Unraveling the impacts of IXP in internet ecosystem using bi-layered network

The Internet is a huge complex network, consisting of tens thousands of Autonomous Systems (ASes). Being a logical fabric of the Internet, the AS-level topology serves as a manageable and useful vehicle for the study of Internet characteristics. However, Internet exchange points (IXPs) have been ignored in previous studies despite of being one of the primary mechanisms for AS interconnections and playing an important role for improving data traffic. In this paper, a novel bi-layered network model is proposed to present an IXP-AS topology. The bi-layered network is built based on the actual architecture, from which a comprehensive study of current AS ecosystem and the impacts of IXP can be made. As revealed by network metrics applied onto the bi-layered network, IXP is always of higher centrality as compared with ASes, well matching its role. By comparing the results in 2009 and 2014, rapid growth in IXP number, membership and impacts are noticed. There are over 98% source-destination pairs routes (with shortest path routing protocol) affected by IXP in 2014. Our results also show that, being an IXP member is more favorable than being a non-member, hence it attracts many ASes, especially those with low centrality, in recent years.