CDNs fail in enterprise applications

The growth of Internet-based business and communications services has increased the need for speed, accuracy and availability in network-delivered content. While proxy servers have been useful in assisting rapid content delivery, content delivery networks (CDNs) have provided the missing link, providing overlay networks that offer high-performance delivery.

Due to the significant success of the CDN models that have been deployed by several companies worldwide, such as Akamai, Cloudflare, Limelight, Level 3 and many more, enterprise organisations are approaching them to assist in delivering their business-critical applications over the same network.

Unfortunately, in almost all cases, this does not work. To understand why they fail to deliver enterprise applications, companies need a better understanding of what CDNs have been successful at, as well as what their network design looks like.

The establishment of a CDN in any remote location of the world, like South Africa, Brazil, China, etc, has been a revelation for users, software and content providers alike. Users can access popular content, movies or software at speeds up to 40 times faster than they were able to before CDNs were deployed, while service providers have saved millions of dollars by reducing the load and use of their expensive international links.

Basically, a CDN caches content that is repeatedly accessed from the Internet by keeping a copy of that content on the CDN in-country, without the user having to fetch it from its source, which is generally in Europe or the US. The users' download speeds increase because the latency to reach the content has been reduced significantly, providing far more bandwidth per session. This content is typically referred to as static content - content that is not in real-time and not unique to the user.

The in-country CDN itself synchronises with global CDNs to ensure the caches have the most recent Web content to service all users' requirements in each region, achieving a fast in-country experience for the users. To synchronise their network, they use best effort Internet access, as it is economical and supports the synchronisation processes. The problem with best effort Internet is that it has high latency, high drop probability, and high potential packet loss. These three elements are generally a big no-no for delivery of business-grade applications.

Business applications, unlike static content, are dynamic and in real-time and, as a result, cannot be cached. The result is that the basic benefit of the CDN design is mostly lost on business-grade applications, which is the first problem. The second problem is that with the addition of far more latency in best effort Internet access, general levels of packet loss, which significantly affects user experience, and high drop probability in network failures, CDNs cannot deliver applications with the required performance levels.

Dynamic CDNs are more powerful and robust.

But, there is a new breed of CDN provider developing solutions to address the growing demand for enterprise application delivery. They are different to current CDN providers because they have developed the underlying network in a manner to address the application requirements. They are called dynamic CDNs.

Emerging in the late 90s, CDNs were designed with the erroneous thought that the Web was not going to handle large content transmissions over long distances. Dynamic CDNs are more powerful and robust.

The difference with dynamic CDNs that still do content caching at the edge is that they have essential elements and software in the network to enable accurate business application delivery. The most important element of the software in the global network is TCP acceleration, which reduces the effect of latency for application delivery and increases user experience. The network is no longer built on best effort Internet, but instead on low latency, zero packet loss, premium MPLS. This combination allows enterprises to get CDN-based architecture and Web app delivery worldwide, while getting unmatched application performance.

Of course, you can expect these dynamic CDN services to be far more expensive than normal CDNs because their network costs are considerably higher. Depending on your current network requirements, size, growth rate and the content you are aiming to optimise, the time to invest in a CDN may be now, regardless of the fact that CDNs will continue to improve and even decrease in price, because the performance and reliability of dynamic content is enhanced.