LUNES: Agent-based Simulation of P2P Systems (Extended Version)

We present LUNES, an agent-based Large Unstructured NEtwork Simulator, which allows to simulate complex networks composed of a high number of nodes. LUNES is modular, since it splits the three phases of network topology creation, protocol simulation and performance evaluation. This permits to easily integrate external software tools into the main software architecture. The simulation of the interaction protocols among network nodes is performed via a simulation middleware that supports both the sequential and the parallel/distributed simulation approaches. In the latter case, a specific mechanism for the communication overhead-reduction is used; this guarantees high levels of performance and scalability. To demonstrate the efficiency of LUNES, we test the simulator with gossip protocols executed on top of networks (representing peer-to-peer overlays), generated with different topologies. Results demonstrate the effectiveness of the proposed approach.Comment: Proceedings of the International Workshop on Modeling and Simulation of Peer-to-Peer Architectures and Systems (MOSPAS 2011). As part of the 2011 International Conference on High Performance Computing and Simulation (HPCS 2011

Highly intensive data dissemination in complex networks

This paper presents a study on data dissemination in unstructured Peer-to-Peer (P2P) network overlays. The absence of a structure in unstructured overlays eases the network management, at the cost of non-optimal mechanisms to spread messages in the network. Thus, dissemination schemes must be employed that allow covering a large portion of the network with a high probability (e.g.~gossip based approaches). We identify principal metrics, provide a theoretical model and perform the assessment evaluation using a high performance simulator that is based on a parallel and distributed architecture. A main point of this study is that our simulation model considers implementation technical details, such as the use of caching and Time To Live (TTL) in message dissemination, that are usually neglected in simulations, due to the additional overhead they cause. Outcomes confirm that these technical details have an important influence on the performance of dissemination schemes and that the studied schemes are quite effective to spread information in P2P overlay networks, whatever their topology. Moreover, the practical usage of such dissemination mechanisms requires a fine tuning of many parameters, the choice between different network topologies and the assessment of behaviors such as free riding. All this can be done only using efficient simulation tools to support both the network design phase and, in some cases, at runtime

Rumor Spreading with No Dependence on Conductance

National Science Foundation (U.S.) (CCF-0843915

On the Complexity of Asynchronous Gossip

In this paper, we study the complexity of gossip in an asynchronous, message-passing fault-prone distributed system. In short, we show that an adaptive adversary can significantly hamper the spreading of a rumor, while an oblivious adversary cannot. In the latter case, we present three randomized algorithms for achieving gossip, each offering a different trade-off between time and message complexity. We then show how to use these gossip algorithms to develop message-efficient asynchronous (randomized) consensus protocols

Studio del free riding nella disseminazione per mezzo di gossip

Questa tesi presenta uno studio sugli effetti del fenomeno del free riding (nodi che beneficiano delle informazioni scambiate da altri nodi senza offrire nulla in cambio al network) sulle prestazioni della disseminazione tramite protocolli di gossip all'interno di network P2P. Grazie ad un apposito strumento per la simulazione di overlay network (LUNES), vengono compiute simulazioni su un determinato caso di studio per stabilire l'effetto sulle performance di coverage e overhead ratio in condizioni dove il numero di free rider è stabilito esclusivamente dalla persona che conduce i test. In seguito sono sviluppati meccanismi per la determinazione dei nodi free rider che rispondono a criteri adattivi, dipendenti di volta in volta da caratteristiche quali il Time-to-Live dei messaggi da inviare, la posizione del nodo nel grafo. Vengono poi effettuate ulteriori simulazioni su questi nuovi meccanismi adattivi e i risultati messi a confronto con quelli del precedente studio sul meccanismo stabile, al fine di comprendere come una distribuzione non puramente randomica nello spazio e costante nel tempo dei free rider ha effetto sulle suddette performance

Controlling gossip protocol infection pattern using adaptive fanout

Proceedings - International Conference on Distributed Computing Systems665-674PICS