Connectivity in the commercial Internet

We study the 'backbone market' in the Internet. After discussing the struct ure of the Internet, we use an extension of the Katz-Shapiro network model to analyze the strategies that would be used by dominant backbone. We show that a larger backbone prefers a lower quality interconnection than the sma ller one. We then analyze a 'targeted degradation' strategy where the large r backbone lowers the quality of interconnection to its smaller rivals in t urn. Finally, we show that the qualitative results are robust to the possib ility of multihoming' by clients.