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Internet Backbone Technology

(Internet Connectivity Distribution - Wikipedia)

- Network Backbones

The data is first broken into small packets of information, as it cannot be sent whole. The data then travels through a physical route to its destination, commonly consisting of a possible mix of  co-axial cables, a twisted-pair cable, or fibre optics. This physical route of cables is called the transmission medium. Each transmission medium is restricted to a fixed capacity known as the the bandwidth. In order to successfully transmit data, a minimum bandwidth is required which depends on the data being transported. Data being transported at 300 Mb/s, for instance, requires a minimum of 1 gigabit of ethernet transport. 

The Internet generates massive amounts of computer-to-computer traffic, and insuring all that traffic can be delivered anywhere in the world requires the aggregation of a vast array of high-speed networks collectively known as theIinternet backbone. 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. The Internet backbone is made up of many large networks which interconnect with each other. 


- The Internet Backbone

The Internet backbone may be defined by the principal data routes between large, strategically interconnected computer 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 exchange Internet traffic between the countries, continents and across the oceans. 

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. 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.

Internet service providers participate in Internet backbone traffic by privately negotiated interconnection agreements, primarily governed by the principle of settlement-free peering. The interactions between large corporations and their agreements for sharing each other's networks also tend to complex business dynamics. 

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. Although the Internet is publicly accessible, it is woven together from many privately owned networks that interoperate. Telecommunications companies sometimes show schematics of their core networks, but without much geographic detail. Knowing the exact location of the most important Internet cables should help efforts to understand the possible effects of natural disasters or intentional attacks on the Internet.


(Photo: Princeton University, Office of Communications)

- Modern Internet Backbone: No One Owns The Internet All

No government can lay claim to owning the Internet, nor can any company. The Internet is more of a concept than an actual tangible entity, and it relies on a physical infrastructure that connects networks to other networks. The Internet is like the telephone system - no one owns the whole thing. 

Today, several large corporations provide the routers and cable that make up the Internet backbone. These companies are upstream Internet Service Providers (ISPs).  There are many organizations, corporations, governments, schools, private citizens and service providers that all own pieces of the infrastructure. There are, however, organizations that oversee and standardize what happens on the Internet and assign IP addresses and domain names, such as National Science Foundation, the Internet Engineering Task Force, ICANN, InterNIC and the Internet Architecture Board. 

Because of the enormous overlap between long-distance telephone networks and backbone networks, the largest long-distance voice carriers such as AT&T, Verizon, 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 which 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.


- Tier 1 Internet Service Providers (ISPs)

Like any other network, the Internet consists of access links that move traffic to high-bandwidth routers that move traffic from its source over the best available path toward its destination. This core is made up of individual high-speed fiber-optic networks that peer with each other to create the internet backbone. The individual core networks are privately owned by Tier 1 ISPs, giant carriers whose networks are tied together. These providers include AT&T, CenturyLink, Cogent Communications, Deutsche Telekom, Global Telecom and Technology (GTT), NTT Communications, Sprint, Tata Communications, Telecom Italia Sparkle, Telia Carrier, and Verizon. 

Today, these large corporations provide the routers and cable that make up the Internet backbone. These companies are upstream ISPs. By joining these long-haul networks together, Tier 1 ISPs create a single worldwide network that gives all of them access to the entire Internet routing table so they can efficiently deliver traffic to its destination through a hierarchy of progressively more local ISPs. Please refer to Wikipedia: The Internet Connectivity Distribution for more details.


- Internet Exchange Points (IXPs)

Internet exchange points (IXP) tie the backbone together. Backbone (Tier 1) ISPs connect their networks at peering points, neutrally owned locations with high-speed switches and routers that move traffic among the peers. These are often owned by third parties, sometimes non-profits, that facilitate unifying the backbone. Participating Tier 1 ISPs help fund the IXPs, but don’t charge each other for transporting traffic from the other Tier 1 ISPs in a relationship known as settlement-free peering. Such agreements eliminate potential financial disputes that might have the result of slowing down Internet performance.

The Internet backbone is made up of the fastest routers, which can deliver 100 Gbps trunk speeds. These routers are made by vendors including Cisco, Extreme, Huawei, Juniper, and Nokia, and use the border gateway protocol (BGP) to route traffic among themselves.


- Tier 2 and Tier 3 ISPs

Below the Tier 1 ISPs are smaller Tier 2 and Tier 3 ISPs. Tier 3 providers provide businesses and consumers with access to the Internet. These providers have no access of their own to the Internet backbone, so on their own would not be able to connect their customers to all of the billions of Internet-attached computers. Buying access to Tier 1 providers is expensive. So often Tier 3 ISPs contract with Tier 2 (regional) ISPs that have their own networks that can deliver traffic to a limited geographic area but not to all Internet-attached devices. In order to do that, Tier 2 ISPs contract with Tier 1 ISPs for access to the global backbone, and in that way make the entire internet accesssible to their customers. 

This arrangment makes it possible for traffic from a computer on one side of the world to connect to one on the other side. That traffic goes from a source computer to a Tier 3 ISP that routes it to a Tier 2 ISP that routes it to a Tier 1 backbone provider that routes it to the appropriate Tier 2 ISP that routes it to a Tier 3 access provider that delivers it to the destination computer.


- Internet Connectivity Distribution

A Tier 1 network is an Internet Protocol (IP) network that can reach every other network on the Internet solely via settlement-free interconnection (also known as settlement-free peering). Tier 1 networks can exchange traffic with other Tier 1 networks without having to pay any fees for the exchange of traffic in either direction, while some Tier 2 networks and all Tier 3 networks must pay to transmit traffic on other networks.




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