Djamel Sadok

Bio: Djamel Sadok is an academic researcher from Federal University of Pernambuco. The author has contributed to research in topics: The Internet & Cloud computing. The author has an hindex of 22, co-authored 164 publications receiving 2214 citations. Previous affiliations of Djamel Sadok include Universidade de Pernambuco.

A Survey on Internet Traffic Identification

Abstract: The area of Internet traffic measurement has advanced enormously over the last couple of years. This was mostly due to the increase in network access speeds, due to the appearance of bandwidth-hungry applications, due to the ISPs' increased interest in precise user traffic profile information and also a response to the enormous growth in the number of connected users. These changes greatly affected the work of Internet service providers and network administrators, which have to deal with increasing resource demands and abrupt traffic changes brought by new applications. This survey explains the main techniques and problems known in the field of IP traffic analysis and focuses on application detection. First, it separates traffic analysis into packet-based and flow-based categories and details the advantages and problems for each approach. Second, this work cites the techniques for traffic analysis accessible in the literature, along with the analysis performed by the authors. Relevant techniques include signature-matching, sampling and inference. Third, this work shows the trends in application classification analysis and presents important and recent references in the subject. Lastly, this survey draws the readers' interest to open research topics in the area of traffic analysis and application detection and makes some final remarks.

Resource allocation for distributed cloud: concepts and research challenges

Abstract: In a cloud computing environment, dynamic resource allocation and reallocation are keys for accommodating unpredictable demands and, ultimately, contribute to investment return. This article discusses this process in the context of distributed clouds, which are seen as systems where application developers can selectively lease geographically distributed resources. This article highlights and categorizes the main challenges inherent to the resource allocation process particular to distributed clouds, offering a stepwise view of this process that covers the initial modeling phase through to the optimization phase.

A Survey on Open-source Cloud Computing Solutions

Abstract: Cloud computing is an attractive computing model since it allows for resources to be provisioned according on a demand basis, i.e., cloud users can rent resources as they become necessary. This model motivated several academic and non-academic institutions to develop open-source cloud solutions. This paper presents and discusses the state-of-the of open-source solutions for cloud computing. The authors hope that the observation and classification of such solutions can leverage the cloud computing research area providing a good starting point to cope with some of the problems present in cloud computing environments.

Evaluation of security mechanisms in wireless sensor networks

Abstract: Ad hoc and wireless sensor networks have recently emerged as successful technologies in a number of application domains. The need to build security services into them remains however a considerable challenge as the hardware used often shows serious processing and energy limitations. This work evaluates the impact of a number of security mechanism on sensor nodes and the network as a whole. Hence a number of actual measurements were undertaken in a real sensor platform in order to accurately establish energy consumption for various encryption algorithms; as well the baseline scenario obtained when none of these is used. Measurements have shown that integrity code length added to application messages using some cryptography algorithms and MAC (message authentication code) is acceptable for a sensor node with 128 kB of ROM memory and 4 kB of RAM (MICA2). We also were able to check that power consumption of the encryption process does not in itself cause representative impact, since it is in the micro-joules range.

High availability in clouds: systematic review and research challenges

Abstract: Cloud Computing has been used by different types of clients because it has many advantages, including the minimization of infrastructure resources costs, and its elasticity property, which allows services to be scaled up or down according to the current demand. From the Cloud provider point-of-view, there are many challenges to be overcome in order to deliver Cloud services that meet all requirements defined in Service Level Agreements (SLAs). High availability has been one of the biggest challenges for providers, and many services can be used to improve the availability of a service, such as checkpointing, load balancing, and redundancy. Beyond services, we can also find infrastructure and middleware solutions. This systematic review has as its main goal to present and discuss high available (HA) solutions for Cloud Computing, and to introduce some research challenges in this area. We hope this work can be used as a starting point to understanding and coping with HA problems in Cloud.

Fundamentals of Queueing Theory

Abstract: Praise for the Third Edition: "This is one of the best books available. Its excellent organizational structure allows quick reference to specific models and its clear presentation . . . solidifies the understanding of the concepts being presented."IIE Transactions on Operations EngineeringThoroughly revised and expanded to reflect the latest developments in the field, Fundamentals of Queueing Theory, Fourth Edition continues to present the basic statistical principles that are necessary to analyze the probabilistic nature of queues. Rather than presenting a narrow focus on the subject, this update illustrates the wide-reaching, fundamental concepts in queueing theory and its applications to diverse areas such as computer science, engineering, business, and operations research.This update takes a numerical approach to understanding and making probable estimations relating to queues, with a comprehensive outline of simple and more advanced queueing models. Newly featured topics of the Fourth Edition include:Retrial queuesApproximations for queueing networksNumerical inversion of transformsDetermining the appropriate number of servers to balance quality and cost of serviceEach chapter provides a self-contained presentation of key concepts and formulae, allowing readers to work with each section independently, while a summary table at the end of the book outlines the types of queues that have been discussed and their results. In addition, two new appendices have been added, discussing transforms and generating functions as well as the fundamentals of differential and difference equations. New examples are now included along with problems that incorporate QtsPlus software, which is freely available via the book's related Web site.With its accessible style and wealth of real-world examples, Fundamentals of Queueing Theory, Fourth Edition is an ideal book for courses on queueing theory at the upper-undergraduate and graduate levels. It is also a valuable resource for researchers and practitioners who analyze congestion in the fields of telecommunications, transportation, aviation, and management science.

Virtual Network Embedding: A Survey

Abstract: Network virtualization is recognized as an enabling technology for the future Internet. It aims to overcome the resistance of the current Internet to architectural change. Application of this technology relies on algorithms that can instantiate virtualized networks on a substrate infrastructure, optimizing the layout for service-relevant metrics. This class of algorithms is commonly known as "Virtual Network Embedding (VNE)" algorithms. This paper presents a survey of current research in the VNE area. Based upon a novel classification scheme for VNE algorithms a taxonomy of current approaches to the VNE problem is provided and opportunities for further research are discussed.

Network Anomaly Detection: Methods, Systems and Tools

Abstract: Network anomaly detection is an important and dynamic research area. Many network intrusion detection methods and systems (NIDS) have been proposed in the literature. In this paper, we provide a structured and comprehensive overview of various facets of network anomaly detection so that a researcher can become quickly familiar with every aspect of network anomaly detection. We present attacks normally encountered by network intrusion detection systems. We categorize existing network anomaly detection methods and systems based on the underlying computational techniques used. Within this framework, we briefly describe and compare a large number of network anomaly detection methods and systems. In addition, we also discuss tools that can be used by network defenders and datasets that researchers in network anomaly detection can use. We also highlight research directions in network anomaly detection.