The internet is made up of hundreds of thousands of connections, linked together through miles and miles of cables stretching all over the world and into millions of homes and businesses in every country. 

But not all connections are created equal, and some are much more important than others. At the core of all these connections is the internet backbone: the principal data routes between large, strategically interconnected computer networks and core routers of the Internet.

Internet backbones are the largest data connections on the Internet. These very high-speed data transmission lines provide networking facilities to relatively small but high-speed Internet service providers all around the world.

Primarily owned by commercial, educational, government and military entities, backbone networks facilitate a stable and secure foundation for internet service providers to provide internet access to end users and businesses.

How does the internet backbone work?

Positioned at the top of the Internet ecosystem are tier 1 networks. These networks maintain and operate their own internet backbone, and are sufficiently comprehensive that they don’t purchase IP transit from anyone else. 

Learn more about how the internet works in our article: Building an ISP’s connectivity – Points of Presence, Upstream Internet Providers & Internet Exchanges

Typically, networks lower down in the hierarchy pay for upstream IP transit, while networks of similar size and merit peer with each other. Tier 1 networks exchange their internet backbone through privately negotiated interconnection agreements with other large networks on the principle of settlement-free IP peering, while small networks take on transit agreements.

Transit agreements are a monetary contract between ISPs. These agreements set up a process to share traffic loads or to handle data traffic in case of a partial failure of some networks, providing improved capacity and stability for all providers on the network.

What makes for a strong internet backbone?

As tier 1 networks pass down access to their networks to ISP’s, the quality of any internet service provider is directly related to the performance of their upstream providers. In this way, understanding the upstream network of your provider is vital to securing a fast and reliable connection.

Alternatively, an ISP can license with multiple backbone networks to ensure optimal performance regardless of interruptions or issues with upstream providers. By utilising multiple networks, your ISP can ensure a strong internet backbone in 4 main areas:


How much of the network does the backbone cover. A larger reach generally means a service provider has greater control of network resources, and ultimately, quality of service. More reach also often includes more diverse connections, meaning you can connect to local, regional and international networks with minimal latency.


Not every internet backbone owns the infrastructure – it can be quite common for tier 1 networks to be built on leased capacity instead. While this might seem like a drawback, by utilising multiple leased lines, a backbone network can quickly scale up to meet increased demand, or to provide internet access to new areas.


Backbone networks need to connect with other large networks around the world in order to ensure high quality internet service downstream, and how close they are to these large networks determines how much impact they can have on that quality. Choosing a network with high proximity to other major networks will generally see higher performance.


Along with who the backbone network connects with, how they connect is also vital to their performance. Is your internet backbone part of a well-managed ecosystem of private peering connections with critical networks? How many connections are there between your backbone and where your data is?


Where is the physical presence of your network? Often referred to as points of presence, these are the physical locations of routers, switches, servers and any other necessary devices for traffic to cross over networks. Having multiple points of presence does not always mean a better connection, instead location is crucial.