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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Rozbor protokolů CISCO sítí / Protocols Analysis of CISCO Networks

Karlík, Martin January 2016 (has links)
ABSTRACT Bc.Karlík, Martin Department of Telecommunications, Faculty of Electrical Engineering and Communication, Brno University of Technology. Analysis of CISCO networking protocols This semestral thesis is focused on CISCO networks and protocols like MPLS, BGP, Ipv4, Ipv6, Multicast – sprase / dense mode. The task was study of those protocols and design and implement lab excercise with one of those protocols by using free network simulator GNS3. In this excercise is used CISCO router 3745.
42

SCALABLE HYBRID DATA DISSEMINATION FOR INTERNET HOT SPOTS

Zhang, Wenhui 17 January 2007 (has links)
No description available.
43

Minimizing Overlap in Tree-Based Multipoint Communication

Wang, Yanhua 31 May 2005 (has links)
No description available.
44

Application Layer Multipoint Extension for the Session Initiation Protocol

Thorp, Brian J. 04 May 2005 (has links)
The Session Initiation Protocol (SIP) was first published in 1999, by the Internet Engineering Task Force (IETF), to be the standard for multimedia transfers. SIP is a peer-to-peer signaling protocol that is capable of initiating, modifying, and terminating media sessions. SIP utilizes existing Internet Protocols (IP) such as Domain Name Service (DNS) and the Session Description Protocol (SDP), allowing it to seamlessly integrate into existing IP networks. As SIP has matured and gained acceptance, its deficiencies when functioning as a multipoint communications protocol have become apparent. SIP currently supports two modes of operation referred to as conferencing and multicasting. Conferencing is the unicast transmission of session information between conference members. Multicasting uses IP multicast to distribute session information. This thesis proposes an extension for the Session Initiation Protocol that improves functionality for multipoint communications. When using conferencing, a SIP user-agent has limited information about the conference it is taking part in. This extension increases the awareness of a SIP node by providing it with complete conference membership information, the ability to detect neighboring node failures, and the ability to automatically repair conference partitions. Signaling for conferencing was defined and integrated into a standard SIP implementation where it was used to demonstrate the above capabilities. Using a prototype implementation, the additional functionality was shown to come at the cost of a modest increase in transaction message size and processing complexity. IP multicast has limited deployment in today's networks reducing the usability of this useful feature. Since IP multicast support is not guaranteed, the use of application layer multicast protocols is proposed to replace the use of IP multicast. An efficient means of negotiating an application layer protocol is proposed as well as the ability to provide the protocol with session information to begin operation. A ring protocol was defined and implemented using the proposed extension. Performance testing revealed that the application layer protocol had slightly higher processing complexity than conferencing, but on average had a smaller transaction message size. / Master of Science
45

Τεχνικές μείωσης της εκπεμπόμενης ισχύος κατά τη multicast μετάδοση δεδομένων σε δίκτυα κινητών επικοινωνιών τρίτης γενιάς

Λάμπου, Άννα 10 March 2014 (has links)
Η αυξημένη ζήτηση για λήψη δεδομένων της πολυμεσικής Broadcast/Multicast υπηρεσίας από τους χρήστες των δικτύων κινητών επικοινωνιών τρίτης γενιάς, απαιτεί την κατανάλωση μεγάλων ποσών ισχύος για την εξυπηρέτησή τους, ενώ η διαθέσιμη ισχύς των δικτύων είναι περιορισμένη. Με στόχο, την αποδοτικότερη χρήση των ποσών ισχύος του συστήματος, και την εξυπηρέτηση με τον τρόπο αυτό περισσότερων χρηστών, αλλά με ταυτόχρονη διατήρηση της ποιότητας της υπηρεσίας, έχουν προταθεί κάποιες τεχνικές οι οποίες οδηγούν σε μείωση της εκπεμπόμενης ισχύος. Στην διπλωματική αυτή εργασία, αναλύονται αρχικά τα δίκτυα τρίτης γενιάς καθώς και η πολυμεσική Broadcast/Multicast υπηρεσία. Στη συνέχεια, περιγράφονται όλες οι τεχνικές που έχουν προταθεί, και με την χρήση κατάλληλου λογισμικού προσομοιώνεται μία από τις τεχνικές αυτές. Τα ποσοστά μείωσης ισχύος, που προκύπτουν ως αποτελέσματα της προσομοίωσης αυτής, αποδεικνύουν την σημαντική μείωση της εκπεμπόμενης ισχύος που μπορεί να επιτευχθεί με την χρήση της τεχνικής αυτής. / The increased demand for data download of the Multimedia Broadcast/Multicast service by the users of the mobile third generation networks, requires the consumption of large power amounts for their service, while the available power of the networks is limited. With the view of more efficient usage of the system power resources, and the service in this way of more users, but with the simultaneous maintenance of the quality of service, they have been proposed some techniques which lead to the reduction of the transmitted power. In this work, initially, the third generation networks and the Multimedia Broadcast/Multicast service are being analyzed. Afterwards, all the techniques that they have been proposed are being described, and with the usage of the appropriate software, one of these techniques is being simulated. The power reduction percentages, that they come of as a result of this simulation, prove the significant transmitted power reduction, which can be achieved with the usage of this technique.
46

Simmcast como ferramenta de simulação para avaliação de protocolos de roteamento multicast

Casais, Rosana 10 December 2002 (has links)
Made available in DSpace on 2015-03-05T13:53:43Z (GMT). No. of bitstreams: 0 Previous issue date: 10 / Nenhuma / Com o desenvolvimento das redes de computadores e o surgimento de sistemas com padrões mais complexos de comunicação, os simuladores tornaram-se ferramentas importantes e amplamente utilizadas para desenvolvimento, teste e avaliação de protocolos de comunicação em rede. As vantagens do uso de simuladores incluem a rapidez na geração de protótipos de protocolos e a possibilidade de criar cenários de simulação sem que seja necessário o uso de uma infra-estrutura física de rede. Este trabalho oferece o suporte necessário para simular protocolos de roteamento no ambiente de simulação de protocolos Simmcast. Inicialmente apresenta um estudo dos principais protocolos de roteamento intra e inter-domínios existentes na Internet, responsáveis pelo encaminhamento de pacotes em uma transmissão multicast, buscando apresentar uma abordagem comparativa entre as características necessárias para a realização de roteamentos eficientes. Em um segundo momento são exploradas as versões original da implementação do simulador de p
47

Avaliação do protocolo multicast e PePcc para transmissões confiáveis na Internet / Evaluation of the Pepcc protocol for reliable multicast transmission in the Internet

Peradotto, Roberto 03 April 2003 (has links)
Made available in DSpace on 2015-03-05T13:53:45Z (GMT). No. of bitstreams: 0 Previous issue date: 3 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Aplicações como a World-Wide Web, correio eletrônico e transferência de arquivos são a principal fonte de tráfego em redes de comunicação entre computadores hoje em dia. A tecnologia IP, base da Internet, não dispõe de reservas de recursos, e a divisão justa da capacidade da rede entre os fluxos que competem se dá através de mecanismos que devem estar presentes nos protocolos executados nas estações fim (hosts). Tal é denominado controle de congestionamento fim a fim. O tráfego na Internet é predominantemente composto por fluxos TCP, que é dotado de controle de congestionamento. Para o bom funcionamento da Internet, novos protocolos de transporte ou de aplicação devem incluir mecanismos de controle de congestionamento que sejam "amigáveis" ao TCP, ou seja, que não ocupem mais recursos do que deveriam. O surgimento de IP multicast viabilizou, no final nos anos 90, novas aplicações na Internet, como aplicações de trabalho em grupo, bancos de dados distribuídos, vídeo-conferência, etc. Muitas dessas aplicações
48

Layered Video Multicast Using Fractional Frequency Reuse over Wireless Relay Networks

Chen, Ying-Tsuen 27 September 2011 (has links)
Multimedia services over wireless networks are getting popular. With multicast many mobile stations can join the same video multicast group and share the same radio resource to increase frequency utilization efficiently. However users may locate at different positions so as to suffer different path loss, interference and receive different signal to interference and noise ratio (SINR). Users at the cell-edge receiving lower SINR may degrade the multicast efficiency. In this thesis we propose four schemes considering fractional frequency reuse (FFR) over relay networks to reuse frequency in multi-cells. With fractional frequency reuse, users close to the base station (BS) have more resources to improve the total frequency utilization. A resource allocation scheme is also proposed to efficiently allocate wireless resources. Compared to the conventional relay scheme, the proposed schemes can provide more than 10% video layers for all users and give better video quality for users near BS.
49

Multi-Constrained Quality of Service Routing in Networks / Routage avec contraintes de Qualité de Service multiple dans les réseaux

Khallef, Walid 24 November 2017 (has links)
Au cours des dernières années, le trafic réseau nécessitant une qualité de service (QoS) a augmenté de façon exponentielle. Dans cette thèse, notre objectif est de trouver des routages dans les réseaux câblés et sans fil en prenant en compte les contraintes liées à la QoS et en minimisant le coût de la communication. Nous nous intéressons tout d’abord à la résolution du problème du chemin multi-contraint (MCP) pour lequel un algorithme exact efficace est proposé. Cet algorithme permet d'améliorer le temps d'exécution tout en maintenant la qualité de la solution. En ce qui concerne le problème de la diffusion multipoint (multicast) multi-contraint de coût minimal (MCMCM), une nouvelle formulation utilisant la Programmation Linéaire en Nombres Entiers est proposée. Elle permet de calculer les hiérarchies optimales, structures les plus pertinentes pour résoudre de manière exacte le problème MCMCM. Un algorithme de prétraitement efficace est également conçu pour accélérer le temps de résolution dans les réseaux de grande taille. En ce qui concerne le problème du routage avec QoS dans les « Low Power et Lossy Networks » (LLN), une solution basée sur une nouvelle fonction objective est présentée. Cette solution minimisant une longueur non linéaire est la première à prendre en compte un nombre quelconque de contraintes pour le routage avec QoS. Nous avons conçu un algorithme exact et deux algorithmes de routage heuristique pour résoudre ce problème dans les réseaux LLN avec QoS. / In recent years, the network traffic requiring Quality of Service (QoS) has been growing explosively. In this thesis, we study the multi-constrained QoS routing in networks. The objective is to find routes in wired and wireless networks taking into account constraints related to the QoS and minimizing the cost of the communication. We present several propositions. To solve the Multi-Constrained Path problem (MCP), an efficient exact algorithm is proposed. This algorithm is shown to be able to improve the execution time while maintaining the quality of the solution. Concerning the Multi-Constrained Multicast Minimum Cost problem (MCMCM), a new Integer Linear Programming (ILP) formulation is proposed to compute hierarchies, which are the exact solutions for MCMCM. An efficient preprocessing-based algorithm is also designed to accelerate the resolution time in large size networks. Regarding the problem of QoS routing in Low Power and Lossy Networks (LLNs), a new Objective Function (OF)-based solution is presented. This solution uses a non-linear length function. It is the first that takes into account any number of metrics and constraints for QoS routing. We designed an exact and two heuristic routing algorithms with QoS constraints for LLNs.
50

Communication multicast pour les systèmes véhiculaires coopératifs / Multicast communications for cooperative vehicular systems

Ben Jemaa, Inès 17 December 2014 (has links)
La communication véhiculaire permet le développement de nouvelles applications multicast émergentes telles que la gestion de la flotte et la distribution des Points d'Intérêt (POI). Ces deux catégories d'applications nécessitent une communication multicast de l'Internet vers les réseaux véhiculaires (VANET). Afin de mettre en place une communication multicast adaptée au contexte de la communication Internet-vers-réseaux véhiculaires, notre travail traite de deux aspects différents. Tout d'abord, l'accessibilité des véhicules en mouvement au service Internet et en deuxième lieu, la dissémination du message dans les VANET. Nous introduisons un schéma d'adressage multicast basé sur les coordonnées géographiques des véhicules qui leur permet de s'auto-configurer d'une façon dynamique sans aucun besoin d'échanger des messages de signalisation avec Internet. Nous proposons aussi une approche simplifiée de gestion de la mobilité des véhicules dans le cadre des architectures Mobile IP et Proxy Mobile IP. Le but de cette approche est d'optimiser l'échange des messages avec les entités responsables de la gestion de la mobilité dans Internet. Afin d'étudier les mécanismes de dissémination appropriés aux applications de gestion de flottes, nous nous proposons de revisiter les techniques de routage multicast traditionnelles basées sur une structure de diffusion en arbre. Pour cela, nous étudions leur application aux réseaux véhiculaires. Nous présentons une étude théorique portant sur la durée de vie des liens entre les véhicules en milieux urbains. Ensuite, en utilisant la simulation, nous étudions l'application de Multicast Adhoc On Demand Vector, MAODV et proposons Motion-MAODV, une version adaptée de MAODV qui a pour objectif d'établir des routes plus robustes Enfin, concernat la dissémination multicast géolocalisée dans les applications POI, nous proposons le protocole de routage Melody qui permet une diffusion geocast en milieu urbain. A partir de simulations, nous constatons que, comparé aux protocoles de géo-brodcasting dans les milieux urbain très denses, Melody assure plus de fiabilité et d'efficacité lors de l'acheminement des données vers les zones géographiques de destination. / Vehicular communications allow emerging new multicast applications such as fleet management and point of interest (POI). Both applications require Internet-to-vehicle multicasting. These approaches could not be applied to vehicular networks (VANET) due to their dynamic and distributed nature. In order to enable such multicasting, our work deals with two aspects. First, reachability of the moving vehicles to the multicast service and second, multicast message dissemination in VANET. We introduce first a self-configuring multicast addressing scheme that allows the vehicles to auto-configure a dynamic multicast address without a need to exchange signalling messages with the Internet. Second, we propose a simplified approach that extends Mobile IP and Proxy Mobile IP. This approach aims at optimizing message exchange between vehicles and entities responsible for managing their mobility in Internet. To study the dissemination mechanisms that are suitable for fleet management applications, we propose to revisit traditional multicast routing techniques that rely on a tree structure. For this purpose, we study their application to vehicular networks. In particular, as vehicular networks are known to have changing topology, we present a theoretical study of the link lifetime between vehicles in urban environments. Then, using simulations, we study the application of Multicast Adhoc On Demand Vector, MAODV. We propose then Motion-MAODV, an improved version of MAODV that aims at enhancing routes built by MAODV in vehicular networks and guarantee longer route lifetime. Finally, to enable geographic dissemination as required by POI applications, we propose a routing protocol Melody that provides a geocast dissemination in urban environments. Through simulations, Melody ensures more reliable and efficient packet delivery to a given geographic area compared to traditional geo-brodcasting schemes in highly dense scenarios.

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