What Internet and Network Backbones Do

Illustration representing the world wide web spanning the globe
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In computer networking, a backbone is a central conduit designed to transfer network traffic at high speeds. Backbones connect local area networks (LANs) and wide area networks (WANs) together. Network backbones are designed to maximize the reliability and performance of large-scale, long-distance data communications. The best-known network backbones are those used on the Internet.

Internet Backbone Technology

Nearly all Web browsing, video streaming, and other common online traffic flows through Internet backbones.

They consist of network routers and switches connected mainly by fiber optic cables (although some Ethernet segments on lower traffic backbone links also exist). Each fiber link on the backbone normally provides 100 Gbps of network bandwidth. Computers rarely connect to a backbone directly. Instead, the networks of Internet service providers or large organizations connect to these backbones and computers access the backbone indirectly.

In 1986, the U.S. National Science Foundation (NSF) established the first backbone network for the Internet. The first NSFNET link only provided 56 Kbps - performance laughable by today's standards - although it was quickly upgraded to a 1.544 Mbps T1 line and to 45 Mbps T3 by 1991. Many academic institutions and research organizations used NSFNET, 

During the 1990s, the explosive growth of the Internet was largely funded by private companies who built their own backbones.

The Internet eventually became a network of smaller backbones operated by Internet Service Providers that tap into the biggest national and internal backbones owned by large telecommunications companies.

Backbones and Link Aggregation

One technique for managing the very high volumes of data traffic that flow through network backbones is called link aggregation or trunking.  Link aggregation involves the coordinated use of multiple physical ports on routers or switches for delivering a single stream of data.

For example, four standard 100 Gbps links that would ordinarily support different data streams can be aggregated together to provide one, 400 Gbps conduit. Network administrators configure the hardware on each of the ends of the connection to support this trunking.

Issues with Network Backbones

Due to their central role on the Internet and global communications, backbone installations are a prime target for malicious attacks. Providers tend to keep the locations and some technical details of their backbones secret for this reason. One university study on Internet backbone conduits in the U.S., for example, required four years of research and still is incomplete.

National governments sometimes maintain tight control over their country's outbound backbone connections and can either censor or completely shut off Internet access to its citizens.The interactions between large corporations and their agreements for sharing each other's networks also tend to complex business dynamics. The concept of net neutrality relies on the owners and maintainers of backbone networks to observe national and international laws and conduct business fairly.