Position-based routing was originally developed for packet radio networks in the 1980s [6]. It received renewed interest during the last few years as a method for routing in mobile wireless ad hoc and sensor networks [1, 2, 4]. The general idea of is to select the next hop based on position information such that the packet is forwarded in the geographical direction of the destination. Position-based routing can be divided into two main components: the location service and position-based forwarding. The location service [5, 13] is used for mapping the unique identifier (for example an IP address) of a node to its geographical position. In mobile ad hoc networks, providing accurate location service for position based routing, with low communication overhead, appears to be more difficult task than routing itself [13]. In case of sensor networks, however, destination is a sink or base station whose position is made available to source sensors by flooding. Position-based forwarding is performed by a node to select one of its neighbors as the next hop the packet should be forwarded to. Usually, the following information is required for the forwarding decision: the node's own geographical position, the position of all neighbors within transmission range and the position of the destination. Based on this information, the forwarding node selects one of its neighbors as the next hop such that the packet makes progress toward the geographical position of the destination.

Immerse yourself in the offensive security mindset to better defend against attacks In The Active Defender: Immersion in the Offensive Security Mindset, Principal Technology Architect, Security, Dr. Catherine J. Ullman delivers an expert treatment of the Active Defender approach to information security. In the book, you’ll learn to understand and embrace the knowledge you can gain from the offensive security community. You’ll become familiar with the hacker mindset, which allows you to gain emergent insight into how attackers operate and better grasp the nature of the risks and threats in your environment. The author immerses you in the hacker mindset and the offensive security culture to better prepare you to defend against threats of all kinds. You’ll also find: Explanations of what an Active Defender is and how that differs from traditional defense models Reasons why thinking like a hacker makes you a better defender Ways to begin your journey as an Active Defender and leverage the hacker mindset An insightful and original book representing a new and effective approach to cybersecurity, The Active Defender will be of significant benefit to information security professionals, system administrators, network administrators, and other tech professionals with an interest or stake in their organization’s information security.

Considering the key evolutions within the access network technologies as well as the unprecedented levels of bandwidth demands by end users, this book condenses the relentless research, design, and deployment experience of state-of-the-art access networks. Furthermore, it shares the critical steps and details of the developments and deployment of these emergent technologies; which is very crucial particularly as telecommunications vendors and carriers are looking for cost-effective ultra-broadband last-mile access solutions to stay competitive in the post bubble era.

The book is written to provide a comprehensive overview of the major broadband access technologies and deployments involving internationally recognized authors and key players. Due to its scope and depth, the proposed book is able to fill an important gap of today 's available literature.

Resource Management for Distributed Multimedia Systems addresses the problems and challenges of handling several continuous- media data streams in networked multimedia environments. The work demonstrates how resource management mechanisms can be integrated into a stream handling system. The resulting system includes functions for Quality of Service (QoS) calculations, scheduling, determination of resource requirements, and methods to reduce resource requirements. The work explains the following: a suitable system architecture and resource management scheme that allows for the provision and enforcement of QoS guarantee, resource scheduling mechanisms for CPU and buffer space, mechanisms to measure and collect resource requirements, methods to extend resource management to future scenarios by allowing the reservation of resources in advance and offering sealing mechanisms. . Resource Management for Distributed Multimedia Systems is a comprehensive view of resource management for a broad technical audience that includes computer scientists and engineers involved in developing multimedia applications.

In these exciting times of quotidianly progressing developments in communication techniques, where more than ever in the history of a technological progress, society's reliance on communication networks for medicine, education, data transfer, commerce, and many other endeavours dominates the human's everyday life, the optical networks are certainly one of the most promising and challenging networking options. Since their commercial arrival in the nineties, they have fundamentally changed the way of dealing with traffic engineering by removing bandwidth bottlenecks and eliminating delays. Today, after the revolutionary bandwidth expansion, the networking functionality migrates more and more to the optical layer, and the need to establish fast wavelength circuits and capacity-on-demand for the higher-layer networks, in particular data networks based on Internet Protocol (IP), has become one of the central networking issues for the new century. The unifying trends toward configurable all-optical network infrastructure open up a wide range of new network engineering and design choices dealing with networks' interoperability and common platforms for control and management. The Fifth Working Conference on Optical Network Design and Modelling, held in the Austrian capital Vienna, February 5-7, 2001, aims at presenting the most recent progress in optical communication techniques, new technologies, standardisation process, emerging markets and carriers. A short look at the Table of Contents of this book tells us, in fact, that this year's conference program reflects the current state of the art precisely.

This book comprehensively reviews searchable encryption, which represents a series of research developments that directly enable search functionality over encrypted data. The book majorly covers: 1) the design and implementation of encrypted search algorithms, data structures, and systems that facilitate various forms of search over always-encrypted databases; 2) different threat models, assumptions, and the related security guarantees, when using searchable encryption in the real-world settings; and 3) latest efforts in building full-fledged encrypted database systems that draw insights from searchable encryption constructions. The book fits in the timely context, where the necessity of safeguarding important and sensitive data has been globally recognized. Traditional security measures, such as storing data behind network firewalls and layers of access control mechanisms to keep attackers out, are no longer sufficient to cope with the expanding landscape of surging cyber threats. There is an urgent call to keep sensitive data always encrypted to protect the data at rest, in transit, and in use. Doing so guarantees data confidentiality for owners, even if the data is out of their hands, e.g., hosted at in-the-cloud databases. The daunting challenge is how to perform computation over encrypted data. As we unfold in this book, searchable encryption, as a specific line of research in this broadly defined area, has received tremendous advancements over the past decades. This book is majorly oriented toward senior undergraduates, graduate students, and researchers, who want to work in the field and need extensive coverage of encrypted database research. It also targets security practitioners who want to make well-informed deployment choices of the latest advancements in searchable encryption for their targeted applications. Hopefully, this book will be beneficial in both regards.

The recent rapid advances in wireless technologies have created a demand for high quality multimedia applications and services. These advanced multimedia applications give rise to a new set of challenges in providing Quality of Service (QoS) when delivering these services over wireless networks. The Handbook of Research on Wireless Multimedia: Quality of Service and Solutions highlights and discusses the underlying QoS issues that arise in the delivery of real-time multimedia services over wireless networks. This cutting-edge book presents state-of-the-art solutions from leading researchers active in the field to address the QoS issues for different wireless multimedia applications.

Intelligent Broadband Multimedia Networks is a non-mathematical, but highly systems oriented, coverage of modern intelligent information networks. This volume focuses on the convergence of computers and communications technologies. Most of the concepts that are generic to all intelligent networks, and their microscopic and macroscopic functions, are presented. This book includes specific architectures that can be used by network designers and planners, telecommunications managers, computer scientists, and telecommunications professionals. The breadth of this coverage and the systems orientation of this work make the text suitable for use in advanced level courses on intelligent communications networks. The material in this volume ranges from defining intelligent networks to more specific coverage of educational, medical, and knowledge-based networks. Each of the 20 chapters address issues that can help make the transition from computer design, to the underlying concepts of modern telecommunications systems, to considerations necessary for the implementation of intelligent network services. Special and timely coverage of emerging technologies, such as HDSL, ADSL, BISDN, wireless, broadband access, ATM, and other topics, are given expanded treatment. The authors have included design methodologies for installing intelligence into almost any communications systems, and procedures for using such intelligence according to the type of function expected from these networks. Unique features of the book are: a 64-page glossary of key terms (with expanded explanations) used in the field, a 23-page index that makes it easy to search for important information, running headers on each page to help the busy professional use the book as a reference/design tool, complete references including additional reading for more detailed information, and accurate and concise information to help telecommunications professionals understand the intricacies of the field.

The Cloud Computing and Services Science book comprises a collection of the best papers presented at the International Conference on Cloud Computing and Services Science (CLOSER), which was held in The Netherlands in May 2011. In netting papers from the conference researchers and experts from all over the world explore a wide-ranging variety of the emerging Cloud Computing platforms, models, applications and enabling technologies. Further, in several papers the authors exemplify essential links to Services Science as service development abstraction, service innovation, and service engineering, acknowledging the service-orientation in most current IT-driven structures in the Cloud.

The Cloud Computing and Services Science book is organized around important dimensions of technology trends in the domain of cloud computing in relation to a broad scientific understanding of modern services emerging from services science. The papers of this book are inspired by scholarly and practical work on the latest advances related to cloud infrastructure, operations, security, services, and management through the global network. This book includes several features that will be helpful, interesting, and inspirational to students, researchers as well as practitioners. Professionals and decision makers working in this field will also benefit from this book

This book shows in detail how to build enterprise-level secure, redundant, and highly scalable services from scratch on top of the open source Linux operating system, suitable for small companies as well as big universities. The core architecture presented is based on Kerberos, LDAP, AFS, and Samba. Coverage shows how to integrate web, message related, data base and other services with this backbone. This architecture provides a Single-Sign-On solution for different client platforms and can also be employed for clustering. Although it is implemented with Debian GNU/Linux, the content can be applied to other UNIX flavors.

karmano hy api boddhavyam boddhavyam ca vikarmanah akarmanas ca boddhavyam gahana karmano gatih The intricacies of action are very hard to understand. Therefore one should know properly what action is, what forbidden action is, and what inaction is. The Bhagvad Gita (4.17) This book is the outcome of the research contribution of Hanane Fathi towards her Ph.D. studies jointly with Shyam S. Chakraborty and Ramjee Prasad as - pervisors. To the best of the authors' knowledge, this is a ?rst book on voice over Internet protocol (VoIP) covering such a broad perspective as illustrated in Figure P.1. This book is a new, forward-looking resource that explores the present and future trends of VoIP in the wireless heterogeneous networks. This book also provides the discovery path that these network infrastructures are following from a perspective of synergies with the present systems and how they will pave the way for future systems. This book is intended for everyone in the ?eld of wireless information and multimedia communications. It provides different levels of material suitable for managers, researchers, network providers, and graduate students. We hope that all readers will experience the bene?ts and power of this knowledge. We have tried our best to make each chapter comprehensive and we cannot claim that this book is without errors. Any remarks to improve the text and correct the errors would be highly appreciated.

This book presents cutting-edge work on real-time modelling and processing, a highly active research field in both the research and industrial domains. Going beyond conventional real-time systems, major efforts are required to develop accurate and computational efficient real-time modelling algorithms and design automation tools that reflect the technological advances in high-speed and ultra-low-power transceiver communication architectures based on nanoscale devices. The book addresses basic and more advanced topics, such as I/O buffer circuits for ensuring reliable chip-to-chip communication, I/O buffer behavioural modelling, multiport empirical models for memory interfaces, compact behavioural modelling for memristive devices, and resource reservation modelling for distributed embedded systems. The respective chapters detail new research findings, new models, algorithms, implementations and simulations of the above-mentioned topics. As such, the book will help both graduate students and researchers understand the latest research into real-time modelling and processing.

Understand the CCPA (California Consumer Privacy Act) and how to implement strategies to comply with this privacy regulation. Established in June 2018, the CCPA was created to remedy the lack of comprehensive privacy regulation in the state of California. When it comes into effect on January 1, 2020, the CCPA will give California residents the right to: Learn what personal data a business has collected about them Understand who this data has been disclosed to Find out whether their personal data has been sold to third parties, and who these third parties are Opt-out of such data transactions, or request that the data be deleted. Many organizations that do business in the state of California must align to the provisions of the CCPA. Much like the EU's GDPR (General Data Protection Regulation), businesses that fail to comply with the CCPA will face economic penalties. Prepare your business for CCPA compliance with our implementation guide that: Provides the reader with a comprehensive understanding of the legislation by explaining key terms Explains how a business can implement strategies to comply with the CCPA Discusses potential developments of the CCPA to further aid compliance Your guide to understanding the CCPA and how you can implement a strategy to comply with this legislation - buy this book today to get the guidance you need! About the author Preston Bukaty is an attorney and consultant. He specializes in data privacy GRC projects, from data inventory audits to gap analyses, contract management, and remediation planning. His compliance background and experience operationalizing compliance in a variety of industries give him a strong understanding of the legal issues presented by international regulatory frameworks. Having conducted more than 3,000 data mapping audits, he also understands the practical realities of project management in operationalizing compliance initiatives. Preston's legal experience and enthusiasm for technology make him uniquely suited to understanding the business impact of privacy regulations such as the GDPR and the CCPA. He has advised more than 250 organizations engaged in businesses as varied as SaaS platforms, mobile geolocation applications, GNSS/telematics tools, financial institutions, fleet management software, architectural/engineering design systems, and web hosting. He also teaches certification courses on GDPR compliance and ISO 27001 implementation, and writes on data privacy law topics. Preston lives in Denver, Colorado. Prior to working as a data privacy consultant, he worked for an international GPS software company, advising business areas on compliance issues across 140 countries. Preston holds a juris doctorate from the University of Kansas School of Law, along with a basketball signed by Hall of Fame coach Bill Self.

The five-volume set IFIP AICT 630, 631, 632, 633, and 634 constitutes the refereed proceedings of the International IFIP WG 5.7 Conference on Advances in Production Management Systems, APMS 2021, held in Nantes, France, in September 2021.*The 378 papers presented were carefully reviewed and selected from 529 submissions. They discuss artificial intelligence techniques, decision aid and new and renewed paradigms for sustainable and resilient production systems at four-wall factory and value chain levels. The papers are organized in the following topical sections: Part I: artificial intelligence based optimization techniques for demand-driven manufacturing; hybrid approaches for production planning and scheduling; intelligent systems for manufacturing planning and control in the industry 4.0; learning and robust decision support systems for agile manufacturing environments; low-code and model-driven engineering for production system; meta-heuristics and optimization techniques for energy-oriented manufacturing systems; metaheuristics for production systems; modern analytics and new AI-based smart techniques for replenishment and production planning under uncertainty; system identification for manufacturing control applications; and the future of lean thinking and practice Part II: digital transformation of SME manufacturers: the crucial role of standard; digital transformations towards supply chain resiliency; engineering of smart-product-service-systems of the future; lean and Six Sigma in services healthcare; new trends and challenges in reconfigurable, flexible or agile production system; production management in food supply chains; and sustainability in production planning and lot-sizing Part III: autonomous robots in delivery logistics; digital transformation approaches in production management; finance-driven supply chain; gastronomic service system design; modern scheduling and applications in industry 4.0; recent advances in sustainable manufacturing; regular session: green production and circularity concepts; regular session: improvement models and methods for green and innovative systems; regular session: supply chain and routing management; regular session: robotics and human aspects; regular session: classification and data management methods; smart supply chain and production in society 5.0 era; and supply chain risk management under coronavirus Part IV: AI for resilience in global supply chain networks in the context of pandemic disruptions; blockchain in the operations and supply chain management; data-based services as key enablers for smart products, manufacturing and assembly; data-driven methods for supply chain optimization; digital twins based on systems engineering and semantic modeling; digital twins in companies first developments and future challenges; human-centered artificial intelligence in smart manufacturing for the operator 4.0; operations management in engineer-to-order manufacturing; product and asset life cycle management for smart and sustainable manufacturing systems; robotics technologies for control, smart manufacturing and logistics; serious games analytics: improving games and learning support; smart and sustainable production and supply chains; smart methods and techniques for sustainable supply chain management; the new digital lean manufacturing paradigm; and the role of emerging technologies in disaster relief operations: lessons from COVID-19 Part V: data-driven platforms and applications in production and logistics: digital twins and AI for sustainability; regular session: new approaches for routing problem solving; regular session: improvement of design and operation of manufacturing systems; regular session: crossdock and transportation issues; regular session: maintenance improvement and lifecycle management; regular session: additive manufacturing and mass customization; regular session: frameworks and conceptual modelling for systems and services efficiency; regular session: optimization of production and transportation systems; regular session: optimization of supply chain agility and reconfigurability; regular session: advanced modelling approaches; regular session: simulation and optimization of systems performances; regular session: AI-based approaches for quality and performance improvement of production systems; and regular session: risk and performance management of supply chains *The conference was held online.

This volume contains revised and extended research articles written by prominent researchers participating in the ICF4C 2011 conference. 2011 International Conference on Future Communication, Computing, Control and Management (ICF4C 2011) has been held on December 16-17, 2011, Phuket, Thailand. Topics covered include intelligent computing, network management, wireless networks, telecommunication, power engineering, control engineering, Signal and Image Processing, Machine Learning, Control Systems and Applications, The book will offer the states of arts of tremendous advances in Computing, Communication, Control, and Management and also serve as an excellent reference work for researchers and graduate students working on Computing, Communication, Control, and Management Research.

This textbook was written from the perspective of someone who began his software security career in 2005, long before the industry began focusing on it. This is an excellent perspective for students who want to learn about securing application development. After having made all the rookie mistakes, the author realized that software security is a human factors issue rather than a technical or process issue alone. Throwing technology into an environment that expects people to deal with it but failing to prepare them technically and psychologically with the knowledge and skills needed is a certain recipe for bad results. Practical Security for Agile and DevOps is a collection of best practices and effective implementation recommendations that are proven to work. The text leaves the boring details of software security theory out of the discussion as much as possible to concentrate on practical applied software security that is useful to professionals. It is as much a book for students' own benefit as it is for the benefit of their academic careers and organizations. Professionals who are skilled in secure and resilient software development and related tasks are in tremendous demand. This demand will increase exponentially for the foreseeable future. As students integrate the text's best practices into their daily duties, their value increases to their companies, management, community, and industry. The textbook was written for the following readers: Students in higher education programs in business or engineering disciplines AppSec architects and program managers in information security organizations Enterprise architecture teams with a focus on application development Scrum Teams including: Scrum Masters Engineers/developers Analysts Architects Testers DevOps teams Product owners and their management Project managers Application security auditors Agile coaches and trainers Instructors and trainers in academia and private organizations

This book provides a comprehensive introduction to hardware security, from specification to implementation. Applications discussed include embedded systems ranging from small RFID tags to satellites orbiting the earth. The authors describe a design and synthesis flow, which will transform a given circuit into a secure design incorporating counter-measures against fault attacks. In order to address the conflict between testability and security, the authors describe innovative design-for-testability (DFT) computer-aided design (CAD) tools that support security challenges, engineered for compliance with existing, commercial tools. Secure protocols are discussed, which protect access to necessary test infrastructures and enable the design of secure access controllers.

Processes and Foundations for Virtual Organizations contains selected articles from PRO-VE'03, the Fourth Working Conference on Virtual Enterprises, which was sponsored by the International Federation for Information Processing (IFIP) and held in Lugano, Switzerland in October 2003. This fourth edition includes a rich set of papers revealing the progress and achievements in the main current focus areas:

-VO breeding environments;
-Formation of collaborative networked organizations;
-Ontologies and knowledge management;
-Process models and interoperability;
-Infrastructures;
-Multi-agent approaches. In spite of many valid contributions in these areas, many research challenges remain. This is clearly stated in a number of papers suggesting a new research agenda and strategic research roadmaps for advanced virtual organizations.
With the selected papers included in this book, PRO-VE pursues its double mission as a forum for presentation and discussion of achievements as well as a place to discuss and suggest new directions and research strategies.

This volume presents proceedings from the 19th IFIP World Computer Congress in Santiago, Chile. The proceedings of the World Computer Congress are a product of the gathering of 2,000 delegates from more than 70 countries to discuss a myriad of topics in the ICT domain. Of particular note, this marks the first time that a World Computer Congress has been held in a Latin American country.

Topics in this series include:

• The 4th International Conference on Theoretical Computer Science
• Education for the 21st Century- Impact of ICT and Digital Resources
• Mobile and Wireless Communication Networks
• Ad-Hoc Networking
• Network Control and Engineering for QoS, Security, and Mobility
• The Past and Future of Information Systems: 1976-2006 and Beyond
• History of Computing and Education
• Biologically Inspired Cooperative Computing
• Artificial Intelligence in Theory and Practice
• Applications in Artificial Intelligence
• Advanced Software Engineering: Expanding the Frontiers of Software

For a complete list of the more than 300 titles in the IFIP Series, visit springer.com.

For more information about IFIP, please visit ifip.org.

Social networks provide a powerful abstraction of the structure and dynamics of diverse kinds of people or people-to-technology interaction. Web 2.0 has enabled a new generation of web-based communities, social networks, and folksonomies to facilitate collaboration among different communities.

This unique text/reference compares and contrasts the ethological approach to social behavior in animals with web-based evidence of social interaction, perceptual learning, information granulation, the behavior of humans and affinities between web-based social networks. An international team of leading experts present the latest advances of various topics in intelligent-social-networks and illustrates how organizations can gain competitive advantages by applying the different emergent techniques in real-world scenarios. The work incorporates experience reports, survey articles, and intelligence techniques and theories with specific network technology problems.

Topics and Features: Provides an overview social network tools, and explores methods for discovering key players in social networks, designing self-organizing search systems, and clustering blog sites, surveys techniques for exploratory analysis and text mining of social networks, approaches to tracking online community interaction, and examines how the topological features of a system affects the flow of information, reviews the models of network evolution, covering scientific co-citation networks, nature-inspired frameworks, latent social networks in e-Learning systems, and compound communities, examines the relationship between the intent of web pages, their architecture and the communities who take part in their usage and creation, discusses team selection based on members' social context, presents social network applications, including music recommendation and face recognition in photographs, explores the use of social networks in web services that focus on the discovery stage in the life cycle of these web services.

This useful and comprehensive volume will be indispensible to senior undergraduate and postgraduate students taking courses in Social Intelligence, as well as to researchers, developers, and postgraduates interested in intelligent-social-networks research and related areas.

This book focuses on privacy and security concerns in big data and differentiates between privacy and security and privacy requirements in big data. It focuses on the results obtained after applying a systematic mapping study and implementation of security in the big data for utilizing in business under the establishment of "Business Intelligence". The chapters start with the definition of big data, discussions why security is used in business infrastructure and how the security can be improved. In this book, some of the data security and data protection techniques are focused and it presents the challenges and suggestions to meet the requirements of computing, communication and storage capabilities for data mining and analytics applications with large aggregate data in business.

The insertion of communication networks in feedback control loops complicates analysis and synthesis of cyber-physical systems (CPSs), and network-induced uncertainties may degrade system control performance. Thus, this book researches networked delay compensation and event-triggered control approaches for a series of CPSs subject to network-induced uncertainties. The authors begin with an introduction to the concepts and challenges of CPSs, followed by an overview of networked control approaches and event-triggered control strategies in CPSs. Then, networked delay compensation and event-triggered control approaches are proposed for CPSs with network communication delay, data dropout, signal quantization, and event-triggered communication. More specifically, networked delay compensation approaches are proposed for linear/nonlinear networked controlled plants with time-varying and random network communication delays and data dropouts. To reduce computational burden and network communication loads in CPSs, event-triggered control, self-triggered control, co-design of event-triggered control and quantized control techniques, and event-triggered disturbance rejection control approaches are also presented. This book is an essential text for researchers and engineers interested in cybersecurity, networked control, and CPSs. It would also prove useful for graduate students in the fields of science, engineering, and computer science.

This open access book discusses the most modern approach to auditing complex digital systems and technologies. It combines proven auditing approaches, advanced programming techniques and complex application areas, and covers the latest findings on theory and practice in this rapidly developing field. Especially for those who want to learn more about novel approaches to testing complex information systems and related technologies, such as blockchain and self-learning systems, the book will be a valuable resource. It is aimed at students and practitioners who are interested in contemporary technology and managerial implications.

As organizations today are linking their systems across enterprise-wide networks and VPNs as well as increasing their exposure to customers, competitors, browsers and hackers on the Internet, it becomes increasingly imperative for Web professionals to be trained in techniques for effectively protecting their sites from internal and external threats. Each connection magnifies the vulnerability to attack. With the increased connectivity to the Internet and the wide availability of automated cracking tools, organizations can no longer simply rely on operating system security to protect their valuable corporate data. Furthermore, the exploding use of Web technologies for corporate intranets and Internet sites has escalated security risks to corporate data and information systems.

Practical Internet Security reveals how the Internet is paving the way for secure communications within organizations and on the public Internet. This book provides the fundamental knowledge needed to analyze risks to a system and to implement a security policy that protects information assets from potential intrusion, damage, or theft. It provides dozens of real-life scenarios and examples, as well as hands-on instruction in securing Web communications and sites. You will learn the common vulnerabilities of Web sites; as well as, how to carry out secure communications across unsecured networks. All system administrators and IT security managers will find this book an essential practical resource.

An oft-repeated adage among telecommunication providers goes, "There are ve things that matter: reliability, reliability, reliability, time to market, and cost. If you can't do all ve, at least do the rst three. " Yet, designing and operating reliable networks and services is a Herculean task. Building truly reliable components is unacceptably expensive, forcing us to c- struct reliable systems out of unreliable components. The resulting systems are inherently complex, consisting of many different kinds of components running a variety of different protocols that interact in subtle ways. Inter-networkssuch as the Internet span multiple regions of administrative control, from campus and cor- rate networks to Internet Service Providers, making good end-to-end performance a shared responsibility borne by sometimes uncooperative parties. Moreover, these networks consist not only of routers, but also lower-layer devices such as optical switches and higher-layer components such as rewalls and proxies. And, these components are highly con gurable, leaving ample room for operator error and buggy software. As if that were not dif cult enough, end users understandably care about the performance of their higher-level applications, which has a complicated relationship with the behavior of the underlying network. Despite these challenges, researchers and practitioners alike have made trem- dous strides in improving the reliability of modern networks and services.