What is a Backbone Connection?
The Internet backbone
refers to the principal data routes between large, strategically interconnected networks and core routers in the Internet. These data routes are hosted by commercial, government, academic and other high-capacity network centers, the Internet exchange points and network access points, that interchange Internet traffic between the countries, continents and across the oceans of the world. Internet service providers (often Tier 1 networks) participate in Internet backbone exchange traffic by privately negotiated interconnection agreements, primarily governed by the principle of settlement-free peering.
The first high speed backbone was created by the National Science Foundation in 1987. It was called the NSFNET, and was a T1 line that connected 170 smaller networks together. The following year, IBM, MCI and Merit would create a T3 backbone. In the early days of the Internet, backbone providers exchanged their traffic at government-sponsored network access points, until the government privatized the Internet, and then transferred the NAPs to commercial providers.
The Internet, and consequently its backbone networks, do not rely on central control or coordinating facilities, nor do they implement any global network policies. The resilience of the Internet results from its principal architectural features, most notably the idea of placing as few network state and control functions as possible in the network elements, but instead relying on the endpoints of communication to handle most of the processing to ensure data integrity, reliability, and authentication. In addition, the high degree of redundancy of today's network links and sophisticated real-time routing protocols provide alternate paths of communications for load balancing and congestion avoidance.
The Internet backbone is a conglomeration of multiple, redundant networks owned by numerous companies. It is typically a fiber optic trunk line. The trunk line consists of many fiber optic cables bundled together to increase the capacity. The backbone is able to reroute traffic in case of a failure. The data speeds of backbone lines have changed with the times. In 1998, all of the United States backbone networks had utilized the slowest data rate of 45 Mbit/s. However the changing technologies allowed for 41 percent of backbones to have data rates of 2,488 Mbit/s or faster by the mid 2000's. Fiber-optic cables are the medium of choice for Internet backbone providers for many reasons. Fiber-optics allow for fast data speeds and large bandwidth; they suffer relatively little attenuation, allowing them to cover long distances with few repeaters; they are also immune to crosstalk and other forms of EM interference which plague electrical transmission.
Because of the enormous overlap between long distance telephone networks and the Internet backbone networks, the largest long distance voice carriers such as AT&T, MCI, Sprint and CenturyLink also own some of the largest Internet backbone networks. These backbone providers will then sell their services to ISPs. Each ISP has its own contingency backbone network, and at the very least, is equipped with an outsourced backup. These networks are intertwined and crisscrossed to create a redundant network. Many companies operate their own backbones, that are all interconnected at various IXPs around the world. In order for data to navigate through this diverse web that the backbone creates, backbone routers are needed. These backbone routers are routers that are powerful enough to handle information on the Internet backbone, and they direct data to other routers in order to send it to its final destination. Without these backbone routers, information would be lost since data would not know how to locate its end destination. The very largest providers, known as Tier 1 providers, have such comprehensive networks that they never need to purchase transit agreements from other providers. As of 2000 there were only five Internet backbone providers at the Tier 1 level in the telecommunications industry. These carriers included Cable & Wireless Worldwide, UUNet, Sprint, AT&T and Genuity. As of 2010 however, Verizon has become "the world's most connected Internet backbone." Verizon has a very large Internet footprint that reaches all over the world due to their diverse customer base which includes small and medium size businesses, large corporations, content providers, and many more. They have held this top spot for 11 of the past 12 years. Verizon also plans to increase backbone speeds in the U.S to 100 Gbit/s, the first company to do so. Some of this enhanced data speed can be seen on routes from Chicago to New York and Minneapolis to Kansas City.
Economy of the backbone
Backbone providers of roughly equivalent market share regularly create agreements called peering agreements. These agreements allow the use of another's network to hand off traffic where it is ultimately delivered. They usually do not charge each other for this use as they all get revenue from their customers regardless.
Backbone providers of unequal market share usually create agreements called transit agreements, and usually contain some type of monetary agreement.
Antitrust authorities have acted to ensure that no provider grows large enough to dominate the backbone market. The FCC has also decided not to monitor the competitive aspects of the Internet Backbone interconnection relationships, as long as the market continues to function well without regulation.