The Two Highways of the Internet
Imagine the internet as a global system of highways. In this analogy, there are two main ways for data to travel. First, there’s “transit.” This is like paying a national shipping company to deliver a package anywhere in the country. A smaller network
pays a larger network, or transit provider, a fee for access to the entire global internet. The transit provider has connections everywhere and guarantees your data will get to its destination, no matter how obscure. It’s a simple, paid service: you pay them to handle the complexity of global delivery. Then there’s “peering.” This is more like two neighboring towns of roughly the same size agreeing to build a direct road between them so their residents can visit each other for free. In the internet world, two networks of a similar scale (like major ISPs) agree to exchange traffic between their respective customers directly, without charging each other. This is often called “settlement-free” peering because no money changes hands. It’s a mutually beneficial handshake deal to save costs and improve performance for their own users.
A Trip Back to the 90s Internet
To understand why this dual system exists, we have to go back to the mid-1990s. Before then, the internet’s backbone was a government-funded academic and research project called NSFNET. Commercial traffic was largely forbidden. But as the internet’s potential became obvious, the National Science Foundation (NSF) planned to privatize it.
In 1995, the NSFNET was decommissioned, and the internet was handed over to the private sector. To ensure the newly fragmented commercial internet could still function as a unified network, the NSF funded the creation of a few key locations called Network Access Points (NAPs). These NAPs were physical locations where the newly competing commercial network providers—like Sprint, Ameritech, and Pacific Bell—could connect their routers and exchange traffic. This was the moment the modern commercial internet was born, and it immediately created a fundamental business problem: who should pay whom?
The Real Reason: Economics and Power
This is where the design choice becomes clear. The “real reason” for the peering vs. transit split wasn’t technical; it was driven by economics and a desire for competitive advantage. The massive new networks—the Tier 1 providers who had just taken over the internet’s backbone—looked at each other and realized they were all equals. They each had vast infrastructure and a similar number of customers. So why would they pay each other to exchange traffic when the flow of data between them was more or less balanced?
They decided they wouldn’t. They agreed to peer with each other for free, creating an exclusive club at the top. This allowed them to save enormous amounts of money they would have otherwise spent paying for transit. But for any smaller, up-and-coming network, the deal was different. The big players had no incentive to offer them a free ride. Instead, they told the smaller networks: “If you want to reach our customers, and by extension the rest of the internet, you have to pay us.” That paid service is transit. This created a hierarchical system where large, established players exchanged traffic for free among themselves while monetizing access for everyone else.
Why This Still Shapes Your Internet Today
This foundational structure from the 90s still dictates how the internet works. Peering reduces costs and latency, which is why major content companies like Netflix and Google heavily invest in direct peering relationships with ISPs—it gives them a faster, more direct path to get their content to you. When those peering relationships break down or become strained, as they have in famous disputes, users can experience buffering and slower speeds.
The transit and peering system also influences network reliability and redundancy. Most networks use a blend of both; they peer where it’s cost-effective and buy transit to ensure they can reach every corner of the internet they can't access via a peering agreement. So, the next time you stream a movie or visit a website, remember that the speed and quality of your connection are direct results of these decades-old business arrangements, a hidden battle of cost and control that determines how data flows across the globe.
