283 research outputs found
Monitoring Challenges and Approaches for P2P File-Sharing Systems
Since the release of Napster in 1999, P2P file-sharing has enjoyed a dramatic rise in popularity. A 2000 study by Plonka on the University of Wisconsin campus network found that file-sharing accounted for a comparable volume of traffic to HTTP, while a 2002 study by Saroiu et al. on the University of Washington campus network found that file-sharing accounted for more than treble the volume of Web traffic observed, thus affirming the significance of P2P in the context of Internet traffic. Empirical studies of P2P traffic are essential for supporting the design of next-generation P2P systems, informing the provisioning of network infrastructure and underpinning the policing of P2P systems. The latter is of particular significance as P2P file-sharing systems have been implicated in supporting criminal behaviour including copyright infringement and the distribution of illegal pornograph
Ricci Curvature of the Internet Topology
Analysis of Internet topologies has shown that the Internet topology has
negative curvature, measured by Gromov's "thin triangle condition", which is
tightly related to core congestion and route reliability. In this work we
analyze the discrete Ricci curvature of the Internet, defined by Ollivier, Lin,
etc. Ricci curvature measures whether local distances diverge or converge. It
is a more local measure which allows us to understand the distribution of
curvatures in the network. We show by various Internet data sets that the
distribution of Ricci cuvature is spread out, suggesting the network topology
to be non-homogenous. We also show that the Ricci curvature has interesting
connections to both local measures such as node degree and clustering
coefficient, global measures such as betweenness centrality and network
connectivity, as well as auxilary attributes such as geographical distances.
These observations add to the richness of geometric structures in complex
network theory.Comment: 9 pages, 16 figures. To be appear on INFOCOM 201
Impact of edge-removal on the centrality betweenness of the best spreaders
The control of epidemic spreading is essential to avoid potential fatal
consequences and also, to lessen unforeseen socio-economic impact. The need for
effective control is exemplified during the severe acute respiratory syndrome
(SARS) in 2003, which has inflicted near to a thousand deaths as well as
bankruptcies of airlines and related businesses. In this article, we examine
the efficacy of control strategies on the propagation of infectious diseases
based on removing connections within real world airline network with the
associated economic and social costs taken into account through defining
appropriate quantitative measures. We uncover the surprising results that
removing less busy connections can be far more effective in hindering the
spread of the disease than removing the more popular connections. Since
disconnecting the less popular routes tend to incur less socio-economic cost,
our finding suggests the possibility of trading minimal reduction in
connectivity of an important hub with efficiencies in epidemic control. In
particular, we demonstrate the performance of various local epidemic control
strategies, and show how our approach can predict their cost effectiveness
through the spreading control characteristics.Comment: 11 pages, 4 figure
Multiple Random Walks to Uncover Short Paths in Power Law Networks
Consider the following routing problem in the context of a large scale
network , with particular interest paid to power law networks, although our
results do not assume a particular degree distribution. A small number of nodes
want to exchange messages and are looking for short paths on . These nodes
do not have access to the topology of but are allowed to crawl the network
within a limited budget. Only crawlers whose sample paths cross are allowed to
exchange topological information. In this work we study the use of random walks
(RWs) to crawl . We show that the ability of RWs to find short paths bears
no relation to the paths that they take. Instead, it relies on two properties
of RWs on power law networks: 1) RW's ability observe a sizable fraction of the
network edges; and 2) an almost certainty that two distinct RW sample paths
cross after a small percentage of the nodes have been visited. We show
promising simulation results on several real world networks
The Directed Dominating Set Problem: Generalized Leaf Removal and Belief Propagation
A minimum dominating set for a digraph (directed graph) is a smallest set of
vertices such that each vertex either belongs to this set or has at least one
parent vertex in this set. We solve this hard combinatorial optimization
problem approximately by a local algorithm of generalized leaf removal and by a
message-passing algorithm of belief propagation. These algorithms can construct
near-optimal dominating sets or even exact minimum dominating sets for random
digraphs and also for real-world digraph instances. We further develop a core
percolation theory and a replica-symmetric spin glass theory for this problem.
Our algorithmic and theoretical results may facilitate applications of
dominating sets to various network problems involving directed interactions.Comment: 11 pages, 3 figures in EPS forma
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