Du fait de la croissance de la demande en ressources de calcul, les architectures de centres de données gagnent en taille et complexité.Dès lors, cette thèse prend du recul par rapport aux architectures réseaux traditionnelles, et montre que fournir des primitives génériques directement à la couche réseau permet d'améliorer l'utilisation des ressources, et de diminuer le trafic réseau et le surcoût administratif.Deux architectures réseaux récentes, Segment Routing (SR) et Bit-Indexed Explicit Replication (BIER), sont utilisées pour construire et analyser des protocoles de couche réseau, afin de fournir trois primitives: (1) mobilité des tâches, (2) distribution fiable de contenu, et (3) équilibre de charge.Premièrement, pour la mobilité des tâches, SR est utilisé pour fournir un service de migration de machine virtuelles sans perte.Cela ouvre l'opportunité d'étudier comment orchestrer le placement et la migration de tâches afin de (i) maximiser le débit inter-tâches, tout en (ii) maximisant le nombre de nouvelles tâches placées, mais (iii) minimisant le nombre de tâches migrées.Deuxièmement, pour la distribution fiable de contenu, BIER est utilisé pour fournir un protocole de multicast fiable, dans lequel les retransmissions de paquets perdus sont ciblés vers l'ensemble précis de destinations n'ayant pas reçu ce packet : ainsi, le surcoût de trafic est minimisé.Pour diminuer la charge sur la source, cette approche est étendue en rendant possible des retransmissions par des pairs locaux, utilisant SR afin de trouver un pair capable de retransmettre.Troisièmement, pour l'équilibre de charge, SR est utilisé pour distribuer des requêtes à travers plusieurs applications candidates, chacune prenant une décision locale pour accepter ou non ces requêtes, fournissant ainsi une meilleure équité de répartition comparé aux approches centralisées.La faisabilité d'une implémentation matérielle de cette approche est étudiée, et une solution (utilisant des canaux cachés pour transporter de façon invisible de l'information vers l'équilibreur) est implémentée pour une carte réseau programmable de dernière génération.Finalement, la possibilité de fournir de l'équilibrage automatique comme service réseau est étudiée : en faisant passer (avec SR) des requêtes à travers une chaîne fixée d'applications, l'équilibrage est initié par la dernière instance, selon son état local. / With the development of demand for computing resources, data center architectures are growing both in scale and in complexity.In this context, this thesis takes a step back as compared to traditional network approaches, and shows that providing generic primitives directly within the network layer is a great way to improve efficiency of resource usage, and decrease network traffic and management overhead.Using recently-introduced network architectures, Segment Routing (SR) and Bit-Indexed Explicit Replication (BIER), network layer protocols are designed and analyzed to provide three high-level functions: (1) task mobility, (2) reliable content distribution and (3) load-balancing.First, task mobility is achieved by using SR to provide a zero-loss virtual machine migration service.This then opens the opportunity for studying how to orchestrate task placement and migration while aiming at (i) maximizing the inter-task throughput, while (ii) maximizing the number of newly-placed tasks, but (iii) minimizing the number of tasks to be migrated.Second, reliable content distribution is achieved by using BIER to provide a reliable multicast protocol, in which retransmissions of lost packets are targeted towards the precise set of destinations having missed that packet, thus incurring a minimal traffic overhead.To decrease the load on the source link, this is then extended to enable retransmissions by local peers from the same group, with SR as a helper to find a suitable retransmission candidate.Third, load-balancing is achieved by way of using SR to distribute queries through several application candidates, each of which taking local decisions as to whether to accept those, thus achieving better fairness as compared to centralized approaches.The feasibility of hardware implementation of this approach is investigated, and a solution using covert channels to transparently convey information to the load-balancer is implemented for a state-of-the-art programmable network card.Finally, the possibility of providing autoscaling as a network service is investigated: by letting queries go through a fixed chain of applications using SR, autoscaling is triggered by the last instance, depending on its local state.

Disruption Tolerant Networking (DTN) is a network architecture that enables communication between devices in challenging environments that may never have a contemporaneous end-to-end path. Routing in DTN is challenging since every node decides autonomously, based on local information, which bundles should be forwarded when two devices have a contact opportunity (i.e., when they meet). Frequently, devices exchange locally and transitively collected information (properties) during contact opportunities to support their routing algorithms. In the context of Public Transport Networks (PTN), devices may be vehicles (e.g., tram, bus) or stations that use vehicular mobility as a data carrier. Vehicles in a PTN tend to move back and forth, creating repetitive patterns. We assumed that routing algorithms capable of exploring those characteristics would likely maximize the desired metric, e.g., increasing delivery probability (DP) or minimizing latency. In the event of unexpected mobility changes, routing algorithms that perform well under normal mobility may perform poorly during this period. In this case, property exchange can provide context awareness, supporting a device in choosing the right moment to adapt the routing algorithm or tuning it at runtime. However, mobility adaptation and adaptive parametrization were not investigated in the context of DTN for PTN. This thesis proposes an adaptive routing module that supports multiple routing algorithms chosen independently, per bundle, at runtime. Our literature research revealed that many adaptive algorithms had been proposed. Still, only a few provided routing adaptation, and those approaches have not been addressed in the context of PTNs. From an extensive review of property exchange in DTN, we classified properties that algorithms exchanged at runtime. Finally, we provided an overview of the current DTN frameworks, showing that at least one allows the choice of the routing algorithm independently; however, the high coupling between routing and information exchange precludes the usage of multiple routing algorithms concurrently in practice. Therefore, our novel approach decouples property exchange from the routing algorithm, i.e., exchanging a set of properties consistently during contact opportunities independently of the routing algorithm used. From the different classes identified in the literature research, resource class is the most suitable for PTN as exchanging its properties enables reproducing the most common routing algorithms and providing context-awareness. The history of contacts is stored together with information about devices resources' state during each contact opportunity and spread transitively in the network. Since this information is immutable, it incrementally allows every device to improve its understanding of network behavior over time. Another improvement in our approach is exchanging raw information as an ordered list of the instantaneous information about the device state, allowing every device to derive the needed information to the routing support locally.Commonly, devices exchange summarized information (e.g., frequency of contacts, centrality, delivery predictability): an interesting approach for single routing, as it allows the exchange of the minimal amount of information; however, it is less attractive for a multi routing approach due to the high coupling between routing and property exchange. Creating an adaptative mechanism for a routing algorithm at runtime claims a careful choice considering multiple aspects of the development cycle: modeling, dynamic adaptation, and system extension. Runtime adaptability and extensibility support have been integrated into some programming languages. In some cases, it is also possible to provide those capabilities through development techniques and design patterns. However, at the modeling level, conceptual modeling languages, as the Entity-Relationship Model (ER) or the Unified Modeling Language (UML) cannot express the dynamics that arise from the context changes and behavioral interaction at runtime (e.g., the influence of congestion control techniques in the outcome of the routing algorithm according to a set of goals or intent of the network). Therefore, we used Role-based modeling languages to express the behavioral and relational nature of the proposed system. In a PTN, the router (vehicle or station) plays the role \textit{route} (executes an objective function) depending on the sensed context. The \textit{route} role can be further influenced by roles that encapsulate routing strategies, as congestion control (limiting the number of replication) or fairness. Routing algorithms are grouped in compartments and selected based on rules that determine what routing algorithm should be selected for a given context and how to tune the routing algorithm. A proof of concept was developed using SCROLL and integrated into the ONE simulator, allowing adaptive simulations. On the one hand, this solution is flexible, allowing algorithms to be designed independently. On the other hand, the integration between Java and SCALA reduced the system's flexibility due to the impossibility of using implicit types and the simulation time increased considerably. The potential performance improvement caused by routing adaptation depends on several variables, e.g., the scenario, the vehicular mobility, and the routing algorithms. Based on the evaluation of common routing algorithms proposed in DTN that can be reproduced by exchanging information about resources, we show that algorithms should be compared under average load. On the one hand, if the network load is low, all routing algorithms perform similarly, since all bundles are delivered; On the other hand, the network is congested regardless of the routing algorithm if the load is too high. Our experiments also indicate that routing algorithms able to explore the runtime behavior of the network are likely to achieve higher DP for an average load and highlighted the importance of proper tuning of each routing algorithm for the target scenario. The adaptive simulations showed that adapting the routing algorithm at runtime could increase the desired metric. Our simulations considered 24 hours of the tram PTN of Freiburg, in which we changed the mobility for a specific period of the day. In both experiments, we compare a historically based non-adaptive algorithm (PRoPHET) with an adaptive algorithm that modifies the behavior (PRoPHET and Epidemic) according to the context. In the first scenario, we simulate the effect of a disaster in which vehicular mobility is replaced by first aid vehicles. The adaptive variant resulted in a DP increase of up to 9.85\% at the end of the adaptation period. In the second scenario, we simulated mobility adaptation due to an accident that split two tramlines. Also, in this use case, the adaptation at runtime allowed the DP to increase up to 11.12\%. In both cases, the ability to perceive the context modification and adapt accordingly is essential. We evaluated the overhead of information exchange based on a concrete example for PTN and found that, for the chosen scenarios and multiple communication technologies, the network overhead caused by information exchange at runtime would be less than 1.2\%. The main contributions of this thesis are summarized as follows: we developed tools to support the creation and simulation of DTN in PTN scenarios; provided a classification of properties exchanged in the DTN literature to provide context awareness and support routing algorithms; pointed out a design decision in current frameworks (coupling between routing and property exchange) that precludes the adoption of current routing algorithms at runtime; reinforced, based on extensive simulations, the importance of tuning each routing algorithm to the target use-case; proposed a method to exchange and store properties that could enable nodes to collect historical data according to its resources (computing and storage space); demonstrated, for a specific property group how to break information into basic units and how to derive complex metrics for multiple purposes; last but not least, we demonstrated that, in scheduled networks, such as PTN, adaptive algorithms can increase the desired metric by adapting the routing algorithm at runtime. As future work remains the following question: how to effectively provide context awareness through the exchange of properties at runtime?

In a heterogeneous mobile ad hoc network (MANET), assorted devices with different computation and communication capabilities co-exist. In this thesis, we consider the case when the nodes of a MANET have various degrees of mobility and range, and the communication links are asymmetric. Many routing protocols for ad hoc networks routinely assume that all communication links are symmetric, if node A can hear node B and node B can also hear node A. Most current MAC layer protocols are unable to exploit the asymmetric links present in a network, thus leading to an inefficient overall bandwidth utilization, or, in the worst case, to lack of connectivity. To exploit the asymmetric links, the protocols must deal with the asymmetry of the path from a source node to a destination node which affects either the delivery of the original packets, or the paths taken by acknowledgments, or both. Furthermore, the problem of hidden nodes requires a more careful analysis in the case of asymmetric links. MAC layer and routing protocols for ad hoc networks with asymmetric links require a rigorous performance analysis. Analytical models are usually unable to provide even approximate solutions to questions such as end-to-end delay, packet loss ratio, throughput, etc. Traditional simulation techniques for large-scale wireless networks require vast amounts of storage and computing cycles rarely available on single computing systems. In our search for an effective solution to study the performance of wireless networks we investigate the time-parallel simulation. Time-parallel simulation has received significant attention in the past. The advantages, as well as, the theoretical and practical limitations of time-parallel simulation have been extensively researched for many applications when the complexity of the models involved severely limits the applicability of analytical studies and is unfeasible with traditional simulation techniques. Our goal is to study the behavior of large systems consisting of possibly thousands of nodes over extended periods of time and obtain results efficiently, and time-parallel simulation enables us to achieve this objective. We conclude that MAC layer and routing protocols capable of using asymmetric links are more complex than traditional ones, but can improve the connectivity, and provide better performance. We are confident that approximate results for various performance metrics of wireless networks obtained using time-parallel simulation are sufficiently accurate and able to provide the necessary insight into the inner workings of the protocols.

As the number of people using wireless networks is increasing, the need to reduce the vulnerability of wireless networks from node or link failures that cause loss of data is becoming a priority. Also the present techniques and topologies used for wireless networking are not sufficient to handle the traffic load even if we solve the issues of reliability and resilience. Packet loss or delay is increasingly likely due to the increase in the number of packets as technology is evolving and more video and voice packets along with the data packets are being transmitted. Only the efficient and intelligent use of the shared medium can solve the problem and help in avoiding the collision or delay among the packets using a newly proposed intelligent topology. Wireless technology offers the potential to replace wires from many applications, particularly for the rapid deployment of networks for permanent or temporary use. Fiber_ optic metropolitan area networks (WAN) provide security and resilience. A target of the research was to match this in the wireless environment. This research investigates the suitability if using wireless technology for the establishment of a MAN by adding features to enhance resilience. We proposed a mechanism that may be rapidly deployed and provide automatic configuration. Research work and simulation design has been used to develop a new wireless network topology for an efficient and intelligent packet transmission by identifying reliable routes. This novel idea will help give wireless as well as mobile technology a clear edge over wired technology, not only in the case of mobility but also in the case of security of data and other services. A decision based routing tree mechanism has been developed, that can establish routes in an ad-hoc network which may than be configured into a logical dual ring. At the same time the proposed system proposes to embed the quality of service mechanisms, resilience, and reliability features from RPR. The simulations were created using Microsoft Visual Studio.Net for the Decision based routing algorithm. The results were compared with an existing LAR algorithm. We have obtained 95% confidence intervals on all the performance analysis results to indicate accuracy.

The growing demand on the variety of internet applications requires management of large scale networks by efficient Quality of Service (QoS) routing, which considerably contributes to the QoS architecture. The biggest contemporary drawback in the maintenance and distribution of the global state is the increase in communication overheads. Unbalancing in the network, due to the frequent use of the links assigned to the shortest path retaining most of the network loads is regarded as a major problem for best effort service. Localised QoS routing, where the source nodes use statistics collected locally, is already described in contemporary sources as more advantageous. Scalability, however, is still one of the main concerns of existing localised QoS routing algorithms. The main aim of this thesis is to present and validate new localised algorithms in order to develop the scalability of QoS routing. Existing localised routing, Credit Based Routing (CBR) and Proportional Sticky Routing (PSR), use the blocking probability as a factor in selecting the routing paths and work with either credit or flow proportion respectively, which makes impossible having up-to-date information. Therefore our proposed Highest Minimum Bandwidth (HMB) and Highest Average Bottleneck Bandwidth History (HABBH) algorithms utilise bandwidth as the direct QoS criterion to select routing paths. We introduce an Integrated Delay Based Routing and Admission Control mechanism. Using this technique Minimum Total Delay (MTD), Low Fraction Failure (LFF) and Low Path Failure (LPF) were compared against the global QoS routing scheme, Dijkstra, and localised High Path Credit (HPC) scheme and showed superior performance. The simulation with the non-uniformly distributed traffic reduced blocking probability of the proposed algorithms. Therefore, we advocate the algorithms presented in the thesis, as a scalable approach to control large networks. We strongly suggest that bandwidth and mean delay are feasible QoS constraints to select optimal paths by locally collected information. We have demonstrated that a few good candidate paths can be selected to balance the load in the network and minimise communication overhead by applying the disjoint paths method, recalculation of candidate paths set and dynamic paths selection method. Thus, localised QoS routing can be used as a load balancing tool in order to improve the network resource utilization. A delay and bandwidth combination is one of the future prospects of our work, and the positive results presented in the thesis suggest that further development of a distributed approach in candidate paths selection may enhance the proposed localised algorithms. / Umm AlQura University in Mecca

Ensuring trustworthiness through mobile nodes is a serious issue. Indeed, securing the routing protocols in Mobile Ad Hoc Network (MANET) is of paramount importance. A key exchange cryptography technique is one such protocol. Trust relationship between mobile nodes is essential. Without it, security will be further threatened. The absence of infrastructure and a dynamic topology changing reduce the performance of security and trust in mobile networks. Current proposed security solutions cannot cope with eavesdroppers and misbehaving mobile nodes. Practically, designing a key exchange cryptography system is very challenging. Some key exchanges have been proposed which cause decrease in power, memory and bandwidth and increase in computational processing for each mobile node in the network consequently leading to a high overhead. Some of the trust models have been investigated to calculate the level of trust based on recommendations or reputations. These might be the cause of internal malicious attacks. Our contribution is to provide trustworthy communications among the mobile nodes in the network in order to discourage untrustworthy mobile nodes from participating in the network to gain services. As a result, we have presented an Elliptic Curve Diffie-Hellman key exchange and trust framework mechanism for securing the communication between mobile nodes. Since our proposed model uses a small key and less calculation, it leads to a reduction in memory and bandwidth without compromising on security level. Another advantage of the trust framework model is to detect and eliminate any kind of distrust route that contain any malicious node or suspects its behavior.

Environmental issues are a vital concern in today’s world. The Swedish government and local businesses are developing a sustainable business and eco-friendly environment for city inhabitants. Last-mile pickup and delivery services are a key concern, which significantly impacts the environment and society. The Norwegian/Swedish parcel delivery company Bring, the reusable waste management company Ragn-Sells, the city of Stockholm, the research institute Sustainable Innovation, and the KTH Royal Institute of Technology are jointly working together in the Intercitylog2 project with a vision to handle better last-mile pickups or deliveries that are jointly serviced by small electric vehicles from an urban micro terminal. This thesis addresses the optimizations of simultaneous pickup and delivery operations using homogeneous vehicles and considering vehicle capacity, time windows and environmental constraints. A mathematical model is developed to address the problem using an exact commercial solver. The quality of the solutions has been evaluated with real pickup and deliveries of the participating company. The primary objective function is formulated to minimize the travel cost by finding the shortest path, and the results are compared with current routing operation data. KPIs are developed and evaluated based on the facts and figures from the obtained results of the experiments. The two scenarios, big vehicles and small vehicles are also developed and evaluated to find the best route optimization opportunity for the companies. The results show that the optimized operation could decrease delivery distance by 36.72% and 37.13% and delivery time by 43.65% and 47.08% for big and small vehicles operations, respectively, compared to the current routing operations. A round trip can complete within a defined time frame to avoid the battery running out during a route. Energy constraints demonstrate that using electric vehicles considerably reduce significant amounts of CO2 emission from the environment. / Miljöfrågor är en viktig fråga i dagens värld. Den svenska regeringen och lokala företag arbetar tillsammans för att utveckla ett hållbart företagande och miljövänlig miljö för stadens invånare. Last-mile hämtning och leveranstjänster är en viktig fråga, som avsevärt påverkar miljön och samhället.Det norsk/svenska paketleveransföretaget Bring, återanvändbara avfallshanteringsföretaget Ragn- Sells, Stockholms stad, forskningsinstitutet Sustainable Innovation och Kungliga Tekniska Högskolan arbetar tillsammans i Intercitylog2-projektet för en vision för att bättre hantera last-mile pickuper eller leveranser som gemensamt betjänas av små elfordon från en urban mikroterminal. Detta examensarbete behandlar optimering av samtidiga hämtnings- och leveransoperationer med homogena fordon och med hänsyn till fordonskapacitet, tidsfönster och miljömässiga begränsningar. En matematisk modell utvecklas för att ta itu med problemet med en exakt kommersiell lösare och kvaliteten på lösningarna har utvärderats med verklig upphämtning och leveranser från det deltagande företaget. Den primära målfunktionen är formulerad för att minimera reskostnaden genom att hitta den kortaste vägen, och resultaten jämförs med aktuella ruttoperationsdata. KPI:er utvecklas och utvärderas utifrån fakta och siffror från de erhållna resultaten av experimenten. De två scenarierna, stora fordon och små fordon, är också utvecklade och utvärderade för att hitta den bästa ruttoptimeringsmöjligheten för företagen. Resultaten visar att den optimerade driften kan minska leveransavståndet med 36,72% och 37,13% och leveranstiden med 43,65% och 47,08% för stora och små fordonsoperationer, jämfört med nuvarande ruttoperationer. En tur och retur kan genomföras inom en definierad tidsram för att undvika att batteriet tar slut under en rutt. Energibegränsningar visar att användning av elfordon avsevärt minskar betydande mängder CO2-utsläpp från miljön.

One of the core principles of the SAP HANA database system is the comprehensive support of distributed query facility. Supporting scale-out scenarios was one of the major design principles of the system from the very beginning. Within this paper, we first give an overview of the overall functionality with respect to data allocation, metadata caching and query routing. We then dive into some level of detail for specific topics and explain features and methods not common in traditional disk-based database systems. In summary, the paper provides a comprehensive overview of distributed query processing in SAP HANA database to achieve scalability to handle large databases and heterogeneous types of workloads.

Cloud computing platforms allow users to deploy geographically distributed applications on servers around the world. Applications may be simple to deploy on these platforms, but it is up to the user and the application to decide which regions and servers to use for application placement. Furthermore, network conditions and routing between the geo-distributed servers change over time, which can lead to sub-optimal performance of applications deployed on such servers. A user could either employ a static deployment configuration of servers, or attempt to use a more dynamic configuration. However, both have inherent limitations. A static configuration will be sub-optimal, as it will be unable to adapt to changing network conditions. A more dynamic approach where an application could switch over or transition to a more suitable server could be beneficial, but this can be very complex in practice. Furthermore, such a solution is more about adapting to change as it happens, and not beforehand. This thesis will investigate the possibility of forecasting impending routing changes between servers, by leveraging messages generated by the Border Gateway Protocol (BGP) and past knowledge about routing changes. BGP routers can delay BGP updates due to factors such as the minimum route advertisement interval (MRAI). Thus, out proposed solution involves forwarding BGP updates downstream in the network, before BGP routers process them. As routing between servers changes, so does the latency, meaning that the latency then could be predicted to some degree. This observation could be applied to realize when the latency to a server increases or decreases past another server. This in turn facilitates the decision process of selecting the most optimal servers in terms of latency for application deployment. The solution presented in this thesis can successfully predict routing changes between end-points in an enclosed environment, and inform users ahead of time that the latency is about to change. The time gained by such predictions depend on factors such as the number of ASs between the end-points, the MRAI, and the update processing delay imposed on BGP routers. Time gains between tens of milliseconds to over 2 minutes has been observed.

In this dissertation, we propose service-oriented sensor-actuator networks (SOSANETs) as a new paradigm for building the next generation of customizable, open, interoperable sensor-actuator networks. In SOSANETs, nodes expose their capabilities to applications in the form of service profiles. A node's service profile consists of a set of services (i.e., sensing and actuation capabilities) that it provides and the quality of service (QoS) parameters associated with those services (delay, accuracy, freshness, etc.). SOSANETs provide the benefits of both application-specific SANETs and generic SANETs. We first define a query model and an architecture for SOSANETs. The proposed query model offers a simple, uniform query interface whereby applications specify sensing and actuation queries independently from any specific deployment of the underlying SOSANET. We then present μRACER (Reliable Adaptive serviCe-driven Efficient Routing), a routing protocol suite for SOSANETs. μRACER consists of three routing protocols, namely, SARP (Service-Aware Routing Protocol), CARP (Context-Aware Routing Protocol), and TARP (Trust-Aware Routing Protocol). SARP uses an efficient service-aware routing approach that aggressively reduces downstream traffic by translating service profiles into efficient paths. CARP supports QoS by dynamically adapting each node's routing behavior and service profile according to the current context of that node, i.e. number of pending queries and number and type of messages to be routed. Finally, TARP achieves high end-to-end reliability through a scalable reputation-based approach in which each node is able to locally estimate the next hop of the most reliable path to the sink. We also propose query optimization techniques that contribute to the efficient execution of queries in SOSANETs. To evaluate the proposed service-oriented architecture, we implemented TinySOA, a prototype SOSANET built on top of TinyOS with uRACER as its routing mechansim. TinySOA is designed as a set of layers with a loose interaction model that enables several cross-layer optimization options. We conducted an evaluation of TinySOA that included a comparison with TinyDB. The obtained empirical results show that TinySOA achieves significant improvements on many aspects including energy consumption, scalability, reliability and response time. / Ph. D.