Internet exchange point

Internet exchange points (IXes or IXPs) are common grounds of IP networking, allowing participant Internet service providers (ISPs) to exchange data destined for their respective networks. IXPs are generally located at places with preexisting connections to multiple distinct networks, i.e., datacenters, and operate physical infrastructure (switches) to connect their participants. Organizationally, most IXPs are each independent not-for-profit associations of their constituent participating networks (that is, the set of ISPs which participate at that IXP). The primary alternative to IXPs is private peering, where ISPs directly connect their networks to each other. IXPs reduce the portion of an ISP's traffic that must be delivered via their upstream transit providers, thereby reducing the average per-bit delivery cost of their service. Furthermore, the increased number of paths available through the IXP improves routing efficiency (by allowing routers to select shorter paths) and fault-tolerance. IXPs exhibit the characteristics of the network effect. Internet exchange points began as Network Access Points or NAPs, a key component of Al Gore's National Information Infrastructure (NII) plan, which defined the transition from the US Government-paid-for NSFNET era (when Internet access was government sponsored and commercial traffic was prohibited) to the commercial Internet of today. The four Network Access Points (NAPs) were defined as transitional data communications facilities at which Network Service Providers (NSPs) would exchange traffic, in replacement of the publicly financed NSFNET Internet backbone. The National Science Foundation let contracts supporting the four NAPs, one to MFS Datanet for the preexisting MAE-East in Washington, D.C., and three others to Sprint, Ameritech, and Pacific Bell, for new facilities of various designs and technologies, in New York (actually Pennsauken, New Jersey), Chicago, and California, respectively.