In this paper, we describe and experimentally evaluate the performance of our Network Link Outlier Factor (NLOF) for detecting soft-failures in communication networks. The NLOF is computed using the throughput values derived from NetFlow records. The flow throughput values are clustered in two stages, outlier values are determined within each cluster, and the flow outliers are used to compute the outlier factor or score for each network link. When sampling NetFlow records across the full span of a network, NLOF enables the detection of soft-failures across the span of the network; large NLOF scores correlate well with links experiencing failure.
Much of the related work implements active probing techniques @cite_16 @cite_17 @cite_13 . These techniques use probe messages to infer the state of links and require optimal probe placement @cite_3 @cite_9 @cite_12 to trade off measurement with resource consumption. More recent work @cite_10 uses passive data (e.g., number of: flows, lost packets, average packet delay) and compares the performance of several machine learning techniques (e.g., random forests and multi-layer perceptrons) to localize faults. Their results are compared to the active probing technique in @cite_2 . Other recent work in the domain of optical networking uses passively collected physical layer data and machine learning to detect and or localize faults @cite_5 @cite_11 .
@cite_11 @cite_10 @cite_9 @cite_3 @cite_2 @cite_5 @cite_16 @cite_13 @cite_12 @cite_17
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Communication networks such as wireless sensor networks, Internet of Things and vehicular ad-hoc networks are becoming more complex and increasing in size. This leads to high overhead (network and computation) and difficulty in determining the accurate network topology, which is an important information for traffic engineering and network management. Localization of link failures in such networks is a challenging problem and requires a novel approach to achieve the goal without any prior information about the network topology. In this paper, we present a traffic engineering (TE)-based machine learning approach to detect and localize link failures. Instead of using topology information and actively injecting additional packets to localize a failed link, the proposed machine learning model adopts a passive mechanism to learn the network traffic behavior from propagation delay, number of flows and average packet loss at every node in the network under normal working conditions and failure scenarios. We train the learning model with machine learning algorithms such as naive Bayes, logistic regression, support vector machine, multi-layer perceptron, decision tree and random forest. We implement the proposed approach and carry out extensive experiments using the Mininet platform. The performance study shows that our proposed approach localizes link failures with at least 90 accuracy using random forest algorithm while requiring less time-to-localization of a link failure compared to other existing works. Increase in the network usage for more and more performance critical applications has caused a demand for tools that can monitor network health with minimum management traffic. Adaptive probing has the potential to provide effective tools for end-to-end monitoring and fault diagnosis over a network. Adaptive probing based algorithms adapt the probe set to localize faults in the network by sending less probes in healthy areas and more probes in the suspected areas of failure. In this paper we present adaptive probing tools that meet the requirements to provide an effective and efficient solution for fault diagnosis for modern communication systems. We present a system architecture for adaptive probing based fault diagnosis tool and propose algorithms for probe selection to perform failure detection and fault localization. We compare the performance and efficiency of the proposed algorithms through simulation results. We consider the problem of identifying the source of failure in a network after receiving alarms or having observed symptoms. To locate the root cause accurately and timely in a large communication system is challenging because a single fault can often result in a large number of alarms, and multiple faults can occur concurrently. In this paper, we present a new fault localization method using a machine-learning approach. We propose to use logistic regression to study the correlation among network events based on end-to-end measurements. Then based on the regression model, we develop fault hypothesis that best explains the observed symptoms. Unlike previous work, the machine-learning algorithm requires neither the knowledge of dependencies among network events, nor the probabilities of faults, nor the conditional probabilities of fault propagation as input. The “low requirement” feature makes it suitable for large complex networks where accurate dependencies and prior probabilities are difficult to obtain. We then evaluate the performance of the learning algorithm with respect to the accuracy of fault hypothesis and the concentration property. Experimental results and theoretical analysis both show satisfactory performance. In elastic optical networks (EONs), effective soft failure localization is of paramount importance to early detection of service level agreement violations while anticipating possible hard failure events. So far, failure localization techniques have been proposed and deployed mainly for hard failures, while significant work is still required to provide effective and automated solutions for soft failures, both during commissioning testing and in-operation phases. In this paper, we focus on soft failure localization in EONs by proposing two techniques for active monitoring during commissioning testing and for passive in-operation monitoring. The techniques rely on specifically designed low-cost optical testing channel (OTC) modules and on the widespread deployment of cost-effective optical spectrum analyzers (OSAs). The retrieved optical parameters are elaborated by machine learning-based algorithms running in the agent's node and in the network controller. In particular, the Testing optIcal Switching at connection SetUp timE (TISSUE) algorithm is proposed to localize soft failures by elaborating the estimated bit-error rate (BER) values provided by the OTC module. In addition, the FailurE causE Localization for optIcal NetworkinG (FEELING) algorithm is proposed to localize failures affecting a lightpath using OSAs. Extensive simulation results are presented, showing the effectiveness of the TISSUE algorithm in properly exploiting OTC information to assess BER performance of quadrature-phase-shift-keying-modulated signals, and the high accuracy of the FEELING algorithm to correctly detect soft failures as laser drift, filter shift, and tight filtering. In this paper, we consider boolean network tomography to identify link failures in a network. In boolean network tomography, the relationship between end-to-end measurements and link states are represented with a system of boolean equations, and failure links are identified by solving the equations. In order to establish measurement paths efficiently, we propose an adaptive boolean network tomography scheme, where measurement paths are established sequentially according to a candidate set of failure links. Here, to derive the candidate set, we extend CBP (Combinatorial Basis Pursuit), a representative decoding algorithm in Combinatorial Group Testing, and utilize its property that it can identify failure links without false negative errors. We evaluate the performance of the proposed scheme in terms of the number of measurement paths and compare it with a non-adaptive boolean network tomography scheme. Furthermore, we propose mobility-assisted boolean network tomography, which can improve the ambiguity problem in boolean network tomography.