Overlay Network

Traditional software and security patch update delivery mechanisms rely on a client/server approach where clients pull updates from servers regularly. This approach, however, suffers a high window of vulnerability (WOV) for clients and the risk of a single point of failure. Overlay-based information dissemination schemes overcome these problems, but often incur high infrastructure cost to set up and maintain individual information dissemination networks. Against

Both Mobile Ad Hoc Networks (MANETs) and Peer-to-Peer (P2P) Overlay Networks are decentralized and self-organizing networks with dynamic topology and responsible for routing queries in a distributed environment. Nevertheless, MANETs are composed of resource-constrained devices susceptible to faults, whereas P2P networks are fault-tolerant. Thus, we argue that these systems are not only similar, but also complementary, and that P2P networks are the ideal data sharing system for MANETs. This paper tackles the problem of integrating both networks from the point of view of content discovery. For that, we confront two classes of strategies: the structured strategy -based on distributed indexing -with the unstructured -based on flooding searches. More specifically, we study the performance of two P2P content discovery protocols over a MANET: Chord (structured) and Gnutella (unstructured). We use simulation to evaluate both protocols under many aspects and conclude that the choice of the strategy to be used depends on the application characteristics and the environment where it would be employed. Resumo. Ambas as Redes Móveis Ad hoc (MANETs) e as Redes Par-a-Par (P2P) são auto-organizáveis, de natureza descentralizada e responsáveis por rotear requisic ¸ões em ambientes distribuídos de topologia dinâmica. Entretanto, enquanto as MANETs são compostas de dispositivos com poucos recursos e, portanto, suscetíveis a falhas, as redes P2P são conhecidas pela sua tolerância a falhas. Por esta razão, sustentamos que MANETs e redes P2P não são apenas similares, mas também complementares e que sistemas P2P são ideais para se compartilhar arquivos em MANETs. Este trabalho aborda a integrac ¸ão dessas duas redes do ponto de vista de localizac ¸ão de conteúdo. Para tal, confrontamos a estratégia estruturada -que utiliza índexac ¸ão distribuídacom a não estruturada -que emprega flooding nas buscas. Mais especificamente, estudamos o desempenho sobre uma MANET de dois protocolos P2P de localizac ¸ão de conteúdo: Chord (estruturado) e Gnutella (não-estruturado). Utilizamos simulac ¸ão para efetuar os estudos sob diversos cenários e os resultados indicam que a escolha da estratégia a empregar dependerá da aplicac ¸ão e do ambiente em que será utilizada. O advento da computac ¸ão móvel e o avanc ¸o da Internet nos últimos anos possibilitou o aparecimento de novas tecnologias e a quebra de paradigmas. Dentre tais tecnologias duas têm obtido especial atenc ¸ão devido à vasta gama de aplicac ¸ões que oferecem e à facilidade de * Trabalho desenvolvido com apoio do CNPq/MCT e da CAPES/MEC.

We describe a new scalable application-layer multicast protocol, specifically designed for low-bandwidth, data streaming applications with large receiver sets. Our scheme is based upon a hierarchical clustering of the application-layer multicast peers and can support a number of different data delivery trees with desirable properties.We present extensive simulations of both our protocol and the Narada application-layer multicast protocol over Internet-like topologies. Our results show that for groups of size 32 or more, our protocol has lower link stress (by about 25%), improved or similar end-to-end latencies and similar failure recovery properties. More importantly, it is able to achieve these results by using orders of magnitude lower control traffic.Finally, we present results from our wide-area testbed in which we experimented with 32-100 member groups distributed over 8 different sites. In our experiments, average group members established and maintained low-latency paths and ...

Researchers are directing enormous efforts to achieve the aim of global mobility by enhancing the standard mobile IP with various routing schemes focusing on best routes and least cost while ignoring the facts of the organizations usual use of private IP’s and the presence of firewalls. Nevertheless, existing Mobile IP models are still missing three basic concepts that hinder their applicability in real environment. First, global mobility must be independent of the different infrastructure technologies (e.g., Wi-Fi, WiMAX, UMTS, etc.). Second, a secure authentication mechanism for guiding the access of mobile nodes to the corporate network’s resources is certainly needed. Third, the capability of correlating the mobile node’s activities to a real world identity is a requirement of security in a wider since i.e., network, web, and national security. This paper defines the role of global mobility in facilitating and improving mobile business performance. It, also, presents a review of...

Despite its popularity, relatively little is known about the traffic characteristics of the Skype VoIP system and how they differ from other P2P systems. We describe an experimental study of Skype VoIP traffic conducted over a five month period, where over 82 mil-lion datapoints were ...

They appeared in our life some years ago with the awakening of the PC and now the are everywhere : computers have become ubiquitous and, almost, irreplaceable. Classical ways of creating, managing and exchanging information have been progressively replaced by electronic means. In spite of this plebiscite, computer supported collaborative work (CSCW) softwares can be blamed for requiring the user to do an effort to use them. This paper describes an artificial ant based autonomous information dissemination algorithm. It constitutes the communication layer of our framework PIAF ("Personal Intelligent Agent Framework") intended to help users transparently sharing information. The algorithm uses message gossiping strategy to transfer information items between users.

Adequately supporting applications with Quality-of-service (QoS) requirements is a challenging task, particularly in the Internet. In great part, this is due to the fact that the provisioning of end-toend QoS to traffic that traverses multiple autonomous systems (ASes) requires a level of cooperation between ASes that is difficult to achieve in the current architecture. Recently, service overlay networks have been considered as an approach to QoS deployment that avoids these difficulties. In this study, the problem of the topological synthesis of a service overlay network is addressed. Endsystems and nodes of the overlay network are connected through ISPs that supports bandwidth reservations. The topology design problem is expressed as an optimization problem. Even though the design problem is related to the (in general NP-hard) quadratic assignment problem, it is shown that relatively simple heuristic algorithms can deliver results that are sometimes close to the optimal solution with little overhead.

In this work, we have considered a new hierarchical non-DHT based architecture for Peer-to-Peer (P2P) networks in which at each level of the hierarchy existing networks are all structured and each such network has the diameter of 1 overlay hop. Such low diameters have immense importance in designing very efficient data lookup algorithms. The mathematical model based on the Chinese Remainder Theorem has been used to define the neighborhood relations among peers to obtain the above-mentioned diameters. In this work, we present very efficient intra-group as well as inter-group data look up algorithms with O(1) time complexity exploiting the above mentioned low diameter features of the P2P system. Besides, we present very efficient algorithms related to peers joining with new and existing resource types.

The present paper proposes an architecture for a pure peer-to-peer communication system that is free from centralized coordination and knowledge. To meet this decentralization requirement the current paper focuses on a novel Overlay Discovery Algorithm which allows peers to connect to the network in an efficient and dynamic fashion. The system consists of three core modules which enable peers to meet, organize and communicate respectively. In addition, a series of simulation results is presented as a proof of concept for the Overlay Discovery Algorithm.

This paper presents a fast near linear run-time algorithm for deadline-satisfying packet forwarding and route lookup. This algorithm has been designed after a Constraint Resource Planning (CRP) methodology of approximation algorithm design. The algorithm uses scheduling and forwarding heuristics to produce near- optimal performance. These heuristics execute within a generic shell. In this paper we present the algorithm, the shell

Although Peer-to-Peer live video streaming over wireless mesh networks (WMNs) is considered a promising technology, some important challenges such as interference, mobility and limited available resources in gadgets (e.g. Smartphones and Tablets) may significantly reduce the perceived video quality. GREENIE and MATIN, in our previous studies, provided an efficient routing protocol in WMNs and a video streaming method based on random network coding (RNC), respectively. Therefore, their integration in the form of an enhanced framework, named GAZELLE, can considerably increase the video quality on these gadgets by decreasing the video distortion, dependency distortion, initial start-up delay and end-to-end delay. Findings using a precise simulation in OMNET?? show that GAZELLE noticeably outperforms other frameworks. GAZELLE not only decreases the imposed computational complexity and transmission overhead due to using RNC considerably, but it also efficiently routes video packets through those gadgets which does not require neither high battery energy sources nor high CPU power.

In recent years, Random Network Coding (RNC) has emerged as a promising solution for efficient Peer-to-Peer (P2P) video multicasting over the Internet. This probably refers to this fact that RNC noticeably increases the error resiliency and throughput of the network. However, high transmission overhead arising from sending large coefficients vector as header has been the most important challenge of the RNC. Moreover, due to employing the Gauss-Jordan elimination method, considerable computational complexity can be imposed on peers in decoding the encoded blocks and checking linear dependency among the coefficients vectors. In order to address these challenges, this study introduces MATIN which is a random network coding based framework for efficient P2P video streaming. The MATIN includes a novel coefficients matrix generation method so that there is no linear dependency in the generated coefficients matrix. Using the proposed framework, each peer encapsulates one instead of n coefficients entries into the generated encoded packet which results in very low transmission overhead. It is also possible to obtain the inverted coefficients matrix using a bit number of simple arithmetic operations. In this regard, peers sustain very low computational complexities. As a result, the MATIN permits random network coding to be more efficient in P2P video streaming systems. The results obtained from simulation using OMNET++ show that it substantially outperforms the RNC which uses the Gauss-Jordan elimination method by providing better video quality on peers in terms of the four important performance metrics including video distortion, dependency distortion, End-to-End delay and Initial Startup delay.

The scarcity of the radio channel is the main bottleneck toward maintaining the quality of service (QoS) in a mobile cellular network. As channel allocation schemes become more complex and computationally demanding, alternative computational models that include knowledge-based algorithms and provide the means for faster processing are becoming a topic of research interest. An efficient deterministic technique, capable of handling channel allocation problems, is introduced as an alternative. The proposed model utilizes the Global Positioning System (GPS) data for tracing the hosts’ likely movements within and across the cells and allocates the channels to the mobile devices accordingly. The allocation of the channels to the mobile hosts is deterministic in the sense that the decision of the channel allocation is based on the realistic data received from the GPS about the hosts’ movements. The performance of the proposed technique has been evaluated by conducting the simulation experi...

Computation in the mobile grid nodes under the cellular network environment requires an efficient management of wireless channels along with the user mobility. Due to random movement of the mobile devices, the load over the cells in terms of initiation of new computation or carryover computation (handoff) may vary dynamically. This may result in non-availability of free channels for Inter-task communication leading in the drop of carryover computation or to initiate the new computation in the current cell. The proposed work designs a model by instigating substantive cooperation among underutilized and the overloaded cells, considering importance to the frequency reuse and assigning priority to the on-going computation in the computational mobile grid. The model seeks cooperation by grouping the cells in different sizes to reduce the blocking and dropping of the computation. Blocking of the communication is very serious in computational mobile grid environment as the drop may result ...

The existing peer-to-peer networks have several problems such as fake content distribution, free riding, white-washing and poor search scalability, lack of a robust trust model and absence of user privacy protection mechanism. Although, several trust management and semantic community-based mechanisms for combating free riding and distribution of malicious contents have been proposed by some researchers, most of these schemes lack scalability due to their high computational, communication and storage overhead. This paper presents a robust trust management scheme for P2P networks that utilizes topology adaptation by constructing an overlay of trusted peers where the neighbors are selected based on their trust ratings and content similarities. While increasing the search efficiency by intelligently exploiting the formation of semantic community structures by topology adaptation among the trustworthy peers, the scheme provides the users a very high level of privacy protection of their usage and consumption patterns of network resources. Simulation results demonstrate that the proposed scheme provides efficient searching to good peers while penalizing the malicious peers by increasing their search times as the network topology stabilizes.

One major benefit of named-data networking (NDN) is its potential to control network load by leveraging in-network caching and request aggregation. Both the network operator and consumers benefit from these features, as operating costs are reduced and quality-of-experience is increased. However, request aggregation, combined with NDN's loop prevention mechanisms, can create denial-of-service (DoS) against client interests (intentionally and unintentionally) by clients employing multicast forwarding. In this paper, we discuss this problem and propose three increasingly efficient solutions to address the problem; our arguments are backed by simulation and numerical analyses.

creates new opportunities to save costs by converging data and telephone services. The primary question of our study is whether emerging metropolitan networks can meet the QoS requirements necessary to connect GSM and UMTS base stations. These requirements on delay, jitter, and loss are significantly more stringent than the ones for VoIP and have to be met at the presence of bursty cross traffic. Therefore, we have probed ETH's campus network which spans the metropolitan area of Zurich with traffic comparable to encapsulated E1 traffic from base stations and have measured perceived QoS. Our findings show that the campus network generally meets the QoS requirements. However, the perceived QoS degrades with increasing network utilization. To further investigate the impact of the configuration of Ethernet switches on perceived QoS, we have conducted a simulation study. The results show that the perceived QoS is better when switch buffers are limited to small sizes of 1 MB compared to setups where the number of frames in the buffer is limited. From these results we infer that metropolitan Gigabit Ethernets are well suited for connecting GSM and UMTS base stations.

Path probing is essential to maintaining an efficient overlay network topology. However, the cost of complete probing can be as high as ¢ ¤£ ¦¥ ¨ § © , which is prohibitive in large- scale overlay networks. Recently we proposed a method that trades probing overhead for inference accuracy in sparse networks such as the Internet. The method uses physical path information to infer path quality for all of the ¥ £ ¦¥ © overlay paths, while actually probing only a subset of the paths. In this paper we propose and evaluate a distributed approach to implementing this method. We describe a minimum diameter, link-stress bounded overlay spanning tree, which is used to collect and disseminate path quality information. All nodes in the tree collaborate to infer the quality of all paths. Simulation results show this approach can achieve a high-level of inference accuracy while reducing probing overhead and balancing link stress on the spanning tree.

This paper describes Service Clouds, a distributed infrastructure designed to facilitate rapid prototyping and deployment of services that enhance communication performance, robustness, and security. The infrastructure combines adaptive middleware functionality with an overlay network substrate in order to support dynamic instantiation and reconfiguration of services. The Service Clouds architecture includes a collection of lowlevel facilities that can be either invoked directly by applications or used to compose more complex services. After describing the Service Clouds architecture, we present results of two experimental case studies conducted on the PlanetLab Internet testbed, the first to improve throughput of bulk data transfer, and the second to enhance the robustness of multimedia streaming.

In pervasive computing environments, conditions are highly variable and resources are limited. In order to meet the needs of applications, systems must adapt dynamically to changing situations. Since adaptation at one system layer may be insufficient, crosslayer, or vertical approaches to adaptation may be needed. Moreover, adaptation in distributed systems often requires horizontal cooperation among hosts. This cooperation is not restricted to the source and destination(s) of a data stream, but might also include intermediate hosts in an overlay network or mobile ad hoc network. We refer to this combined capability as universal adaptation. We contend that the model defining interaction between adaptive middleware and the operating system is critical to realizing universal adaptation. We explore this hypothesis by evaluating the Kernel-Middleware eXchange (KMX), a specific model for crosslayer, cross-system adaptation. We present the KMX architecture and discuss its potential role in supporting universal adaptation in pervasive computing environments. We then describe a prototype implementation of KMX and show results of an experimental case study in which KMX is used to improve the quality of video streaming to mobile nodes in a hybrid wired-wireless network.

Use of multiple paths between node pairs can enable an overlay network to bypass Internet link failures. Selecting high quality primary and backup paths is challenging, however. To maximize communication reliability, an overlay multipath routing protocol must account for both the failure probability of a single path and link sharing among multiple paths. We propose a practical solution that exploits physical topology information and end-to-end path quality measurement results to select high quality path pairs. Simulation results show the proposed approach is effective in achieving higher multipath reliability in overlay networks at reasonable communication cost.

Path probing is essential to maintaining an efficient overlay network topology. However, the cost of a full-scale probing is as high as ¢ ¤£ ¦¥ ¨ § © , which is prohibitive in large-scale overlay networks. Several methods have been proposed to reduce probing overhead, although at a cost in terms of probing completeness. In this paper, an orthogonal solution is proposed that trades probing overhead for estimation accuracy in sparse networks such as the Internet. The proposed solution uses network-level path composition information (for example, as provided by a topology server) to infer path quality without full-scale probing. The inference metrics include latency, loss rate and available bandwidth. This approach is used to design several probing algorithms, which are evaluated through analysis and simulation. The results show that the proposed method can significantly reduce probing overhead while providing bounded quality estimations for all ¥ £ ¦¥ © overlay paths. The solution is well suited to medium-scale overlay networks in the Internet. In other environments, it can be combined with extant probing algorithms to further improve performance. © , the latency of £ ¤ is © , and the latency of ¤ is © . Then we have the following linear equations:

Path probing is essential to maintaining an efficient overlay network topology. However, the cost of complete probing can be as high as ¢ ¤£ ¦¥ ¨ § © , which is prohibitive in large- scale overlay networks. Recently we proposed a method that trades probing overhead for inference accuracy in sparse networks such as the Internet. The method uses physical path information to infer path quality for all of the ¥ £ ¦¥ © overlay paths, while actually probing only a subset of the paths. In this paper we propose and evaluate a distributed approach to implementing this method. We describe a minimum diameter, link-stress bounded overlay spanning tree, which is used to collect and disseminate path quality information. All nodes in the tree collaborate to infer the quality of all paths. Simulation results show this approach can achieve a high-level of inference accuracy while reducing probing overhead and balancing link stress on the spanning tree.

In pervasive computing environments, conditions are highly variable and resources are limited. In order to meet the needs of applications, systems must adapt dynamically to changing situations. Since adaptation at one system layer may be insufficient, crosslayer, or vertical approaches to adaptation may be needed. Moreover, adaptation in distributed systems often requires horizontal cooperation among hosts. This cooperation is not restricted to the source and destination(s) of a data stream, but might also include intermediate hosts in an overlay network or mobile ad hoc network. We refer to this combined capability as universal adaptation. We contend that the model defining interaction between adaptive middleware and the operating system is critical to realizing universal adaptation. We explore this hypothesis by evaluating the Kernel-Middleware eXchange (KMX), a specific model for crosslayer, cross-system adaptation. We present the KMX architecture and discuss its potential role in supporting universal adaptation in pervasive computing environments. We then describe a prototype implementation of KMX and show results of an experimental case study in which KMX is used to improve the quality of video streaming to mobile nodes in a hybrid wired-wireless network.

Use of multiple paths between node pairs can enable an overlay network to bypass Internet link failures. Selecting high quality primary and backup paths is challenging, however. To maximize communication reliability, an overlay multipath routing protocol must account for both the failure probability of a single path and link sharing among multiple paths. We propose a practical solution that exploits physical topology information and end-to-end path quality measurement results to select high quality path pairs. Simulation results show the proposed approach is effective in achieving higher multipath reliability in overlay networks at reasonable communication cost.

Path probing is essential to maintaining an efficient overlay network topology. However, the cost of a full-scale probing is as high as O(n 2 ), which is prohibitive in large-scale overlay networks. Several methods have been proposed to reduce probing overhead, although at a cost in terms of probing completeness. In this paper, an orthogonal solution is proposed that trades probing overhead for estimation accuracy in sparse networks such as the Internet. The proposed solution uses network-level path composition information (for example, as provided by a topology server) to infer path quality without full-scale probing. The inference metrics include latency, loss rate and available bandwidth. This approach is used to design several probing algorithms, which are evaluated through analysis and simulation. The results show that the proposed method can significantly reduce probing overhead while providing bounded quality estimations for all n × (n -1) overlay paths. The solution is well suited to medium-scale overlay networks in the Internet. In other environments, it can be combined with extant probing algorithms to further improve performance.

We recently introduced Service Clouds, a distributed infrastructure designed to facilitate rapid prototyping and deployment of autonomic communication services. In this paper, we propose a model that extends Service Clouds to the wireless edge of the Internet. This model, called Mobile Service Clouds, enables dynamic instantiation, composition, configuration, and reconfiguration of services on an overlay network to support mobile computing. We have implemented a prototype of this model and applied it to the problem of dynamically instantiating and migrating proxy services for mobile hosts. We conducted a case study involving data streaming across a combination of PlanetLab nodes, local proxies, and wireless hosts. Results are presented demonstrating the effectiveness of the prototype in establishing new proxies and migrating their functionality in response to node failures.

This paper addresses the problem of mapping software services onto an overlay network, specifically, the probing to locate suitable nodes on which to instantiate or configure data processing operators. We propose a distributed algorithm, called Dynamis, that can improve existing probing algorithms. Experimental results on the PlanetLab testbed show that Dynamis can dramatically reduce probing overhead while producing high-quality services.

This paper describes Service Clouds, a distributed infrastructure designed to facilitate rapid prototyping and deployment of adaptive communication services. The infrastructure combines adaptive middleware functionality with an overlay network substrate in order to support dynamic instantiation and reconfiguration of services. The Service Clouds architecture includes a collection of low-level facilities that can be invoked directly by applications or used to compose more complex services. After describing the Service Clouds architecture, we present results of experimental case studies conducted on the PlanetLab Internet testbed alone and a mobile computing testbed.

Path probing is essential to maintaining an efficient overlay network topology. However, the cost of a full-scale probing is as high as O(n 2 ), which is prohibitive in large-scale overlay networks. Several methods have been proposed to reduce probing overhead, although at a cost in terms of probing completeness. In this paper, an orthogonal solution is proposed that trades probing overhead for estimation accuracy in sparse networks such as the Internet. The proposed solution uses network-level path composition information (for example, as provided by a topology server) to infer path quality without full-scale probing. The inference metrics include latency, loss rate and available bandwidth. This approach is used to design several probing algorithms, which are evaluated through extensive simulation. The results show that the proposed method can reduce probing overhead significantly while providing bounded quality estimations for all of the n • (n À 1) overlay paths. The solution is well suited to medium-scale overlay networks in the Internet. In other environments, it can be combined with extant probing algorithms to further improve performance.

The metrics play increasingly fundamental role in the design, development, deployment and operation of telecommunication systems. Despite their importance, the studies of metrics are usually limited to a narrow area or a well-defined objective. Our study aims to more broadly survey the metrics that are commonly used for analyzing, developing and managing telecommunication networks in order to facilitate understanding of the current metrics landscape. The metrics are simple abstractions of systems, and they directly influence how the systems are perceived by different stakeholders. However, defining and using metrics for telecommunication systems with ever increasing complexity is a complicated matter which has not been so far systematically and comprehensively considered in the literature. The common metrics sources are identified, and how the metrics are used and selected is discussed. The most commonly used metrics for telecommunication systems are categorized and presented as energy and power metrics, quality-of-service metrics, quality-of-experience metrics, security metrics, and reliability and resilience metrics. Finally, the research directions and recommendations how the metrics can evolve, and be defined and used more effectively are outlined.

Named Data Networking (NDN), a data-centric enabled-cache architecture, as one of the candidates for the future Internet, has the potential to overcome many of the current Internet difficulties (e.g., security, mobility, multicasting). Influenced by using cache in intermediate equipment, NDN has gained attention as a prominent method of Internet content sharing. Managing the NDN caches and reducing the cache redundancy are the important goals in this paper. Our main contribution in this research is toward caching optimization in comparison with betweenness probabilistic in-network caching strategy. Therefore, with respect to combined impacts of long-term centrality-based metric and Linear Weighted Moving Average (LWMA) of short-term parameters such as user incoming pending requests and unique outgoing hit requests on caching management, a flexible probability caching strategy is proposed. Moreover, a simple Randomized-SVD approach is applied to combine averaged short-term and long-term metrics. The output of this data-fusion algorithm is used to allocate a proper probability to the caching strategy. Evaluation results display an increase in the hit ratios of NDN routers' content-stores for the proposed method. In addition, the producer's hit ratio and the Interest-Data Round Trip Time, compared to the betweenness scheme, is decreased.

Big data is developing quickly, combining industrial techniques and scholarly research to address the difficulties of organising and comprehending large-scale datasets. This dissertation investigates how the AMBER software's Molecular Dynamics simulations can benefit from the increased processing power provided by High-Performance Mobile Cloud Computing (HPMCC). Fortunately, demonstrates a way to more effectively divide computational demands through parallel processing with the Message Passing Interface (MPI) by establishing connections between laptops and virtual machines over a mobile cloud infrastructure. This approach provides a scalable and affordable replacement for conventional supercomputers and speeds up processing. Furthermore, this research addresses security issues with Single Sign-On (SSO) technologies, showcasing cloud computing's capacity to manage massive data demands, especially in scientific research.

In this paper, we introduce a routing solution called "Landmark Overlays for Urban Vehicular Routing Environments" (LOUVRE), an approach that efficiently builds a landmark overlay network on top of an urban topology. We define urban junctions as overlay nodes and create an overlay link if and only if the traffic density of the underlying network guarantees the multi-hop vehicular routing between the two overlay nodes. LOUVRE contains a distributed traffic density estimation scheme which is used to evaluate the existence of an overlay link. Then, efficient routing is performed on the overlay network, guaranteeing a correct delivery of each packet. We evaluate LOUVRE against the benchmark routing protocols of GPSR and GPCR and show that LOUVRE performs higher in packet delivery and achieves lower hop count.

e introduce a routing solution called landmark overlays for urban vehicular routing environments (LOUVRE), an approach that efficiently builds a landmark overlay network on top of an urban topology. We define urban junctions as overlay nodes and create an overlay link if and only if the traffic density of the underlying network guarantees the multihop vehicular routing between the two overlay nodes. LOUVRE contains a distributed traffic density estimation scheme that is used to evaluate the existence of an overlay link. Then, efficient routing is performed on the overlay network, guaranteeing a correct delivery of each packet. We evaluate LOUVRE against the benchmark routing protocols of greedy perimeter stateless routing (GPSR) and greedy perimeter coordinator routing (GPCR) and show that LOUVRE performs higher in packet delivery and achieves lower hop count. The ever-growing spread of vehicles and roadside traffic monitors with the advancement of navigation systems and the low cost of wireless network devices provide incentives for car manufacturers to equip vehicles with real-time traffic reports, promising peer-to-peer (P2P) applications, and externally driven services to vehicles. However, for these applications and services to materialize, there is a need for standards of ubiquitous high-speed communications and homogeneous communication interfaces among different automotive manufacturers. For this purpose, the Intelligent Transportation Systems (ITS) have proposed the wireless access in vehicular environments (WAVE) standards that define an architecture that collectively enables vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) wireless communications . In order to enable multihop wireless vehicular communications, vehicles are equipped with WAVE devices and interconnected with one other to form a vehicular ad hoc network (VANET), which is a particularly challenging class of mobile ad hoc networks (MANETs). VANETs are distributed, self-organizing networks built from moving vehicles, and are thus characterized by very high speed, a strong nonuniform distribution of vehicles, and a

Multipath overlay routing technologies are seen as alternative solutions for VoIP because they inherit path diversity from peer-to-peer overlay networks. We discuss and compare the performances of two relay path selection approaches proposed for VoIP overlay systems through extensive simulations. We propose a new method for relay path computation that takes into account both path disjointness and other network quality factors (such as packet delay or loss). We further apply our method in different overlay network scenarios by varying the supernode distribution. It is found that there is a considerable improvement of path performance when relaying traffic through highly connected ASs using the new method.

The Secure Internet Indirection Infrastructure (Secure-i 3 ) is a proposal for a flexible and secure overlay network that, if universally deployed, would effectively block a number of denial-of-service problems in the Internet. The Host Identity Protocol (HIP), on the other hand, is a proposal for deploying opportunistic, IPsec based end-to-end security, allowing any hosts to communicate in a secure way through the Internet. In this paper, we explore various possibilities for combining ideas from Secure-i 3 and HIP, thereby producing an architecture that is more efficient and secure than Secure-i 3 and more flexible and denial-of-service resistant than HIP.

The Secure Internet Indirection Infrastructure (Secure-i 3 ) is a proposal for a flexible and secure overlay network that, if universally deployed, would effectively block a number of denial-of-service problems in the Internet. The Host Identity Protocol (HIP), on the other hand, is a proposal for deploying opportunistic, IPsec based end-to-end security, allowing any hosts to communicate in a secure way through the Internet. In this paper, we explore various possibilities for combining ideas from Secure-i 3 and HIP, thereby producing an architecture that is more efficient and secure than Secure-i 3 and more flexible and denial-of-service resistant than HIP.

»The fact that we live in a time when clouds can be calculated in all their randomness thanks to Mandelbrot's fractals and then appear on a screen as calculated, unfilmed images distinguishes the present from any previous time.« (Kittler 2002:37)

We propose a new scheme for content distribution of large files that is based on network coding. With network coding, each node of the distribution network is able to generate and transmit encoded blocks of information. The randomization introduced by the coding process eases the scheduling of block propagation, and, thus, makes the distribution more efficient. This is particularly important in large unstructured overlay networks, where the nodes need to make block forwarding decisions based on local information only. We compare network coding to other schemes that transmit unencoded information (i.e. blocks of the original file) and, also, to schemes in which only the source is allowed to generate and transmit encoded packets. We study the performance of network coding in heterogeneous networks with dynamic node arrival and departure patterns, clustered topologies, and when incentive mechanisms to discourage free-riding are in place. We demonstrate through simulations of scenarios of practical interest that the expected file download time improves by more than 20-30% with network coding compared to coding at the server only and, by more than 2-3 times compared to sending unencoded information. Moreover, we show that network coding improves the robustness of the system and is able to smoothly handle extreme situations where the server and nodes leave the system.

The main goals of fifth generation (5G) systems are to significantly increase the network
capacity and to support new 5G service requirements. Ultra network densification with small cells is
among the key pillars for 5G evolution. The inter-small-cell 5G backhaul network involves massive data
traffic. Hence, it is important to have a centralized, efficient multi-hop routing protocol for backhaul
networks to manage and speed up the routing decisions among small cells, while considering the 5G service
requirements. This paper proposes a parallel multi-hop routing protocol to speed up routing decisions in
5G backhaul networks. To this end, we study the efficiency of utilizing the parallel platforms of cloud
computing and high-performance computing (HPC) to manage and speed up the parallel routing protocol
for different communication network sizes and set recommendations for utilizing cloud resources to adopt
the parallel protocol. Our numerical results indicate that the HPC parallel implementation outperforms the
cloud computing implementation, in terms of routing decision speed-up and scalability to large network
sizes. In particular, for a large network size with 2048 nodes, our HPC implementation achieves a routing
speed-up of 37x. However, the best routing speed-up achieved using our cloud computing implementation
is 15.5x, and is recorded using one virtual machine (VM) for a network size of 1024 nodes. In summary,
there is a trade-off between a better performance for HPC vs. flexible resources of cloud computing. Thus,
choosing best fit platform for 5G routing protocols depends on the deployment scenarios at 5G core or edge
network.

Peer to peer (P2P) networks have using commonly used for tasks such as file sharing or file distribution, and for building distributed applications in large scale network. Their performance measures are generally based on simulation methods software such as NS-2, P2PSim, OpenNet, etc. Hence, the absence of a validation of the simulation model is a critical issue. In this paper, we propose a new analytical model derived from (8), to evaluate the performance of HPM protocol (hierarchical Peer-to-Peer model). Performance is done principally in terms of total download time of requested resources in the P2P network, and then we analyze the impact of various parameters associated with the heterogeneity of nodes.