In our last blog, we talked about internet speed tests, and the many factors that can influence them. One of those factors which we did not discuss is called a “content delivery network.”
A Content Delivery Network, or CDN, is a term for a particular way of distributing internet content. Traditionally, when you browse to a website from your computer, the information is pulled from the website, carried over the internet, sent through an unknown amount of Internet Exchange Points to your local network, and then translated by your browsing software.
In a CDN, content providers (e.g. Netflix) place servers with the most accessed content in strategically placed locations at the very edge of where the Internet meets your local network (often in the central office of your ISP).
The benefit of a CDN structure for the end user is that the information is able to be delivered much more quickly and efficiently. The closer to the edge the content resides, the less devices it has to pass through, and the less likely it is to encounter some form of resistance or traffic.
Internet traffic is very similar to actual traffic in that the amount of it that is sustainable is dependent on how wide the road is and how many other people are traveling on it at the same time. If a typical internet connection is like driving a car down the information superhighway, a CDN is more like flying to an airport close to your destination, and then renting a car to drive the last 20 miles.
The benefit of a CDN structure for the ISP includes increased reliability, reduced costs, and improved security. Most ISPs purchase bandwidth from one of the Tier 1 internet providers, so by decreasing their need to download information from the internet-at-large, they can reduce costs.
CDN servers, by storing the content users are accessing most often in a local server, is one of the easiest ways to decrease that need. They also make it possible to download content even when that content provider’s website might be down. Finally, since less information is being transmitted from the Internet, there is less of a security risk since all routing is done locally.
CDN servers are usually obtained by the ISP directly from the content provider. This business arrangement can take many forms. Typically, the server is provided at no cost, as the content provider wants the end user to have the best experience with their content possible. However, the FCC’s removal of net neutrality rules in 2017 opened the doors to the possibility of ISPs favoring some traffic over others, which could take the form of “pay to play” CDN situations. More on that in a future blog on the topic of net neutrality.