May 12, 2022 | 5 min read
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How does peering work?

Salim Khouri

Director of Global Solutions Engineering

As IT practitioners contemplate network transformation from traditional networking strategies to lower cost direct internet access strategies, so comes a forest of acronyms and complexity: POPs, IXPs, ASNs, BGPs.

One of those subjects is peering. At Expereo, we take part in those strategic discussions every day. This is why, with the need for additional bandwidth and connectivity demands rising around the world, it’s important to be aligned with a strategic partner in the global internet market.

But what is peering, and how does it impact your network transformation strategy?

In this article, you’ll discover what peering actually does—and why it’s so important. In many ways, effective peering is the key to success with many of today's network strategies.

Let’s look at the basics of peering, in language you don’t need to be a computer expert to follow.

Peering into the past: the early internet

It seems strange now, but in the early days of the internet, the word “business” wasn’t even in the frame. The Internet started in the 1960s as a way for government researchers to share information. Computers in the '60s were large and immobile, and in order to make use of information stored in any one computer, one had to either travel to the site of the computer or have magnetic tapes sent through the conventional postal system.

Another catalyst in the formation of the Internet was the Cold War. The Soviet Union's launch of the Sputnik satellite spurred the U.S. Defense Department to consider ways information could still be disseminated even with damaged infrastructure. This led to ARPANET (Advanced Research Projects Agency Network), the network that ultimately evolved into what we now know as the Internet.

ARPANET was a great success, but membership was limited to certain academic and research organizations who had contracts with the Defense Department. In response to this, other networks were created to provide information sharing. And these various computer networks did not have a standard way to communicate with each other. So, a new communications protocol was established called Transfer Control Protocol/Internetwork Protocol (TCP/IP).

TCP/IP allowed different kinds of computers on different networks to "talk" to each other. ARPANET and the Defense Data Network officially changed to the TCP/IP standard on January 1, 1983, a date recognized as the birth of the Internet.

The world connects, thanks to peering

All networks could now be connected by a universal language. While the end systems they used were often incompatible (the first operating system had only just been invented), these agreements worked because those pioneers agreed to exchange data in a standard format and carry each other’s traffic between them. This was the first example of what we call “peering”: sharing the responsibility of carrying network traffic for the common good.

(The word itself stems from the sense of community those computer scientists felt: you peered because they were your social peers, and you felt peer pressure to do so.

The use of Peering grew quick in pioneering compute community. But by the end of 1973, that network was already international, with Norway and the UK connected by satellite. Ten years later, the DNS (Domain Name System) turned the anonymity of “dotted quad” addresses (like into readable names like

The modern internet: peering at scale

Today, tens of thousands of “little networks” (many of them far from small!) interconnect as our internet—so peering can’t be a nod between friends anymore. Because those networks aren’t run by individual technicians on first-name terms; they’re national telcos, global enterprises, entire countries. Accepting each other’s data traffic and sending it on its way isn’t a small task; it costs serious money and resources.

Surprisingly, perhaps the biggest factor is cultural. Many countries simply don’t have a tradition of peering and it's you-scratch-my-back-and-I’ll-scratch-yours way of thinking. Which is affecting the smooth flow of network traffic in multiple ways.

In China—to take one example—the three major carriers take a somewhat nuanced view of the co-operation needed for full peering, leading to wide variability across the vast country. Meaning connectivity can be great within a single city (covered by one telco) but poor between them (covered by a competing provider). And in South America—Brazil being a good example—network traffic is asymmetric, so peering represents a bad deal for one side. (Everyone’s streaming gigabytes of telenovela episodes, fewer are serving apps to offices.)

Solving these issues—and providing consistent, high-quality connectivity to our clients—needs attention to the deepest, most fundamental technologies of the internet.

Principles of peering

Some terminology first. Each “little network” (or collection of them) is called an Autonomous System, and has a Number (ASN) that identifies it to others. The “nodes” on each network (such as a website or web server in a datacenter) is further identified by an internet address.

This is how your data reaches its destination: homing in on the identifying numbers until it gets to the right place.

If there are only a few little networks (as in the early days) interconnecting is simple—just run wires between them. But with more networks it gets complicated. So, for many years, Autonomous Systems have “joined up” at Internet Exchange Points, or IXPs, and interconnected on the same set of wires. This is called “public peering”, since everybody shares the same infrastructure.

Public peering works. But for large networks, there’s a problem: sharing the connections with everyone else means they might run into congestion. (Just like a public highway at rush hour). So Expereo solves this with private peering: building its own road for customer data to travel on.

This “private road” can take several forms—from a simple cable connecting two server racks to a high-capacity circuit connecting two countries. But it has two common features: it’s located at an Expereo POP (Point of Presence) where public data traffic is “handed off” into Expereo’s control, and it can handle BGP (Border Gateway Protocol), a system that tells that traffic where to go next.

Peering with partners

This means once data arrives at an Expereo POP, it has the added benefit of Expereo’s vast peering network— we have thousands of optimized routes in place worldwide. This is vital, for a reason that goes all the way back to 1973: it’s a two-way agreement, with both sides sharing the load for a common goal. And when you have lots of peering partners, it’s easier to keep those relationships balanced.

Second benefit is control over BGP and the “routing tables” that govern how data traffic hops, skips, and jumps across the internet. Expereo Cloud Acceleration routes your data dynamically and intelligently, always picking the best and fastest paths—resulting in higher QOS. And with new SD-WAN Gateways, designed specifically to keep your global Wide Area Networks flowing smoothly, the improvements are greater still.

That’s how peering works for Expereo—and therefore for you, our customers. Looking intelligently at where networks interconnect, the supply and demand of bandwidth between them, and arranging agreements that let us offer high-quality SLAs and other guarantees.


Peering these days may be all about business. But there’s still an echo of those early days when Vint talked to Bob about how they’d connect two PDP-10s. Because it’s still about building effective partnerships. And—as our enterprise customers in over 190 countries agree—partnerships are one thing Expereo is very, very good at. 

Salim Khouri

Director of Global Solutions Engineering

With over 20 years’ experience as a technology professional, Salim is the Director of Solutions Engineering to support Expereo’s managed global network and cloud connectivity solutions. His expertise includes, but is not limited to Global Internet, SD-WAN, and Security.

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