What Is Internet Exchange Point? A Beginner’s Guide to IXP

An internet exchange point (IXP) is a physical location somewhere around the world where internet traffic is exchanged between two or more internet networks. 

These are typically data centers where internet infrastructure companies, like content delivery networks (CDNs) and internet service providers (ISPs), connect with each other to exchange traffic. 

The use of internet exchange points benefit users as well as network operators. By connecting different internet networks directly through an exchange point, it is possible to route traffic more directly. While decreasing latency, potentially reducing costs and improving the speed and user experience. 

This article introduces how an internet exchange point works. What kind of connections help exchange traffic within them. And why they’re so useful to the efficient running of the internet. 

How does IXP work?

The internet is not one network but rather a collection of large, interconnected networks called autonomous systems (AS). These autonomous systems represent a collection of IP address prefixes controlled by the same organization. 

Network access points at IXPs are at the edge of each network. That’s because they’re where one network ends and another begins. They require an external gateway protocol to exchange traffic between the networks. 

Therefore, traffic that needs to be routed to an IP address outside an autonomous system network must be transmitted to different networks via the Border Gateway Protocol (BGP).

IXPs work by providing physical locations for each network to connect to others. The basic design of IXPs is not dissimilar to smaller networks like home Wi-Fi networks. In fact, an IXP is a type of local area network. The main difference is the size of the networks.  

These physical buildings stuffed with up to tens of thousands of ethernet switches interconnected with each other exchange traffic at a rate of between a few hundred Megabits per second to many Terabits per second, depending on the size and usage of the IXP. 

Without the IXPs’ help, each network would need to send data via intermediary transit networks. 

That said, transit providers are still useful. With the help of transit networks, every internet network doesn’t need direct connections to all internet service providers. Of course, relying solely on transit providers for all web traffic would lead to data traveling unnecessarily long distances to reach its destination. 

Say you were accessing a server in the same city. Unfortunately, there’s no guarantee that the data would travel to you without crossing half a continent without a local IXP. Essentially, an IXP contains local traffic locally. If it didn’t, you’d have to wait longer for a website to load. 

The Internet Exchange Map

Do you want to see a visual demonstration of where all of the world’s internet exchange points are located? Then use the Internet Exchange Map – a free and publically available resource. 

The Internet Exchange Map gives you a realistic impression of how the internet’s physical infrastructure maps across the planet. TeleGeography regularly updates and maintains this map.

IXP connection types

Network providers share data between networks using different methods. Depending on the destination, the type of networks exchanging data and whether they have a shared presence inside an IXP location. 

Most of the time, network operators use one of two types of connections to route traffic to and from other participating networks. It’s either peering within internet exchanges or transit connections if not using an IXP. Let’s review these types of connections deeper.

Peering

When two or more networks connect to exchange data within an internet exchange point, the process is referred to as peering. 

Peering is important since it drives down the cost of exchanging traffic for the member networks. Simultaneously, it increases the speed of data exchange. 

If networks operated without peering within internet exchange points, transmitting data from network A to network B would require a transmit provider. Not only does this represent higher costs for the exchange of data, but it typically also has a negative impact on the speed of data transfer. 

On the other hand, when two or more networks enter into a peering relationship, traffic can flow between them without the need for a transit provider. 

In most cases, when peering occurs between two larger networks, the arrangement is that neither party charges the other for transmitting data. This is settlement-free peering. However, in cases where a single network is significantly larger than another, it may charge for peering. This is why large networks tend to peer only with other large networks.

Other related costs include the shared upkeep of the infrastructure of the IXP where the peering is facilitated. 

Depeering

If a network decides that the peering arrangement they’ve agreed upon with other networks no longer suits them, they can go through the process of depeering. This is the process of reversing the peering arrangement. Depeering may occur if one party feels that the other party benefits more from the arrangement. Or when one party prefers to charge for traffic exchange. 

The end of a peering relationship often results in one network attempting to disrupt the traffic of another network with which it has a disagreement. 

Transit

In the discussion on peering, you were introduced to the idea of transit and transit providers. This is another type of connection that operates differently from the peer system. It also operates without the resources a single IXP provides. 

Instead of each network connecting to all networks as a peer, the transmit method of exchanging traffic involves a transmit provider delivering traffic through transit networks. 

Unlike an agreement between several different members, transit agreements tend to be between customers and their upstream providers. Therefore, IP transit services are paid services that allow an ISP to offer connectivity to the internet via multiple transit networks, using an IP address to navigate. 

In this scenario, the internet service providers are not paying a share of the infrastructure costs, like with peering. Instead, they pay the transit provider to route their traffic. 

Because traffic pathways tend to be more unpredictable and less direct, this is the slower type of connection. This, paired with its increased expense, means that most large ISPs tend to avoid transit services. 

Conclusion

Let’s quickly recap what we’ve covered so far. An internet exchange point (IXP) is an integral part of the global internet. It offers a physical location where internet infrastructure companies can exchange data across different networks. 

An internet exchange point is usually a data center where ISPs and CDNs connect and exchange internet traffic. Participating networks can route the traffic far more efficiently with the presence of an IXP. They can improve the time it takes to retrieve data, reduce latency and cut down on routing costs. 

Within these data centers full of network switches, the large networks of member companies exchange traffic via the Border Gateway Protocol. 

There are two main types of connections associated with IXPs. Peering and transit. Both exchange traffic and offer internet access in different ways. 

Peering involves two or more networks freely exchanging internet traffic back and forth without additional parties and usually without payment. Transit, on the other hand, relies on the paid services of a transit service to route traffic through multiple transit networks.