Lecture 15: Internet Topology and Structure

USA Internet Structure

The Internet in the USA has always used a backbone topology, with the National Science Foundation Network (NSFNET) providing the original backbone network.

In 1995, this structure was privatised, with a variety of commercial organisations (National Service Providers (NSPs) taking over the backbone functionality. Interconnections between these organisations occur at a number of Network Access Points (NAPs). NSPs are said to peer with other NSPs at the NAPs, with complex financial arrangments in place to "carry each other's packets".

NSPs provide ISP service to Regional Internet Service Providers, with the possibility of private peering between R-ISPs. Retail, or local, ISPs generally connect to a Regional ISP and offer dial-in (and possibly permanent) services to the public. Note that the distinction between each of these classes of provider can become rather blurred, especially in Australia!

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