AS-Path Prepending: There is no rose without a thorn

Inbound traffic engineering (ITE) - -the process of announcing routes to, e.g., maximize revenue or minimize congestion - -is an essential task for Autonomous Systems (ASes). AS Path Prepending (ASPP) is an easy to use and well-known ITE technique that routing manuals show as one of the first alternatives to influence other ASes' routing decisions. We observe that origin ASes currently prepend more than 25% of all IPv4 prefixes. ASPP consists of inflating the BGP AS path. Since the length of the AS path is the second tie-breaker in the BGP best path selection, ASPP can steer traffic to other routes. Despite being simple and easy to use, the appreciation of ASPP among operators and researchers is diverse. Some have questioned its need, effectiveness, and predictability, as well as voiced security concerns. Motivated by these mixed views, we revisit ASPP. Our longitudinal study shows that ASes widely deploy ASPP, and its utilization has slightly increased despite public statements against it. We surprisingly spot roughly 6k ASes originating at least one prefix with prepends that achieve no ITE goal. With active measurements, we show that ASPP effectiveness as an ITE tool depends on the AS location and the number of available upstreams; that ASPP security implications are practical; identify that more than 18% of the prepended prefixes contain unnecessary prepends that achieve no apparent goal other than amplifying existing routing security risks. We validate our findings in interviews with 20 network operators

A FRAMEWORK FOR DEFENDING AGAINST PREFIX HIJACK ATTACKS

Border Gateway Protocol (BGP) prefix hijacking is a serious problem in the Internet today. Although there are several services being offered to detect a prefix hijack, there has been little work done to prevent a hijack or to continue providing network service during a prefix hijack attack. This thesis proposes a novel framework to provide defense against prefix hijacking which can be offered as a service by Content Distribution Networks and large Internet Service Providers. Our experiments revealed that the hijack success rate reduced from 90.36% to 30.53% at Tier 2, 84.65% to 10.98% at Tier 3 and 82.45% to 8.39% at Tier 4 using Autonomous Systems (ASs) of Akamai as Hijack Prevention Service Provider. We also observed that 70% of the data captured by Hijack Prevention Service Provider (HPSP) can be routed back to Victim. However if we use tunneling, i.e. trying to route data to neighbors of Victims which in turn sends the traffic to Victims, we observed that data can be routed to Victim 98.09% of the time. Also, the cost of such redirection is minimal, since the average increase in path length was observed to be 2.07 AS hops

Improving the Accuracy of the Internet Cartography

As the global Internet expands to satisfy the demands of the ever-increasing connected population, profound changes are occurring in its interconnection structure. The pervasive growth of IXPs and CDNs, two initially independent but synergistic infrastructure sectors, have contributed to the gradual flattening of the Internet’s inter-domain hierarchy with primary routing paths shifting from backbone networks to peripheral peering links. At the same time the IPv6 deployment has taken off due to the depletion of unallocated IPv4 addresses. These fundamental changes in Internet dynamics has obvious implications for network engineering and operations, which can be benefited by accurate topology maps to understand the properties of this critical infrastructure. This thesis presents a set of new measurement techniques and inference algorithms to construct a new type of semantically rich Internet map, and improve the state of the art in Internet cartography. The author first develops a methodology to extract large-scale validation data from the Communities BGP attribute, which encodes rich routing meta-data on BGP messages. Based on this better-informed dataset the author proceeds to analyse popular assumptions about inter-domain routing policies and devise a more accurate model to describe inter-AS business relationships. Accordingly, the thesis proposes a new relationship inference algorithm to accurately capture both simple and complex AS relationships across two dimensions: prefix type, and geographic location. Validation against three sources of ground-truth data reveals that the proposed algorithm achieves a near-perfect accuracy. However, any inference approach is constrained by the inability of the existing topology data sources to provide a complete view of the inter-domain topology. To limit the topology incompleteness problem the author augments traditional BGP data with routing policy data obtained directly from IXPs to discover massive peering meshes which have thus far been largely invisible

Спосіб підвищення ефективності вибору шляху при груповій маршрутизації

Актуальність теми. Кожен день все більше використовується мережа Інтернет для обміну інформацією, що в значній мірі є можливим завдяки функціонуванню протоколу BGP (Border Gateway Protocol), як єдиного протоколу зовнішньої групової маршрутизації між окремими мережами. Через швидкий приріст кількості користувачів та збільшення об’ємів інформації, що передається, знов і знов піднімається питання про підвищення ефективності та оптимізацію пошуку шляху для передачі даних при такій маршрутизації. Мета роботи: підвищення ефективності пошуку шляху передачі даних при груповій маршрутизації та розробка й оптимізація способу перерозподілу навантаження каналів зв’язку з використанням програмного контролера. Для досягнення поставленої мети в роботі вирішуються наступні завдання. 1. Аналіз існуючих методик покращення критеріїв пошуку ефективного шляху при груповій маршрутизації. 2. Дослідження проблеми пошуку оптимального шляху при груповій маршрутизації. 3. Розробка модифікованої імітаційної моделі. 4. Розробка способу підвищення ефективності пошуку шляху при груповій маршрутизації з використанням програмного контролера, що базується на контролі і перерозподілі навантаження каналів зв’язку. Об’єктом дослідження є процес та принципи функціонування протоколу групової маршрутизації BGP. Предметом дослідження є спосіб підвищення ефективності пошуку шляху при груповій маршрутизації, що базується на контролі і перерозподілі навантаження каналів зв’язку. Методи дослідження. В роботі використовуються методи оптимізації, методи моделювання комп’ютерних мереж. Наукова новизна одержаних результатів полягає в наступному: 1. Проаналізовано основні методики покращення критеріїв пошуку ефективного шляху при груповій маршрутизації. 2. Запропоновано спосіб з використанням програмного контролеру для підвищення ефективності пошуку маршруту через примусовий перерозподіл трафіку за наявними посиланнями на основі використання або затримки посилань. 3. Розроблена модифікована імітаційна модель для проведення безпечних тестувань та збору тестових даних. Практична цінність одержаних результатів полягає в тому, що запропонований спосіб підвищує показники ефективності пошуку шляху при груповій маршрутизації за часовим критерієм, що дозволяє отримати виграш у середньому до 3,5% у порівнянні з вже існуючими аналогами і при цьому він не має впливу на безпеку функціонування мережі та протоколу, з якими працює. Апробація роботи. Основні положення і результати роботи були представлені та обговорювались на XIV всеукраїнській науково методичній конференції «Проблеми охорони праці, промислової та цивільної безпеки 2018», XII науковій конференції молодих вчених «Прикладна математика та комп’ютинг» ПМК-2019 (Київ, 13-15 листопада 2019 р.). Публікації. За результатами магістерської дисертації було опубліковано 3 наукові роботи, з них 1 стаття у науковому фаховому виданні України (у виданні, що реферується наукометричною базою) та 2 тези доповідей. Науковий журнал «Комп’ютерні-інтегровані технології: освіта, наука, виробництво» – Луцьк, 2020. Випуск №39. Структура та обсяг роботи. Магістерська дисертація складається з вступу, трьох розділів, висновків та додатків. У вступі надано загальну характеристику проблематики ефективності групової маршрутизації, сформульовано мету дослідження, показано практичну цінність роботи. У першому розділі надано детальне обґрунтування актуальності напрямку досліджень, виконано оцінку поточного стану в даній сфері, представлено теоретичний огляд особливостей функціонування BGP. У другому розділі проаналізовано критерії оптимізації пошуку шляху, досліджено методи покращення цих критеріїв; розглянуто вимоги до імітаційної моделі, для тестування способу підвищення ефективності пошуку шляху. У третьому розділі розроблено та описано програмний контролер для підвищення ефективності шляху при груповій маршрутизації, представлена порівняльна характеристика запропонованого способу з вже існуючими. У висновках проаналізовано отримані результати роботи. Робота виконана на 81 аркуші, містить 3 додатки та посилання на список використаних літературних джерел з 37 найменувань. У роботі наведено 21 рисунків та 4 таблиці.Actuality of the theme. Every day, the Internet is increasingly used to exchange information, which is largely possible due to the functioning of the BGP protocol (Border Gateway Protocol), as a single protocol for external group routing between individual networks. Due to the rapid increase in the number of users and the increase in the amount of information transmitted, the question of improving the efficiency and optimization of finding a way to transmit data with such routing is raised again and again. The goal of the work: increase the efficiency of data path retrieval in group routing and develop and optimize the method of load redistribution of communication channels using a software controller. To achieve this goal, the following tasks are solved in the work. 1. Analysis of existing methods for improving the criteria for finding an effective way for group routing. 2. Research of a problem of search of an optimum way at group routing. 3. Development of a modified simulation model. 4. Development of a method to increase the efficiency of path finding in group routing using a software controller based on control and redistribution of communication channels. The object of the research is the process and principles of operation of the BGP group routing protocol. The subject of the research is way to increase the efficiency of path finding in group routing, based on the control and redistribution of communication channels. Research methods. Optimization methods, network modeling methods are used in the work. The scientific novelty of the obtained results is as follows: 1. The main methods of improving the criteria for finding an effective way for group routing are analyzed. 2. The method using a software controller to increase the efficiency of route search through forced redistribution of traffic on existing links based on the use or delay of links is proposed. 3. Developed a modified simulation model for safe testing and collection of test data. The practical value of the obtained results is that the proposed method increases the efficiency of finding a path with group routing by time criterion, which allows you to gain an average of up to 3.5% compared to existing counterparts and it does not affect the safety of operation the network and protocol it works with. Approbation of work. The main provisions and results of the work were presented and discussed at the XIV All-Ukrainian scientific-methodical conference "Problems of labor protection, industrial and civil safety 2018", XII scientific conference of young scientists "Applied Mathematics and Computing" PMK-2019 (Kyiv, 13-15 November 2019). Publications. According to the results of the master's dissertation, 3 scientific works were published, including 1 article in the scientific professional publication of Ukraine (in the publication, which is referenced by the scientometric base) and 2 abstracts. Scientific journal "Computer-integrated technologies: education, science, production" - Lutsk, 2020. Issue №39.Structure and scope of work. The master's thesis consists of an introduction, three sections, conclusions and appendices. The introduction gives a general description of the problems of the efficiency of group routing, formulated the purpose of the study, shows the practical value of the work. The first section provides a detailed justification for the relevance of the research direction, assesses the current state of affairs in this field, presents a theoretical overview of the features of BGP functioning. In the second section the criteria of optimization of search of a way are analyzed, methods of improvement of these criteria are investigated; the requirements to the simulation model for testing the way to increase the efficiency of the path search are considered. The third section develops and describes a software controller to improve the efficiency of the path in group routing, presents a comparative characteristic of the proposed method with existing ones. The conclusions are analyzed the results of work. The work is done on 81 sheets, contains 3 attachments and a link to the list of used literary sources of 37 titles. The paper presents 21 figures and 4 tables

Meta-heuristic Solution Methods for Rich Vehicle Routing Problems

Le problème de tournées de véhicules (VRP), introduit par Dantzig and Ramser en 1959, est devenu l'un des problèmes les plus étudiés en recherche opérationnelle, et ce, en raison de son intérêt méthodologique et de ses retombées pratiques dans de nombreux domaines tels que le transport, la logistique, les télécommunications et la production. L'objectif général du VRP est d'optimiser l'utilisation des ressources de transport afin de répondre aux besoins des clients tout en respectant les contraintes découlant des exigences du contexte d’application. Les applications réelles du VRP doivent tenir compte d’une grande variété de contraintes et plus ces contraintes sont nombreuse, plus le problème est difficile à résoudre. Les VRPs qui tiennent compte de l’ensemble de ces contraintes rencontrées en pratique et qui se rapprochent des applications réelles forment la classe des problèmes ‘riches’ de tournées de véhicules. Résoudre ces problèmes de manière efficiente pose des défis considérables pour la communauté de chercheurs qui se penchent sur les VRPs. Cette thèse, composée de deux parties, explore certaines extensions du VRP vers ces problèmes. La première partie de cette thèse porte sur le VRP périodique avec des contraintes de fenêtres de temps (PVRPTW). Celui-ci est une extension du VRP classique avec fenêtres de temps (VRPTW) puisqu’il considère un horizon de planification de plusieurs jours pendant lesquels les clients n'ont généralement pas besoin d’être desservi à tous les jours, mais plutôt peuvent être visités selon un certain nombre de combinaisons possibles de jours de livraison. Cette généralisation étend l'éventail d'applications de ce problème à diverses activités de distributions commerciales, telle la collecte des déchets, le balayage des rues, la distribution de produits alimentaires, la livraison du courrier, etc. La principale contribution scientifique de la première partie de cette thèse est le développement d'une méta-heuristique hybride dans la quelle un ensemble de procédures de recherche locales et de méta-heuristiques basées sur les principes de voisinages coopèrent avec un algorithme génétique afin d’améliorer la qualité des solutions et de promouvoir la diversité de la population. Les résultats obtenus montrent que la méthode proposée est très performante et donne de nouvelles meilleures solutions pour certains grands exemplaires du problème. La deuxième partie de cette étude a pour but de présenter, modéliser et résoudre deux problèmes riches de tournées de véhicules, qui sont des extensions du VRPTW en ce sens qu'ils incluent des demandes dépendantes du temps de ramassage et de livraison avec des restrictions au niveau de la synchronization temporelle. Ces problèmes sont connus respectivement sous le nom de Time-dependent Multi-zone Multi-Trip Vehicle Routing Problem with Time Windows (TMZT-VRPTW) et de Multi-zone Mult-Trip Pickup and Delivery Problem with Time Windows and Synchronization (MZT-PDTWS). Ces deux problèmes proviennent de la planification des opérations de systèmes logistiques urbains à deux niveaux. La difficulté de ces problèmes réside dans la manipulation de deux ensembles entrelacés de décisions: la composante des tournées de véhicules qui vise à déterminer les séquences de clients visités par chaque véhicule, et la composante de planification qui vise à faciliter l'arrivée des véhicules selon des restrictions au niveau de la synchronisation temporelle. Auparavant, ces questions ont été abordées séparément. La combinaison de ces types de décisions dans une seule formulation mathématique et dans une même méthode de résolution devrait donc donner de meilleurs résultats que de considérer ces décisions séparément. Dans cette étude, nous proposons des solutions heuristiques qui tiennent compte de ces deux types de décisions simultanément, et ce, d'une manière complète et efficace. Les résultats de tests expérimentaux confirment la performance de la méthode proposée lorsqu’on la compare aux autres méthodes présentées dans la littérature. En effet, la méthode développée propose des solutions nécessitant moins de véhicules et engendrant de moindres frais de déplacement pour effectuer efficacement la même quantité de travail. Dans le contexte des systèmes logistiques urbains, nos résultats impliquent une réduction de la présence de véhicules dans les rues de la ville et, par conséquent, de leur impact négatif sur la congestion et sur l’environnement.For more than half of century, since the paper of Dantzig and Ramser (1959) was introduced, the Vehicle Routing Problem (VRP) has been one of the most extensively studied problems in operations research due to its methodological interest and practical relevance in many fields such as transportation, logistics, telecommunications, and production. The general goal of the VRP is to optimize the use of transportation resources to service customers with respect to side-constraints deriving from real-world applications. The practical applications of the VRP may have a variety of constraints, and obviously, the larger the set of constraints that need to be considered, i.e., corresponding to `richer' VRPs, the more difficult the task of problem solving. The needs to study closer representations of actual applications and methodologies producing high-quality solutions quickly to larger-sized application problems have increased steadily, providing significant challenges for the VRP research community. This dissertation explores these extensional issues of the VRP. The first part of the dissertation addresses the Periodic Vehicle Routing Problem with Time Windows (PVRPTW) which generalizes the classical Vehicle Routing Problem with Time Windows (VRPTW) by extending the planning horizon to several days where customers generally do not require delivery on every day, but rather according to one of a limited number of possible combinations of visit days. This generalization extends the scope of applications to many commercial distribution activities such as waste collection, street sweeping, grocery distribution, mail delivery, etc. The major contribution of this part is the development of a population-based hybrid meta-heuristic in which a set of local search procedures and neighborhood-based meta-heuristics cooperate with the genetic algorithm population evolution mechanism to enhance the solution quality as well as to promote diversity of the genetic algorithm population. The results show that the proposed methodology is highly competitive, providing new best solutions in some large instances. The second part of the dissertation aims to present, model and solve two rich vehicle routing problems which further extend the VRPTW with time-dependent demands of pickup and delivery, and hard time synchronization restrictions. They are called Time-dependent Multi-zone Multi-Trip Vehicle Routing Problem with Time Windows (TMZT-VRPTW), and Multi-zone Mult-Trip Pickup and Delivery Problem with Time Windows and Synchronization (MZT-PDTWS), respectively. These two problems originate from planning the operations of two-tiered City Logistics systems. The difficulty of these problems lies in handling two intertwined sets of decisions: the routing component which aims to determine the sequences of customers visited by each vehicle, and the scheduling component which consists in planning arrivals of vehicles at facilities within hard time synchronization restrictions. Previously, these issues have been addressed separately. Combining these decisions into one formulation and solution method should yield better results. In this dissertation we propose meta-heuristics that address the two decisions simultaneously, in a comprehensive and efficient way. Experiments confirm the good performance of the proposed methodology compared to the literature, providing system managers with solution requiring less vehicles and travel costs to perform efficiently the same amount of work. In the context of City Logistics systems, our results indicate a reduction in the presence of vehicles on the streets of the city and, thus, in their negative impact on congestion and environment

Air Traffic Management Abbreviation Compendium

As in all fields of work, an unmanageable number of abbreviations are used today in aviation for terms, definitions, commands, standards and technical descriptions. This applies in general to the areas of aeronautical communication, navigation and surveillance, cockpit and air traffic control working positions, passenger and cargo transport, and all other areas of flight planning, organization and guidance. In addition, many abbreviations are used more than once or have different meanings in different languages. In order to obtain an overview of the most common abbreviations used in air traffic management, organizations like EUROCONTROL, FAA, DWD and DLR have published lists of abbreviations in the past, which have also been enclosed in this document. In addition, abbreviations from some larger international projects related to aviation have been included to provide users with a directory as complete as possible. This means that the second edition of the Air Traffic Management Abbreviation Compendium includes now around 16,500 abbreviations and acronyms from the field of aviation

Department of Defense Dictionary of Military and Associated Terms

The Joint Publication 1-02, Department of Defense Dictionary of Military and Associated Terms sets forth standard US military and associated terminology to encompass the joint activity of the Armed Forces of the United States. These military and associated terms, together with their definitions, constitute approved Department of Defense (DOD) terminology for general use by all DOD components

Inter-AS Inbound Traffic Engineering via ASPP

Abstract — AS Path Prepending (ASPP) is a popular method for the inter-AS inbound traffic engineering, which is known to be more difficult than the outbound traffic engineering. Although the ASPP approach has been extensively practised by many ASes, it is surprising that there still lacks a systematic study of this approach and the basic understanding of its effectiveness. In this paper, we introduce the concept, applicability and potential instability problem of the ASPP approach. Some guidelines are given as the first step to study the method to avoid instability problem. Finally, we study the dynamic prepending behavior of ISPs and show a real-world pathologic case of prepending instability based on our measurement study of RouteViews data. Index Terms — ASPP, BGP, instability. I

International Comparative Analysis of COVID-19 Responses

Chapter 01. Introduction Chapter 02. The Evolution of COVID-19 and Policy Responses of Korea: Adaptation and Learning Perspectives Chapter 03. Japan’s Response to the COVID-19 Pandemic: A Cautious and Self-restraint-based Approach Chapter 04. Thailand’s Response to COVID-19 Chapter 05. Beyond Regime Types: Local Governance, Bureaucratic Coordination, and COVID-19 Responses in Vietnam Chapter 06. Aotearoa New Zealand’s Policy Responses to the COVID-19 Pandemic Chapter 07. COVID-19 Responses in Finland: Uneven, Fairly Effective, and Craving to Return to the Normal Chapter 08. Crisis Governance in a Multilevel System: German Public Administration Coping with the COVID-19 Pandemic Chapter 09. Sweden and the COVID-19 Crisis Chapter 10. Science, Uncertainty, and Partisanship: The United States’ Response to COVID-19 Chapter 11. Summary and Discussions for Policy Implication