Spectral Graph Forge: Graph Generation Targeting Modularity

Community structure is an important property that captures inhomogeneities common in large networks, and modularity is one of the most widely used metrics for such community structure. In this paper, we introduce a principled methodology, the Spectral Graph Forge, for generating random graphs that preserves community structure from a real network of interest, in terms of modularity. Our approach leverages the fact that the spectral structure of matrix representations of a graph encodes global information about community structure. The Spectral Graph Forge uses a low-rank approximation of the modularity matrix to generate synthetic graphs that match a target modularity within user-selectable degree of accuracy, while allowing other aspects of structure to vary. We show that the Spectral Graph Forge outperforms state-of-the-art techniques in terms of accuracy in targeting the modularity and randomness of the realizations, while also preserving other local structural properties and node attributes. We discuss extensions of the Spectral Graph Forge to target other properties beyond modularity, and its applications to anonymization

PartyHub - A PeerStreamer Conference Application

Video conferencing is still a lively research field, and for both personal and business applications it is reasonable to expect that the interest in conferencing services will grow in the future. However, available tools lack of scalability and flexibility features and the more widespread ones have proven to be a possible threat for our privacy. This technical report focuses on the design and development of PartyHub, an open source peer-to-peer conferencing platform, entirely customizable, distributed and privacy aware. This goal can be achieved porting a peer-to-peer live streaming platform, PeerStreamer [1] to the video conferencing context. In this report we document the test performed in order to verify the suitability of this idea and the future steps and challenges needed to develop PartyHub

Distributed live streaming on mesh networks

Internet is evolving in both its structure and usage patterns; this work addresses two trends: i) the increasing popularity and the related generated traffic of media streaming applications and ii) the emerging of network portions following different philosophies from the rest of the internet and being characterized by a mesh topology, such as Community Networks. This thesis presents a modeling for decentralized live streaming for mesh networks based on graph theory, considering the different inter-dependent network abstractions involved. It proposes optimization strategies based on popular centrality metrics, such as betweenness and PageRank. Results on real-world datasets validate the theoretical work and the derived optimizing strategies are implemented in open-source streaming platforms

On the Properties of Infective Flooding in Low-Duty-Cycle Networks

Broadcasting 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

NePA TesT: Network Protocol and Application Testing Toolchain for Community Networks

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.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

NePA TesT: network protocol and application testing toolchain for community networks

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

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 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

Optimized Cooperative Streaming in Wireless Mesh Networks

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-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