Figure 9
From: Router-level community structure of the Internet Autonomous Systems
The AS 17506 (Ucom Corporation, Japan). The structure of this Japanese AS with 4,739 nodes is organized into different clusters. Many of these clusters have a redundancy structure formed by 4 routers, which is a typical configuration in many ASes. Though the clusters can be clearly distinguished, they also constitute one large community which the Multiresolution Deltacom algorithm retrieves with a recall score of \(R_{2}=0.78\). Some nodes play a special role into this cohesion by acting as hubs. We can identify them by computing the eigenvector centrality, which is shown as the colour of the nodes in a light blue/blue/violet/red scale: the red nodes have the highest centrality values, and they are the main hubs. The classical modularity optimization throws a recall of 0.19 instead, because the AS is already combined with others at \(t=1\). On the other hand, Infomap obtains a recall of 0.13. (Image generated with Gephi.)