Francesco Sorrentino — Page 5

arXiv2005

Synchronization of degree correlated physical networks

We propose that negative degree correlation among nodes in a network of nonlinear oscillators, often detected in real world networks, is motivated by its positive effects on synchronizability. In so doing, we use a novel methodology to characterise degree correlation based on clustering the network vertices in p classes according to their degrees. Using this strategy we construct networks with an assigned power law distribution but changing degree correlation properties. We find that the network synchronizability improves when the network becomes dissassortative, i.e. when nodes with low degree are more likely to be connected to nodes with higher degree. Our numerical observations are confirmed by the analytical estimates found in this letter using an innovative approach based on the use of graph theoretical results.

cond-mat.dis-nn↗

arXiv2005

Effects of variations of load distribution on network performance

This paper is concerned with the characterization of the relationship between topology and traffic dynamics. We use a model of network generation that allows the transition from random to scale free networks. Specifically, we consider three different topological types of network: random, scale-free with γ= 3, scale-free with γ= 2. By using a novel LRD traffic generator, we observe best performance, in terms of transmission rates and delivered packets, in the case of random networks. We show that, even if scale-free networks are characterized by shorter characteristic-path- length (the lower the exponent, the lower the path-length), they show worst performances in terms of communication. We conjecture this could be explained in terms of changes in the load distribution, defined here as the number of shortest paths going through a given vertex. In fact, that distribu- tion is characterized by (i) a decreasing mean (ii) an increas- ing standard deviation, as the networks becomes scale-free (especially scale-free networks with low exponents). The use of a degree-independent server also discriminates against a scale-free structure. As a result, since the model is un- controlled, most packets will go through the same vertices, favoring the onset of congestion.

cs.NI↗