transport network.

Survivability reconfigurable techniques in optical network

Survivability plays a vital role against to stop the failure. It results the demand distribution in Optical Networks through different communication services like data voice and video by using huge bandwidth. In this paper Techniques for Survivability of Optical Networks through Network Configuration is presented Hence the centralized and non-centralized demand distribution in Optical Networks through different communication services like data voice and video by using huge bandwidth. In this paper Techniques for Survivability of Optical Networks through Network Configuration is presented. Hence these techniques are evaluated by using the parameters such as Traffic Characterization (TC), Traffic Protection and Restoration (TPR), Network Path Configuration and Network Integration w.r.t. Physical Layer(PL) and Logical Layer(LL) problem formulation(s) are discussed. Hence the survivability of fiber Optic Network play a vital role for NXN connectivity. Reconfigurable implies Optical Network Services Utilization Factor(ONSUF) is estimated through the local and global connectivity scenario.

Network and Risk Modeling for Disaster Survivability Analysis of Backbone Optical Communication Networks

In recent years, survivability of optical communication networks against large-scale disaster failures has been studied. The survivability analyses done by most of the studies are based on arbitrary simplified disaster areas under the assumption of uniform disaster occurrence in a given area, and short-term evaluation of network robustness. However, for assessing the generic applicability and evaluating the performance of any protection, recovery, and/or topology design scheme irrespective of the varying geographical region and network topology, a stochastic model for disaster occurrence and optical network topology would be useful. In this paper, we propose a stochastic model to estimate the impact of earthquake disasters on a backbone optical network, namely, earthquake risk and backbone optical network (ERBON) model. We consider various stochastic distributions, real statistics, stochastic geometry, and graph theory to model seismic zonation, epicenter location and density, earthquake magnitudes, link/node failures, and network topology/connectivity. Furthermore, we propose an earthquake risk minimized node relocation (ERMNR) scheme that can improve the optical network's survivability. Performance of the proposed ERMNR scheme is evaluated under the proposed ERBON model and for real-world earthquake risk data from the U.S. and India.

Spectrum efficient distance-adaptive paths for fixed and fixed-alternate routing in elastic optical networks

Abstract Efficient utilization of spectrum is a key concern in the soon to be deployed elastic optical networks (EONs). To perform routing in EONs, various fixed routing (FR), and fixed-alternate routing (FAR) schemes are ubiquitously used. FR, and FAR schemes calculate a fixed route, and a prioritized list of a number of alternate routes, respectively, between different pairs of origin o and target t nodes in the network. The route calculation performed using FR and FAR schemes is predominantly based on either the physical distance, known as k -shortest paths (KSP), or on the hop count (HC). For survivable optical networks, FAR usually calculates link-disjoint (LD) paths. These conventional routing schemes have been efficiently used for decades in communication networks. However, in this paper, it has been demonstrated that these commonly used routing schemes cannot utilize the network spectral resources optimally in the newly introduced EONs. Thus, we propose a new routing scheme for EON, namely, k -distance adaptive paths (KDAP) that efficiently utilizes the benefit of distance-adaptive modulation, and bit rate-adaptive superchannel capability inherited by EON to improve spectrum utilization. In the proposed KDAP, routes are found and prioritized on the basis of bit rate, distance, spectrum granularity, and the number of links used for a particular route. To evaluate the performance of KSP, HC, LD, and the proposed KDAP, simulations have been performed for three different sized networks, namely, 7-node test network (TEST7), NSFNET, and 24-node US backbone network (UBN24). We comprehensively assess the performance of various conventional, and the proposed routing schemes by solving both the RSA and the dual RSA problems under homogeneous and heterogeneous traffic requirements. Simulation results demonstrate that there is a variation amongst the performance of KSP, HC, and LD, depending on the o - t pair, and the network topology and its connectivity. However, the proposed KDAP always performs better for all the considered networks and traffic scenarios, as compared to the conventional routing schemes, namely, KSP, HC, and LD. The proposed KDAP achieves up to 60 % , and 10.46 % improvement in terms of spectrum utilization, and resource utilization ratio, respectively, over the conventional routing schemes.

Security threats and protection procedures for optical networks

This study addresses the issues of optical network survivability to attacks in the optical physical layer. The authors comprehensively review and discuss the vulnerability of optical networks towards various types of security threats that could appear in the network optical layer: passive eavesdropping attacks and active optical attacks like in-band jamming, out-of-band crosstalk attacks, amplifier attacks and physical infrastructure attacks. They describe and discuss several protection procedures and monitoring techniques to improve network attack survivability. Numerical simulation performances of some attacks and protection schemes are also provided.

Partitioning-based approach to control the restored path length in p-cycle-based survivable optical networks

In recent years, p-cycles have been widely investigated for survivability of WDM networks. They provide fast recovery speed such as ring and capacity efficiency as mesh survivability schemes. However, restoration paths are very long, which causes excessive latency and intolerable physical impairments. On the other hand, nowadays, a wide set of applications require an optical path with almost no delay. The existing approaches, namely loopbacks removal and inter-cycle switching, provide a significant reduction in the restored path, but even then a number of restored paths remain many times longer than the working path lengths. In this paper, we propose a network partitioning-based approach to control the length of each restored path as per delay sustainability of time critical applications. The basic idea of the work is to partition the network into domains and construct the p-cycles for each domain independently. The domain wise construction of p-cycles restricts their length, which consequently reduces the length of restored paths. Here, we introduce a new concept where the selected border nodes are overlapped among adjacent domains to cover inter-domain spans of the network as a domain span in order to ensure their survivability through domain p-cycles. Simulation results show that the proposed solution is good enough to control the restored path length with small augmentation in redundancy of spare capacity as compared to optimal design of p-cycles. More importantly, it enhances the dual failure restorability significantly.

A Multi-Backup Path Protection scheme for survivability in Elastic Optical Networks

Abstract Two important challenges in designing a survivable optical network are minimizing backup spectrum allocation and ensuring spectrum assignment constraints. Allocating backup spectrum is one important approach for survivable optical network design. Connection requests which are rejected due to the unavailability of a single backup path can be survived using multiple backup routes. Multiple backup routes not only increase connection acceptance rate, but also improve backup resource sharing. In this paper, we present a strategy for survivability which optimizes primary and backup spectrum allocations and multiple backup route assignments for surviving a connection request. In our strategy, named as Backup Spectrum Reservation with MultiPath Protection (BSR-MPP), multiple backup routes are searched over advance reserved backup resources when an optical connection is concerned. Simulation results show that confinement of backup resources result in higher resource sharing and assignment of multiple backup lightpaths. It can also be observed that BSR-MPP has lower Bandwidth Blocking Probability and higher spectrum efficiency as compared to conventional Shared Path Protection (SPP) and MultiPath Protection (MPP) strategies.

Optimization of routing algorithms in survivable optical networks

Optimization of routing algorithms in survivable optical networks

Optimization of routing algorithms in survivable optical networks

Optimization of routing algorithms in survivable optical networks

Passive Optical Network Survivability: Protection, Detection and Restoration

Passive optical network (PON) technologies have received increasing attention as demand for fibre access networks has grown. Enhancing fibre access network reliability provides lower operational costs, and improves customer satisfaction. This paper discusses PON survivability including protection schemes for the fiber link and the Optical Line Terminal (OLT), the exciting monitoring techniques of the fiber link, and the effect of reducing the restoration time on the network availability. The main contribution of this study is to provide two protection schemes namely OLT-only-protected and OLT-and-ring protected. The proposed schemes are designed to handle instances of single failure affecting all customers in the network. This work considers three key performance metrics- Failure Impact Robustness (FIR), cost, and availability. The objective of the proposed protection architectures is to guarantee high quality of service at low costs by protecting critical network elements such as OLT and fiber ring. The proposed architectures have been compared with other well-known protection schemes. The results postulate that OLT-and-ring protected approach has 99.993% availability with a 0.09% increase in cost compared to the ring-only protection architecture.

Protection Approach against SRLG Failure for Survivable Long-Reach Passive Optical Network in Smart Grid

Long-Reach Passive Optical Network (LR-PON) is widely acknowledged as a promising solution for communication system in smart grid. Survivability is one of the key issues in the planning of LR-PON because massive high-rate traffic flows may be interrupted in case of network component failure. However, the survivability issue of LR-PON is addressed in few works. Most of previous works focus on single distribution fiber failure and remain untouched the simultaneous failure of multiple distribution fibers. In this paper, we focus on the survivability of LR-PON against single Shared-Risk Link Group (SRLG) failure. A reliability model is proposed to represent the probability of reliable connection for each Optical Network Unit (ONU). Based on this reliability model, we propose a novel Backup Fibers Protection (BFP) approach, aiming at the optimization of joint allocating backup capacity and deploying backup fibers. Through extensive simulation, we investigate the performance of BFP and demonstrate its effectiveness in different scenarios.

Differentiated quality-of-protection provisioning with probabilistic-shared risk link group in survivable flexi-grid optical networks

A multilink failures model, i.e., probabilistic-shared risk link group (PSRLG), is adopted to investigate the problem of differentiated quality-of-protection (QoP) provisioning for flexi-grid optical networks. As a metric, service failure probability (SFP) is introduced to exactly examine the feasibility of differentiated QoP schemes, which denotes the failure probability of a connection during transmission. According to different reliability require- ments, connection requests are divided into three classes, i.e., class high, class middle, and class low. Then two differentiated QoP provisioning schemes are proposed based on the class division, i.e., intraclass-shared re- source scheme (ICSR scheme) and cross-class-shared resource scheme (CCSR scheme). The former allows a connection to share backup resources only with those connections in the same class, whereas the latter enables the connections in different classes to share backup resources. Simulation results show that our proposed schemes could well provide differentiated reliability with PSRLG constraint and achieve a good balance between reliability and resource efficiency. Moreover, the CCSR scheme achieves lower blocking probability, lower re- source redundancy, and higher spectrum utilization without sacrificing reliability compared to the ICSR scheme. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in