Network Availability and Reliability Research Papers (original) (raw)

The reliability of different graphs with vertex-specific failure probabilities is analysed, leading to conclusions about the robustness of public transport services arranged in different topologies. Three cases, which relate to different levels of user knowledge about the vertex failures are compared. The first two cases are analysed using absorbing Markov chains and consider users who have no knowledge or knowledge of the vertex failure probabilities. The final case uses a simulation approach to estimate the connectivity of the network, corresponding to users who have full knowledge about the current vertex failures. The paper highlights the importance of user information for networks with route choice and unreliable vertices.

- by and +1
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- Network Availability and Reliability, Transport network reliability

The purpose of the paper is to present a metric for availability based on the design of the information system. The availability metric proposed in this paper is twofold, based on the operating program and network delay metric of the information system (For the local bound component composition the availability metric is purely based on the software/operating program, for the remote bound component composition the metric incorporates the delay metric of the network). The aim of the paper is to present a quantitative availability metric derived from the component composition of an Information System, based on the dependencies among the individual measurable components of the system. The metric is used for measuring and evaluating availability of an information system from the security perspective, the measurements may be done during the design phase or may also be done after the system is fully functional. The work in the paper provides a platform for further research regarding the quantitative security metric (based on the components of an information system i.e. user, hardware, operating program and the network.) for an information system that addresses all the attributes of information and network security.

Reliability and Availability Engineering Modeling, Analysis, and Applications Do you need to know what technique to use to evaluate the reliability of an engineered system? This self-contained guide provides comprehensive coverage of all the analytical and modeling techniques currently in use, from classical non-state and state space approaches, to newer and more advanced methods such as binary decision diagrams, dynamic fault trees, Bayesian belief networks, stochastic Petri nets, non-homogeneous Markov chains, semi-Markov processes, and phase type expansions. Readers will quickly understand the relative pros and cons of each technique, as well as how to combine different models together to address complex, real-world modeling scenarios. Numerous examples, case studies and problems provided throughout help readers put knowledge into practice, and a solutions manual and Powerpoint slides for instructors accompany the book online. This is the ideal self-study guide for students, researchers and practitioners in engineering and computer science.

- by Kishor S Trivedi and +1
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- Fault Tolerant Computing, Probabilistic Markov Modeling, Sensitivity Analysis, Network Availability and Reliability

Un ejemplo de análisis de base de datos para determinar disponibilidad y confiabilidad de cables de fibra óptica de larga distancia.

- by Vicenc Torra
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- Information Retrieval, Computer Security, Cryptography, Databases

Cloud-based services have spread among customers, boasting a number of advantages over centralized and self- owned infrastructures. Clouds providers claim a higher resilience, due to the use of a large distributed array of servers and storage facilities. However, assessments of their actual availability are missing. Here an early attempt to provide a third-party assessment is presented. Though not disposing of first-hand measurements, we have collected data on outages from a number of sources. We use those data to evaluate the frequency and duration of outages. The average duration of outages appears to lie in the 8-10 hours range, with a significant dispersion. A statistical analysis through QQ-plots and mean excess plots shows that the tail of the distribution of outage durations is well modelled by a Generalized Pareto distribution.

Highly available cloud storage is often implemented with complex, multi-tiered distributed systems built on top of clusters of commodity servers and disk drives. Sophisticated management, load balancing and recovery techniques are needed to achieve high performance and availability amidst an abundance of failure sources that include software, hardware, network connectivity, and power issues. While there is a relative wealth of failure studies of individual components of storage systems, such as disk drives, ...

- by Luiz Barroso and +1
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- Distributed Computing, Scheduling, Parallel Processing, Cloud Computing

In this paper, we propose a novel privacy-preserving location assurance protocol for secure location-aware services over vehicular ad hoc networks (VANETs). In particular, we introduce the notion of location-aware credentials based on “hash-sign-switch” paradigm so as to guarantee the trustworthiness of location in location-aware services while providing conditional privacy preservation which is a desirable property for secure vehicular communications. Furthermore, the proposed protocol provides efficient procedures that alleviate a burden of computation for location-aware signature generation and verification on vehicles in VANETs. In order to achieve these goals, we consider online/offline signature scheme and identity-based aggregate signature scheme as our building blocks. Finally, we demonstrate experimental results to confirm the efficiency and effectiveness of the proposed protocol.

In this paper we present a novel approach for the specification of access rights in a service oriented architecture. Being part of the SECTET framework for model driven security for B2B-workflows, our specification language SECTET-PL for permissions is influenced by the OCL specification language and is interpreted in the context of UML models. Concerning the technological side, SECTET-PL specifications are translated into platform independent XACML permissions interpreted by a security gateway.

- by Julius Tapera
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- Security, Mobile Banking, Network Availability and Reliability, Speed
- by Raul Landa
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- Computer Science, Design, Graph Theory, Internet Routing Protocol
- by Mehdi Kiani
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- Production, Databases, Network Availability and Reliability, Anomaly Detection

Cloud availability is a major performance parameter for cloud platforms, but there are very few measurements on commercial platforms, and most of them rely on outage reports as appeared on specialized sites, providers' dashboards, or the general press. A paper recently presented at the PAM 2014 conference by Hu et alii reports the results of a measurement campaign. In this note, the results of that paper are summarized, highlighting sources of inaccuracy and some possible improvements. In particular, the use of a low probing frequency could lead to non detection of short outages, as well as to an inaccurate estimation of the outage duration statistics. Overcoming this lack of accuracy is relevant to properly assess SLA violations and establish the basis for insurance claims.

Paper ini menitik beratkan kepada bagaimana menjaga availability layanan konektivitas telekomunikasi. Layanan tersebut perlu didukung oleh infrastruktur jaringan yang terintegrasi di suatu wilayah ke wilayah lainnya. Salah satu infrastruktur yang menjanjikan yaitu memiliki jaringan tulang punggung yang reliable, seperti Sistem Komunikasi Kabel Laut (SKKL). Jayapura telah memiliki konektivitas jaringan yang cukup untuk memberikan jalur konektivitas yang baik mengandalkan system SKKL SMPCS, namun terkadang faktor kondisi alam maupun faktor lain dapat memengaruhi konektivitas tersebut menjadi terganggu. Akibat terburuknya yang terjadi adalaha potensi layanan blackout di wilayah tersebut mungkin terjadi. Untuk menanggulanginya agar risiko terhadap putusnya layanan berkepanjangan, teknologi lain untuk menunjang disaster recovery dipaparkan, seperti teknologi Satelit dan Radio IP. Dengan menyesuaikan karakteristik, kelebihan dan kekurangan dari masing-masing teknologi, paper ini memberikan rekomendasi sesuai Service Level Guarantee masing-masing jenis layanan. Layanan yang memiliki Quality of Service dan SLG yang dijaminkan akan diprioritaskan menggunakan konektivitas teknologi satelit, sedangkan layanan retail diprioritaskan melewati teknologi Radio IP.

- by Iwan Krisnadi
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- Network Availability and Reliability, Disaster Recovery

Abstract: This letter presents an approach to determining the impact
of supplemental reserve and high-MVA-capacity transmission lines on optimal maintenance and repair time. The impact of the supplemental reserve and high-capacity transmission lines is determined by including the availability and costs characteristics. Availability is calculated by taking into account successfully supplied consumer areas, and costs are calculated bytaking into account costs of maintenance, repair, and undelivered electric energy. The optimal maintenance and repair time is determined by considering the balance between availability and the costs. The results obtained show that the supplemental reserve and high-capacity transmission lines prolong the maintenance and repair period and reduce the costs.
Keywords: Availability, costs, maintenance, repair, undelivered energy,
supplemental reserve, transmission, power system.

We study the feasibility and time of communication in ran- dom geometric radio networks, where nodes fail randomly with positive correlation. We consider a set of radio stations with the same commu- nication range, distributed in a random uniform way on a unit square region. In order to capture fault dependencies, we introduce the ranged spot model in which damaging events, called spots, occur randomly and independently on the region, causing faults in all nodes located within distance s from them. Node faults within distance 2s become dependent in this model and are positively correlated. We investigate the impact of the spot arrival rate on the feasibility and the time of communication in the fault-free part of the network. We provide an algorithm which broadcasts correctly with probability 1 in faulty random geometric radio networks of diameter D in time O(D + log1/ ).

- by Raul Landa
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- Network Availability and Reliability, Network Routing
- by Raul Landa
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- Graph Theory, Network Availability and Reliability, Graph Embeddings, Network Routing
- by Murray Stokely
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- Distributed Computing, Scheduling, Parallel Processing, Cloud Computing
- by Amos Fiat
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- Computer Science, Digital Signature, Cryptography, Network Availability and Reliability
- by Oussama Harbouche
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- Road safety, Privacy, Mobile Computing, Security and Privacy
- by Jun Pang
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- Network Availability and Reliability, Formal Model

The performability of a wireless sensor network (WSN) can be measured using a range of metrics, including reliability (REL) and expected hop count (EHC). EHC assumes each link has a delay value of 1 and devices have no delay or vice versa, which is not necessarily appropriate for WSNs. This paper generalizes the EHC metric into an expected message delay (EMD) that permits arbitrary delay values for both links and devices. Further, it proposes a method based on Augmented Ordered Multivariate Decision Diagram (OMDD-A) that can be used to compute REL, EHC and EMD for WSN with both device and link failures. Simulation results on various networks show the benefits of the OMDD-A approach.

- by Johannes Herrmann
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- Network Availability and Reliability