1,720,970 research outputs found
NePA TesT: Network Protocol and Application Testing Toolchain for Community Networks
No full textA Community Network (CN) is a bottom-up network infrastructure that interconnects communities of people and represents a promising and successful networking model. The more people join a CN, the higher is the demand for a wider range of community services and the need for scalable network protocols. CN designers and passionates hence require adequate frameworks to develop and test different technical solutions, that must reproduce realistic environments and allow a rapid prototyping and deployment. We propose a full-comprehensive framework that can be used to develop new protocols and applications both in a flexible and portable manner. NePA TesT (Network Protocols and Applications Testing Toolchain) is based on the Mininet emulator enriched with: a library capable of creating random synthetic topologies with the most up to date realistic topology generators, a data set with topologies extracted from real world CNs, and powerful extensions to dynamically run and control the emulated scenarios. This paper will analyse and document each component and show how NePA TesT can be used in two realistic application scenarios.A Community Network (CN) is a bottom-up network infrastructure that interconnects communities of people and represents a promising and successful networking model. The more people join a CN, the higher is the demand for a wider range of community services and the need for scalable network protocols. CN designers and passionates hence require adequate frameworks to develop and test different technical solutions, that must reproduce realistic environments and allow a rapid prototyping and deployment. We propose a full-comprehensive framework that can be used to develop new protocols and applications both in a flexible and portable manner. NePA TesT (Network Protocols and Applications Testing Toolchain) is based on the Mininet emulator enriched with: a library capable of creating random synthetic topologies with the most up to date realistic topology generators, a data set with topologies extracted from real world CNs, and powerful extensions to dynamically run and control the emulated scenarios. This paper will analyse and document each component and show how NePA TesT can be used in two realistic application scenarios
On the Use of Eigenvector Centrality for Cooperative Streaming
No full textThe timely and efficient cooperative distribution of a streamlined content in a communication network is a key feature for many applications and services. One of the unsolved problems is the assignment of transmission rates to nodes given the constraints imposed by the topology, so that all nodes receive the stream with the minimal global use of resources. This paper addresses the problem exploiting the notion of eigenvector centrality. It shows that the problem can be solved efficiently in a distributed way if every node is aware of the full network topology and that in certain cases only local information on the network graph is sufficient.The timely and efficient cooperative distribution of a streamlined content in a communication network is a key feature for many applications and services. One of the unsolved problems is the assignment of transmission rates to nodes, given the constraints imposed by the topology, so that all nodes receive the stream with the minimal global use of resources. This letter addresses the problem exploiting the notion of eigenvector centrality. It shows that the problem can be solved efficiently in a distributed way if every node is aware of the full network topology and that in certain cases only local information on the network graph is sufficient
Improving P2P Streaming in Community-Lab Through Local Strategies
No full textDistributing live streaming in Wireless Community Networks (WCNs) is a service with a high added value; however, cloud-based streaming, as commonly used in the Internet, does not fit well the architecture of WCNs, which often have restricted access to the Internet. Modern WCNs, instead, can have a good internal connectivity with high bandwidth. A P2P approach is thus well matched for streaming in WCNs. This paper presents experimental results obtained with PeerStreamer running on top of Community-Lab, a test-bed realized by the CONFINE EU Project for the experimentation of novel protocols in community networks. The experiments highlight relevant differences between a WCN and the Internet, and we propose strategies that can be implemented on all the peers or even only locally on the source to improve the streaming quality. These strategies are based on simple heuristics and can be activated dynamically when the streaming quality degrades below a given threshold
Live P2P streaming in CommunityLab: Experience and Insights
No full textWireless Community Networks (WCNs) are flourishing as a means of providing Internet access, but most of all as an alternative, bottom-up approach to reduce the digital divide and empower the users with control on their network. Video streaming and conferencing are among the most resource hungry and critical networked applications, and their support on WCNs is fundamental, but difficult as Wireless Community Network (WCN) environments are normally less resource-rich than the traditional Internet. This work presents an initial analysis of an experimental activity with Peer Streamer, a P2P video streaming platform, on the Community-Lab, the WCN testbed of the EU FIRE project CONFINE. The results we present shed light on several different aspects, some good, some other less, of video streaming on WCNs. The experiments highlight the feasibility of P2P video streaming, but they also show that the streaming platform must be tailored ad-hoc for the WCN itself to be able to fully adapt and exploit its features and overcome its limitations. On the other hand, the experiments also show that Community-Lab is not yet fully representative of a WCN, and specifically of those that participate in CONFINE
Optimized Cooperative Streaming in Wireless Mesh Networks
Full text linkPeer-to-peer video streaming is a valuable technique to reduce the overhead produced by centralized and unicast-based video streaming. Key to the efficiency of a peer-topeer approach is the optimization of the logical distribution topology (the overlay with respect to the underlying network, the underlay). This work studies peer-to-peer streaming in wireless mesh networks for which the underlay is known. We propose an optimized, cross-layer approach to build the peer-to-peer distribution overlay minimizing the impact on the underlay. We design an optimal strategy, which is proven to be NP-complete, and thus not solvable with a distributed, light weight protocol. The optimal strategy is relaxed exploiting the knowledge of the betweenness centrality of the underlay nodes, obtaining two easily implementable solutions applicable to any link-state routing protocol. Simulation and emulation results (experimenting with real applications on a network emulated with the Mininet framework) support the theoretical findings, showing that the relaxed implementations are reasonably close to the optimal solution, and provide vast gains compared to the traditional overlay topology based on Erdös-Rényi models that a peer-to-peer application would build.Peer-to-peer video streaming is a valuable technique to reduce the overhead produced by centralized and unicast-based video streaming. Key to the efficiency of a peer-to-peer approach is the optimization of the logical distribution topology (the overlay with respect to the underlying network, the underlay). This work studies peer-to-peer streaming in wireless mesh networks for which the underlay is known. We propose an optimized, cross-layer approach to build the peer-to-peer distribution overlay minimizing the impact on the underlay. We design an optimal strategy, which is proven to be NP-complete, and thus not solvable with a distributed, light weight protocol. The optimal strategy is relaxed exploiting the knowledge of the betweenness centrality of the underlay nodes, obtaining two easily implementable solutions applicable to any link-state routing protocol. Simulation and emulation results (experimenting with real applications on a network emulated with the Mininet framework) support the theoretical findings, showing that the relaxed implementations are reasonably close to the optimal solution, and provide vast gains compared to the traditional overlay topology based on Erdos-Renyi models that a peer-to-peer application would build
On the Properties of Infective Flooding in Low-Duty-Cycle Networks
Full text linkBroadcasting information in a network is an important function in networking applications. In some networks, as wireless sensor networks or some ad-hoc networks it is so essential as to dominate the performance of the entire system. Exploiting some recent results based on the computation of the eigenvector centrality of nodes in the network graph and classical dynamic diffusion models on graphs, this paper derives a novel theoretical framework for efficient information broadcasting in mesh networks with low duty-cycling without the need to build a distribution tree. The model provides lower and upper stochastic bounds with high probability. We show that the lower bound is very close to the theoretical optimum and that a preliminary implementation provides results that are very close to the lower bound on classical graph models
Optimizing MRAI on large scale BGP networks: An emulation-based approach
Full text linkModifying protocols that pertain to global Internet control is extremely challenging, because experimentation is almost impossible and both analytic and simulation models are not detailed and accurate enough to guarantee that changes will not affect negatively the Internet. Federated testbeds like the ones offered by the Fed4FIRE+ project offer a different solution: off-line Internet-scale experiments with thousands of Autonomous Systems (ASs). This work exploits Fed4FIRE+ for a large-scale experimental analysis of Border Gateway Protocol (BGP) convergence time under different hypotheses of Minimum Route Advertisement Interval (MRAI) setting, including an original proposal to improve its management by dynamically setting MRAI based on the topological position of the ASs in relation to the specific route being advertised with the UPDATE messages. MRAI is a timer that regulates the frequency of successive UPDATE messages sent by a BGP router to a specific peer for a given destination. Its large default value significantly slows down convergence after path changes, but its uncoordinated reduction can trigger storms of UPDATE messages, and set off unstable behaviors known as route flapping. The work is based on standard-compliant modifications of the BIRD BGP daemon and shows the tradeoffs between convergence time and signaling overhead with different management techniques
Keep It Fresh: Reducing the Age of Information in V2X Networks
Full text linkThe freshness of information is of the utmost importance in many contexts, including V2X networks and applications. One measure of this metric is the Age of Information (AoI), a notion recently introduced and explored by several authors, often with specific reference to vehicular networks. With this work, we explore the possibility of reducing the AoI of multi-hop information flooding in V2X networks exploiting the properties of the Eigenvector Centrality (EvC) of nodes in the topology, and the possibility that each node computes it exploiting only local information and very easy computations, so that each node can autonomously adapt its own networking parameters to redistribute information more efficiently. Starting from theoretical bounds and results, we explore how they hold in urban-constrained topologies and compare the AoI achieved exploiting EvC with the AoI achievable without this optimization of the nodes' behavior. Simulation results show a meaningful improvement without using additional resources and without the need of any global coordination
Improving P2P streaming in Wireless Community Networks
Full text linkAbstract Wireless Community Networks (WCNs) are bottom-up broadband networks empowering people with their on-line communication means. Too often, however, services tailored for their characteristics are missing, with the consequence that they have worse performance than what they could. We present here an adaptation of an Open Source P2P live streaming platform that works efficiently, and with good application-level quality, over WCNs. \WCNs links are normally symmetric (unlike standard ADSL access), and a WCN topology is local and normally flat (contrary to the global Internet), so that the P2P overlay used for video distribution can be adapted to the underlaying network characteristics. We exploit this observation to derive overlay building strategies that make use of cross-layer information to reduce the impact of the P2P streaming on the WCN while maintaining good application performance. We experiment with a real application in real WCN nodes, both in the Community-Lab provided by the CONFINE EU Project and within an emulation framework based on Mininet, where we can build larger topologies and interact more efficiently with the mesh underlay, which is unfortunately not accessible in Community-Lab. The results show that, with the overlay building strategies proposed, the P2P streaming applications can reduce the load on the WCN to about one half, also equalizing the load on links. At the same time the delivery rate and delay of video chunks are practically unaffected
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