in accordance with the terminology of the National Information Infrastructure document. All four are now defunct or no longer functioning as Internet exchange points: MAE-East – Located in Tysons Corner, Virginia, and later relocated to Ashburn, Virginia Chicago NAP – Operated by Ameritech and located in Chicago, Illinois New York NAP – Operated by Sprint and located in Pennsauken, New Jersey San Francisco NAP – Operated by PacBell and located in the Bay Area As the Internet grew, and traffic levels increased, these NAPs became a network bottleneck. Most of the early NAPs utilized FDDI technology, which provided only 100 Mbit/s of capacity to each participant. Some of these exchanges upgraded to ATM technology, which provided OC-3 (155 Mbit/s) and OC-12 (622 Mbit/s) of capacity. Other prospective exchange point operators moved directly into offering Ethernet technology, such as gigabit Ethernet (1,000 Mbit/s), which quickly became the predominant choice for Internet exchange points due to the reduced cost and increased capacity offered. Today, almost all significant exchange points operate solely over Ethernet, and most of the largest exchange points offer 10, 40, and even 100 gigabit service. During the dot-com boom, many exchange point and carrier-neutral colocation providers had plans to build as many as 50 locations to promote carrier interconnection in the United States alone. Essentially all of these plans were abandoned following the dot-com bust, and today it is considered both economically and technically infeasible to support this level of interconnection among even the largest of networks. How peering works The Internet is a collection of separate and distinct networks referred to as autonomous systems, each one consisting of a set of globally unique IP addresses and a unique global BGP routing policy. The interconnection relationships between Autonomous Systems are of exactly two types: Peering - Two networks exchange traffic between their users freely, and for mutual benefit. Transit – One network pays another network for access to the Internet. Therefore, in order for a network to reach any specific other network on the Internet, it must either: Sell transit service to that network or a chain of resellers ending at that network (making them a 'customer'), Peer with that network or with a network which sells transit service to that network, or Buy transit service from any other network (which is then responsible for providing interconnection to the rest of the Internet). The Internet is based on the