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La conception d'un réseau de capteurs sans fil peut présenter de nombreux défis, tels que le passage à l'echèlle, la fiabilité, la longévité et la communication en temps réel. L'existence de plusieurs points de collecte peut augmenter la fiabilité du réseau et facilite le passage à l'echèlle. Toutefois, cette amélioration dépend de l’approche de routage, qui doit être adaptée pour atteindre les objectifs de performance souhaités.Dans cette optique, l’objectif de ce travail est de trouver des moyens pour optimiser la communication dans les réseaux de capteurs sans fil à multiples points de collecte en tenant compte des problèmes liés au passage à l'echèlle, à la durée de vie du réseau, à la fiabilité (livraison des paquets) et à la minimization de la latence. Nous étudions les point d'équilibre entre le délai et la consommation d'énergie en tant que paramètres clés pour la qualité et l'efficacité de la communication. Pour ce faire, nous proposons différents algorithmes de routage, couvrant les trois principaux schémas de communication (unicast, anycast et multicast).Les simulations effectuées montrent que nos approches sont capables d’optimiser la communication, notamment en termes de latence et de durée de vie du réseau. Des expériences sur la plateforme FIT IoT-Lab fournissent également des indications significatives sur les performances de notre solution multicast dans des conditions réelles. / The conception of a wireless sensor network may present numerous challenges, such as scalability, reliability, longevity and timeliness. The existence of multiple sinks may increase the network reliability and facilitates the scalability. However, this improvement is dependent on the routing approach, that must be tailored to help achieving the desired performance goals.From this perspective, the objective of this work is to find ways of optimizing the communication in multi-sink wireless sensor networks considering the problems related to the scalability, longevity (network lifetime), reliability (packet delivery) and timeliness (latency). We investigate the trades among data delivery time and energy consumption as key metrics for communication quality and efficiency. For that matter, we propose different routing algorithms, covering all three main communciations schemes (unicast, anycast and multicast).The executed simulations show that our approaches are capable of optimizing the communication, especially in terms of latency and network lifetime. Experiments on the FIT IoT-Lab platform also provide meaningful insights of the performance of our multicast solution in real environment condition.

La technologie des réseaux de capteurs sans fil (RCSF) est l’un des éléments constitutifs de l’Internet des objets (IoT). En raison de leurs caractéristiques de déploiement facile et de leur flexibilité, ils sont utilisés dans de nombreux domaines d’application. Les réseaux à faible consommation et à perte (LLN) sont un type spécial de WSN dans lequel les noeuds sont largement limités en ressources. Convergecast est l’un des modes de communication de base, dans lequel tout le trafic du réseau est destiné à une destination prédéfinie appelée collecteur. Tout en prenant en compte les domaines d’applications IoT, convergecast n’est pas le seul mode de communication sur le réseau. Le récepteur doit envoyer des commandes à certains capteurs pour effectuer des actions. Dans cette application, anycast est un autre mode de communication de base. Dans anycast, le trafic provenant du récepteur est destiné à tout membre d’un groupe de récepteurs potentiels du réseau.Les LLN sont formés de noeuds de capteurs statiques et changent rarement de position. En raison des contraintes de ressources strictes imposées au calcul, à l’énergie et à la mémoire des LLN, la plupart des protocoles de routage ne prennent en charge que les réseaux statiques. Cependant, la mobilité est devenue une exigence importante pour de nombreuses applications émergentes. Dans ces applications, certains noeuds sont libres de se déplacer et de s’organiser dans un réseau connecté. La topologie changerait continuellement en raison du mouvement des noeuds et de l’instabilité des liaisons radio. Il s’agit d’une tâche difficile pour la plupart des protocoles de routage des réseaux LLN afin de s’adapter rapidement au mouvement et de reconstruire la topologie en temps voulu. Le but de cette thèse est de proposer un support de mobilité efficace pour les protocoles de routage dans les réseaux LLN. Nous nous concentrons sur convergecast et anycast, qui sont les modes de communication les plus utilisés dans les réseaux LLN, dans les scénarios de réseau mobile. Nous proposons un mécanisme d’amélioration, nommé RL (RSSI and Level),pour prendre en charge les protocoles de routage dans les réseaux LLN convergecast en mobilité. Ce mécanisme aide le protocole de routage à prendre des décisions plus rapides pour la détection de la mobilité et la mise à jour des voisins du saut suivant,mais souffre d’une surcharge importante. Nous proposons une gestion dynamique des messages de contrôle pour améliorer les performances de RL et l’implémentons en plus du protocole de routage pour réseau à faible consommation (RPL) et nous l’avons nommé RRD (RSSI, Rank and Dynamic). Après une prise en compte de l’hystérésis de la zone de couverture de la plage de transmission des noeuds, nousavons optimisé RRD. Cette version améliorée s’appelle RRD +. Sur la base de RRD+, nous avons proposé MRRD + (Multiple, RSSI, Rank et Dynamic) pour prendre en charge plusieurs puits dans les réseaux LLN convergecast en mobilité. ADUP (Adaptive Downward / Upward Protocol) est une solution de routage prenant en charge simultanément convergecast et anycast dans les réseaux LLN. Nous avons évalué les performances de nos contributions à la fois en simulation avec le simulateur Cooja et en expérience (uniquement pour ADUP) sur des motosTelosB. Les résultats obtenus en simulation et en expérience confirment l’efficacité de nos protocoles de routage. / Wireless Sensor Networks (WSNs) technology is one of the building blocks ofthe Internet of Things (IoT). Due to their features of easy deployment and flexibility,they are used in many application domains. Low-Power and Lossy Networks(LLNs) are a special type of WSNs in which nodes are largely resources constrained.For LLNs, convergecast is one of the basic traffic modes, where all traffic in the networkis destined to a predefined destination called the sink. While considering theIoT application domains, convergecast is not the only traffic mode in the network.The sink needs to send commands to certain sensors to perform actions. In this application,anycast is another basic traffic mode. In anycast, the traffic from the sinkis destined to any member of a group of potential receivers in the network.Traditionally LLNs are formed by static sensor nodes and rarely change positions.Due to the strict resource constraints in computation, energy and memory ofLLNs, most routing protocols only support static network. However, mobility hasbecome an important requirement for many emerging applications. In these applications,certain nodes are free to move and organize themselves into a connectednetwork. The topology would continuously change due to the movement of nodesand radio links instability. This is a hard task for most routing protocols of LLNs toadapt rapidly to the movement and to reconstruct topology in a timely manner.The goal of this thesis is to propose an efficient mobility support for routingprotocols in LLNs. We focus on convergecast and anycast, which are the most usedtraffic modes in LLNs, in mobile network scenarios.We propose an enhancement mechanism, named RL (RSSI and Level), to supportrouting protocols in convergecast LLNs in mobility. This mechanism helps routingprotocol make faster decisions for detecting mobility and updating next-hop neighborsbut suffers from high overhead. We propose a dynamic control message managementto enhance the overhead performance of RL and implement it on top ofRouting Protocol for Low-power and Lossy network (RPL) and we named it RRD(RSSI, Rank and Dynamic). After taking into account hysteresis of the coveragezone of the transmission range of nodes, we optimized RRD. This enhanced versionis called RRD+. Based on RRD+, we proposed MRRD+ (Multiple, RSSI, Rankand Dynamic) to support multiple sinks in convergecast LLNs in mobility. ADUP(Adaptive Downward/Upward Protocol) is a routing solution that supports bothconvergecast and anycast in LLNs concurrently.We evaluated the performance of our contributions in both simulation usingCooja simulator and experiment (only for ADUP) on TelosB motes. The resultsobtained in both simulation and experiment confirm the efficiency of our routingprotocols.

One of the main challenges in the Multi-access Edge Computing (MEC) issteering traffic from clients to the nearest MEC instances. If the nearest MECfails, a failover mechanism should provide mitigation by steering the trafficto the next nearest MEC. There are two conventional approaches to solve thisproblem, i.e., GeoDNS and Internet Protocol (IP) anycast. GeoDNS is notfailover friendly because of the Domain Name System (DNS) cache lifetime.Moreover, the use of a recursive resolver may inaccurately translate the IPaddress to its geolocation. Thus, this thesis studies and proposes a highlyavailable MEC platform leveraging IP anycast. We built a proof-of-conceptusing Kubernetes, MetalLB, and a custom health-checker running on theGNS3 network emulator. We measured latency, failure percentage, and MeanTime To Repair (MTTR) to observe the system’s behavior. The performanceevaluation of the proposed solution shows an average recovery time betterthan one second. The number of failed requests and latency overhead growslinearly as the failover time and latency between two MECs increases. Thisthesis demonstrates the effectiveness of IP anycast for MEC applications tosteer the traffic to the nearest MEC instance and to enhance resiliency withminor overhead. / n av de största utmaningarna i Multi-access Edge Computing (MEC) är attstyra trafiken från klienter till närmaste MEC instanser. Om den närmasteMEC misslyckas, bör en failover-mekanism ge begränsning genom att styratrafiken till nästa närmaste MEC. Det finns två konventionella metoder för attlösa detta problem, dvs GeoDNS och IP anycast. GeoDNS är inte failovervänligtpå grund av DNS-cache-livslängd. Dessutom kan användningen aven rekursiv upplösare felaktigt översätta IP-adressen till dess geolokalisering.Således studerar och föreslår denna avhandling en mycket tillgänglig MEC-plattform som utnyttjar IP anycast. Vi byggde ett proof-of-concept medKubernetes, MetalLB och en anpassad hälsokontroll som körs på GNS3-nätverksemulatorn. Vi mätte latens, felprocent och Mean Time To Repair(MTTR) för att observera systemets beteende. Prestationsutvärderingen avden föreslagna lösningen visar en genomsnittlig återhämtningstid som ärbättre än en sekund. Antalet misslyckade förfrågningar och latensomkostnaderväxer linjärt när failover-tiden och latensen mellan två MEC ökar. Den häravhandlingen visar effektiviteten hos IP anycast för MEC-applikationer för attstyra trafiken till närmaste MEC instans och för att förbättra elasticiteten medmindre overhead.

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In these few years, gradually Internet develops to wideband, multimedia is being used on video or music. In addition, the use of IP Multicast must be based on the deployment of routers, which is too difficult to arrange. Utilities of Application Layer Multicast is in the middle and just between IP Multicast and Unicast.Therefore, in this paper, Application Layer Multicast is still worth to study it. In this paper, is applied effectively build the Application Layer Multicast. Control through the IP Anycast Technique, we can lower the time for host join the Multicast Tree. Every host can join the nearest cluster. We use the hierarchical cluster-based Method in order to serve more hosts. This concept about cluster can substantially decrease control overhead. The Complete Binary Trees lower the cluster leader¡¦s burden, also phased RTT decided effectively the transit sequence. In Summary, associate techniques with methods, to make up the defects from NICE and I-Zigzag.

No description available.

The Domain Name System (DNS) provides a mapping between host names and Internet Protocol (IP) addresses. Hosts that are configured using the Dynamic Host Configuration Protocol (DHCP) can have their assigned IP addresses updated in a Dynamic DNS (DDNS). DNS and DDNS are critical components of the Internet. Most applications use host names rather than IP addresses, allowing the underlying operating system (OS) to translate these host names to IP addresses on behalf of the application. When the DDNS service is unavailable, applications that use DNS cannot contact the hosts served by that DDNS server. Unfortunately, the current DDNS implementation cannot continue to operate under failure of a master DNS server. Although a slave DNS server can continue to translate names to addresses, new IP addresses or changes to existing IP addresses cannot be added. Therefore, those new hosts cannot be reached by the DDNS. A new architecture is presented that eliminates this single point of failure. In this design, instead of storing resource records in a flat text file, all name servers connect to a Lightweight Directory Access Protocol (LDAP) directory to store and retrieve resource records. These directory servers replicate all resource records across each other using a multi-master replication mechanism. The DHCP servers can add records to any of the functioning DNS servers in event of an outage. In this scheme, all DNS servers use the anycast Border Gateway Protocol (BGP). This allows any of the DNS servers to answer queries sent to a single IP address. The DNS clients always use the same IP address to send queries. The routing system removes routes to non-functional name servers and delivers the request to the closest (according to network metrics) available DNS server. This thesis also describes a concrete implementation of this system that was created to demonstrate the viability of this solution. A reference implementation was built in a laboratory to represent an Internet Service Provider (ISP) with three identical regions. This implementation was built using Quagga as the BGP routing software running on a set of core routers and on each of the DNS servers. The Berkeley Internet Name Daemon (BIND) was used as an implementation of the DNS. The BIND Simplified Database Backend (SDB) interface was used to allow the DNS server to store and retrieve resource records in an LDAP directory. The Fedora Directory Server was used as a multi-master LDAP directory. DHCP service was provided by the Internet Systems Consortium's (ISC) DHCP server. The objectives for the design were high-availability, scalability and consistency. These properties were analyzed using the metrics of downtime during failover, replication overhead, and latency of replication. The downtime during failover was less than one second. The precision of this metric was limited by the synchronization provided by the Network Time Protocol (NTP) implementation used in the laboratory. The network traffic overhead for a three-way replication was shown to be only 3.5 times non-replicated network traffic. The latency of replication was also shown to be less than one second. The results show the viability of this approach and indicate that this solution should be usable over a wide area network, serving a large number of clients. / Master of Science

Att en hemsida tar extra lång tid att ladda är inte ovanligt och kan bero på att trafiken från en klient tar en helt annan väg till hemsidans server än den som är geografiskt närmast. Orsaken bakom problemet är att DNS-förfrågningarna färdas onödigt långa sträckor. NetNod är ett företag som tillhandahåller dessa internettjänster, bland annat rotservrar runt om i världen. De vill ta reda på varför trafik från olika klienter inte alltid går den geografiskt närmaste vägen till deras anycastnoder Problemställningen för examensarbetet är att analysera varifrån trafik till företagets anycastnod i Miami kommer. Realiseringen av detta gjordes genom att utveckla en programkod som markerade geografisk placering av olika klienter utifrån deras IP-adress. Förinspelade trafikdata från NetNod analyserades. Detta gjordes för att visa på vilka problem som observeras i peering och anycastrouting mellan internetprotokoll. Resultatet redovisades med en karta med markeringar av de IP-adresser där deras trafik analyserades för att se hur det transporterades till anycastnoden. Utifrån detta har resultatet visat på vilka avvikelser och mönster som uppstått inom BGP-routing när trafiken färdas till anycastnoden. De avvikelser som hittats är hur olika routingregler manipulerat trafikens transport till anycastnoden och gör att trafiken från klienterna inte tar den geografiskt närmaste vägen till anycastnoden. / The fact that a website takes an unusually long time to load is not uncommon. This can be due to a client taking a different path to the websites server than one that is geographically closer. One reason behind this problem is that DNS-queries travel unnecessarily long distances. NetNod is a company that provides internet services and maintains one of the few root-servers around the world. The company wants to know why traffic from different clients do not always go via the geographically closest route to anycast nodes. The objective of the thesis is to analyze where traffic to NetNods anycast node in Miami geographically originates from. In order to do this, a computer program was developed in which plots the geographical location of different clients from their IP-address. Pre-recorded data from the company was used as a data source for the program. This was done to show different challenges in peering and anycast routing between internet protocols. The result is presented via a map with plots of where the IP-addresses are geographically coming from to the anycast node in Miami, it was generated by the developed program. The generated map showed anomalies and patterns of how the traffic is transported in large junctions as well as how routing rules are applied, this is one reason to why the traffic does not always go the geographically closest route.

The goal of this thesis was to design two complex scenarios with focus on different kinds of transmission in packet-switched networks. First scenario is about ARQ (Automatic Repeat Request) protocols. It consists of introduction to Stop-and-Wait, Go Back N and Selective Repeat protocols and their comparison. Second scenario compares unicast, multicast, broadcast and anycast transmission methods. Both scenarios use applications which can simulate particular methods or protocols. These applications along with virtual environments are used for demonstration of characteristics of these methods/protocols.