The Internet backbone refers to the principal data routes between large, strategically interconnected networks and core routers on 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, and 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.
||The examples and perspective in this section may not represent a worldwide view of the subject. (September 2011)|
Because of the enormous overlap between long-distance telephone networks and backbone networks, the largest long-distance voice carriers such as AT&T Inc., MCI, Sprint, and CenturyLink also own some of the largest Internet backbone networks. These backbone providers sell their services to Internet service providers (ISPs).
Each ISP has its own contingency network and 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 Internet exchange points (IXPs) around the world. In order for data to navigate this web, it is necessary to have backbone routers, which are routers powerful enough to handle information on the Internet backbone and are capable of directing data to other routers in order to send it to its final destination. Without them, information would be lost because data does not know how to locate its end destination.
Tier 1 providers
The 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 tier 1 providers in the telecommunications industry. Current Tier 1 carriers include CenturyLink, Cable & Wireless Worldwide, UUNet, Sprint, AT&T Corporation, and Genuity.
Economy of the backbone
Backbone providers of roughly equivalent market share regularly create agreements called peering agreements, which allow the use of another's network to hand off traffic where it is ultimately delivered. Usually they do not charge each other for this, as the companies get revenue from their customers regardless.
Antitrust authorities have acted to ensure that no provider grows large enough to dominate the backbone market. In the United States, the Federal Communications Commission has decided not to monitor the competitive aspects of the Internet backbone interconnection relationships as long as the market continues to function well.
The government of Egypt shut down the four major ISPs on January 27, 2011 at approximately 5:20 p.m. EST. Evidently the networks had not been physically interrupted, as the Internet transit traffic through Egypt, such as traffic flowing from Europe to Asia, was unaffected. Instead, the government shut down the border gateway protocol (BGP) sessions announcing local routes. BGP is responsible for routing traffic between ISPs.
Only one of Egypt's ISPs was allowed to continue operations. The ISP Noor Group provided connectivity only to Egypt's stock exchange as well as some government ministries. Other ISPs started to offer free dial-up Internet access in other countries.
Europe is a major contributor to the growth of the international backbone as well as a contributor to the growth of Internet bandwidth. As of 2003, Europe is credited with 82 percent of the world's international cross-border bandwidth. The company Level 3 Communications has begun to launch a line of dedicated Internet access and virtual private network services which gives large companies direct access to the tier 3 backbone. Connecting companies directly to the backbone will provide enterprises faster Internet service which meets a large market need.
Certain countries around Caucasus have very simple backbone networks; for example, in 2011, a woman in Georgia pierced a fiber backbone line with a shovel and left the neighboring country of Armenia without Internet access for 12 hours.
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With more than 100 million Internet users as of 2009, India's backbone is extremely extensive. Four of India's top Internet service providers are Tata Communications, BSNL, MTNL, and Reliance Communications. Tata Communications is a tier 1 IP network, with connectivity to more than 200 countries across 400 PoPs and nearly 1,000,000 square feet (93,000 m2) of data center and colocation space worldwide. It is India's largest provider in data center services and also operates India's largest data center in Pune. The backbone structure continues to grow due to the huge number of emerging mobile operators, which leads to decreasing prices thanks to market competition.
Japan's Internet backbone needs to be very efficient due to the high demand for the Internet and technology in general. Japan had over 86 million Internet users in 2009, and it is projected to climb to nearly 91 million Internet users by 2015. Since Japan has a demand for fiber to the home, Japan is looking into tapping a fiber-optic backbone line of Nippon Telegraph and Telephone (NTT), a domestic backbone carrier, in order to deliver this service at cheaper prices.
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