May 8, 2012

Why TCP acceleration matters to the CDN – Part 3


If you’ve already read part one and part two of this series, you should now be an expert on Content Delivery Networks (CDNs) and Transmission Control Protocol (TCP) acceleration. All right, maybe not an expert, but close. So, let’s tie it all together. As a follow-up to parts one and two, we’ll take a look at a CDN workflow use case to see why coordinated acceleration across the entire CDN is necessary to enhance performance.

The use case involves a CDN customer that wants to deliver a video file to mobile devices and PCs using Adaptive Bit Rate (ABR) technology over HTTP. The video file is originally delivered as an AVI file that needs uploading and transcoding into a format that the transmuxing platform can ingest. This upload is performed using File Transfer Protocol (FTP). The file is 150MB and is a short form, high-quality piece of content, approximately three minutes in length.

After uploading the video, it is then pushed to CDN origin servers worldwide. When this piece of content is requested from a specific location in the world (let’s say Germany), the CDN service geo-locates the individual user and routes the user’s request to the correct Point of Presence (POP). Assuming the content is delivered as HTTP Adaptive Bitrate Media, the video player chooses the specific and appropriate bitrate based on the user’s available bandwidth. The content is then transmuxed and consumed by the requesting device in Germany.

This transaction has a number of places where acceleration can occur. First, the upload of the media file can benefit from acceleration. Large media files are perfect candidates for a number of types of acceleration. However, large numbers of smaller files can also be accelerated when uploading to a CDN. Either way, acceleration helps to alleviate some of the burden associated with loading many small files or very large files. This use case is an example of ideal synchronous acceleration. However, even if only asynchronous acceleration is applied, the acceleration can make a huge difference.

Second, the movement of files to the “staging” portion of the CDN can be accelerated. Whether this is tiered origin storage or just regional origin, moving these files is onerous to the network and can, if done poorly, result in delivery delays. Most CDNs apply some form of WAN acceleration here, especially for intra-regional traffic. Again, this is an area that is well suited to synchronous acceleration since the CDN controls both sides of the transaction.

The last area is the delivery of the video to the device. This portion of the transaction is somewhat different from the other two areas because it involves a very wide variety of devices that are by nature not predictable. In most cases, there can be no client software. As a result, it’s more likely this would be a candidate for asynchronous acceleration.

In today’s environment, a poor online experience is a prescription for failure. Businesses must go further to create a rich and engaging online presence that exceeds the expectations of the customers and consumers of their content. A CDN is an effective and essential way of creating a satisfying Internet user experience. It’s a highly flexible option that addresses a wide range of needs − making it possible, for example, to simulate a broadcast video network over the Internet, cache entire websites or deliver large files to users across the globe. Market drivers such as the increase in video content, growth in Internet traffic and the proliferation of mobile devices will drive CDNs to be an ongoing study in acceleration. TCP acceleration represents an opportunity for providers to significantly increase the performance that CDNs currently provide. By optimizing each layer of the upload and delivery process, the end-user experience will be exponentially enhanced resulting in customers being drawn to content over and over again.

Ready to try out an optimized CDN for yourself? Well, we might be able to recommend one… 🙂 And as an added bonus – you can try it for free! Sign up for a 30-day free trial of Internap’s global CDN with built-in patented route-optimization and TCP acceleration.

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