MEDUSA - New Model of Internet Topology Using k-shell Decomposition

TL;DR

This paper introduces a new model called Medusa for the Internet's topology based on k-shell decomposition, revealing a core-periphery structure with a fractal interconnection pattern among Autonomous Systems.

Contribution

The paper applies k-shell decomposition to Internet AS data, unveiling a novel Medusa topology model with a large core and two distinct peripheral components.

Findings

Identified a large, redundantly connected core of nearly 100 ASes.

Discovered two components flowing data in and out from the core.

Proposed the Medusa model as a new framework for Internet topology analysis.

Abstract

The k-shell decomposition of a random graph provides a different and more insightful separation of the roles of the different nodes in such a graph than does the usual analysis in terms of node degrees. We develop this approach in order to analyze the Internet's structure at a coarse level, that of the "Autonomous Systems" or ASes, the subnetworks out of which the Internet is assembled. We employ new data from DIMES (see http://www.netdimes.org), a distributed agent-based mapping effort which at present has attracted over 3800 volunteers running more than 7300 DIMES clients in over 85 countries. We combine this data with the AS graph information available from the RouteViews project at Univ. Oregon, and have obtained an Internet map with far more detail than any previous effort. The data suggests a new picture of the AS-graph structure, which distinguishes a relatively large, redundantly connected core of nearly 100 ASes and two components that flow data in and out from this core. One component is fractally interconnected through peer links; the second makes direct connections to the core only. The model which results has superficial similarities with and important differences from the "Jellyfish" structure proposed by Tauro et al., so we call it a "Medusa." We plan to use this picture as a framework for measuring and extrapolating changes in the Internet's physical structure. Our k-shell analysis may also be relevant for estimating the function of nodes in the "scale-free" graphs extracted from other naturally-occurring processes.