The data speeds of backbone lines have changed with the times. The backbone is able to reroute traffic in case of a failure. The trunk line consists of many fiber optic cables bundled together to increase the capacity. It is typically a fiber optic trunk line. The Internet backbone is a conglomeration of multiple, redundant networks owned by numerous companies. 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 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. The Internet, and consequently its backbone networks, do not rely on central control or coordinating facilities, nor do they implement any global network policies. In the early days of the Internet, backbone providers exchanged their traffic at government-sponsored network access points (NAPs), until the government privatized the Internet, and transferred the NAPs to commercial providers. Within a few years, the dominance of the NSFNet backbone led to the decommissioning of the redundant ARPANET infrastructure in 1990. The combination of the ARPANET and NSFNET became known as the Internet. IBM, MCI and Merit upgraded the backbone to 45Mbit/s bandwidth (T3) in 1991. These sites included regional networks that in turn connected over 170 other networks. In 1987, this new network was upgraded to 1.5Mbit/s T1 links for thirteen sites. The National Science Foundation created NSFNET in 1986 by funding six networking sites using 56kbit/s interconnecting links and peering to the ARPANET. Other packet-switched computer networks began to proliferate in the 1970s, eventually adopting TCP/IP protocols or being replaced by newer networks. It used a backbone of routers called Interface Message Processors. The first packet-switched computer network was the ARPANET. Internet service providers, often Tier 1 networks, participate in Internet backbone traffic by privately negotiated interconnection agreements, primarily governed by the principle of settlement-free peering.

These data routes are hosted by commercial, government, academic and other high-capacity network centers, the Internet exchange points and network access points, that exchange Internet traffic between the countries, continents and across the oceans. The Internet backbone may be defined by the principal data routes between large, strategically interconnected computer networks and core routers on the Internet.

Internet trunk