The infrastructure of the Internet can be considered as the cyber equivalent of an ecosystem. At its heart is a mesh of interconnected backbone networks. This core is rapidly evolving and provides the underpinnings that will be vital for future national and international communications.

The last mile connections from the Internet to homes and businesses are supplied by thousands of small and medium sized Internet Service Providers (ISPs), which are in turn interconnected by 'arteries' maintained by transit (backbone) providers. The global infrastructure of the Internet consists of a complex array of telecommunications carriers and providers, a very difficult infrastructure to analyze diagnostically except within the borders of any individual network. Nonetheless it is critical for the evolution of the Internet that insights into its overall health and scalability are obtained.

This paper is a copy of the one found at http://www.nature.com/nature/webmatters/tomog/tomog.html.