The performance and availability of CDNs

Content delivery networks (or CDNs) offer a reliable content distribution system for websites and applications. These systems work to speed up content delivery (webpages, video, games, downloadable objects, streamable media, and even software updates) to web users based on their geographical location and performance.

In recent times there’s been an unprecedented number of companies questioning the performance and availability of CDNs. This is following events where CDNs have impacted the availability of a large number of websites.

It was discovered that a root cause of these CDN issues was the fact that many of the companies who lost availability were using a single pure-play CDN (where you have a single provider using their own infrastructure). These are traditionally designed as hardware- or network-based, with PoPs deployed in geographical locations and shaped around the provider’s preference – which has often been based upon the most economical option and, therefore, not necessarily the best performing option. And although the single CDNs are marketed and perceived as providing speed, security and high availability, no single CDN provider could possibly offer the best performance everywhere in the world at every point in time.

In contrast to single CDNs, multi-CDN solutions are deployed as an overlay of individual CDNs, creating a combination of various PoPs from different CDN providers. This solution typically offers more PoPs spanning a much larger geographical area, and also gives optimal performance and virtually infinite scale, all across the globe.

Content providers and CDN
We’ve witnessed the uptake of multi-CDN solutions over the last few years amongst large content owners/providers, deploying these solutions to improve the end-user experience and delivery. Nowadays, this solution is getting as much traction with smaller content/providers owners, or in fact every CDN user.

There are different ways to run a multi-CDN switching platform, and the way to do it is dependent on the traffic type and use case. The most promising and interesting method uses an optimised strategy that leverages performance metrics in the decision-making process by deploying a multi-CDN platform. This means that the CDN chosen is the ‘best’ performing CDN, which has received the highest score across the board. In that case, the evaluation is based on new QoE metrics based on the specific region, for the specific piece of content, and considering the ISP and device of the end-user intending to access the content.

A multi-CDN should be considered as a solution to tackle the following critical aspects: service availability, scalability, and avoidance of a single point of failure. A major bonus is that this comes as one solution that is managed by one provider, and hence they remove the stress of managing multiple CDN providers at the same time.

With the uncontrollable spread of mobile and connected devices, media consumption is at its height and showing no signs of slowing down. Consumers expect flawless and real-time services, with no interruptions. We now live in a hyper-connected world with expectations of 100% uptime, at all times. This can only be achieved with a strong multi-CDN strategy.

Wilfried Dudink is managing director CDN at Leaseweb.