Last updated: June 9, 2020
Why a CDN makes many gaming sites possible
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The CDN is an optional extra to your regular hosting plan.
But for some businesses, the CDN is a core part of the service they offer.
Valve's Steam platform is a digital store and a content delivery system for PC and Mac games. Think of it as the 'iTunes of gaming'.
The files being downloaded over Steam are huge; 15-20 GB or more, in some cases. The system also stores game data, authenticates players and coordinates multiplayer matches.
Steam is inherently very vulnerable to downtime.
How Steam Uses it CDN
Valve has set up a massive CDN to keep Steam gamers online. It covers more than 55 locations and is served by hundreds of servers. It's so massive, it can handle more than half a terabyte of transfer per second.
The CDN is also cleverly designed.
Gamers are rarely than 1,000 miles from two Steams CDN locations. The network is totally redundant, and there's practically no difference in speed between the closest and the next closest location. For a gamer to notice a speed drop, at least two locations near them would have to fail. Even then, their game would still be available unless there is a massive catastrophic event that takes out more than half a dozen locations.
But it's not all good news for Steam gamers.
Giving Users Choice
As powerful as the Valve CDN is, it's not perfect.
Individual datacenters can become overloaded. That can cause download speeds to fall.
While a 30 kb/s download speed might be adequate for downloading an image or a web page, it makes a 10 GB game download impractical.
There is a way around this.
Users can choose the location they want to use. If their nearest location becomes overloaded, they just switch to a more distant one. This is one of the tools that makes the Steam network bearable at busy times.
While using locations far away isn't ideal, it's better than having no CDN at all.
Steam Needs its CDN
Steam would not be exist without CDNs.
If only one datacenter were to be used, it would be too slow. The content simply has to be distributed and synchronised for the idea to work.
As a case study, Steam is fascinating. It's the most efficient way of distributing data, and it has triggered a wave of new PC game development.
Though it may not be the absolute fastest way to acquire content, it's a convenient and affordable way to enjoy it.