Posted by Colin Dixon
On Monday, Qwilt and Limelight networks announced a partnership to work together to optimize the delivery of Internet video to consumers. Limelight, of course, is one of the major CDNs providing long-haul video distribution services. Qwilt provides transparent caching and video delivery solutions. Transparent caching might sound like an obscure technology, not relevant to regular mortals. However, it is a critical component that can help the Internet scale to Super Bowl sized audiences online. Not only that, it benefits ISPs, content streamers and consumers. To find out why, read on.
So, what is “transparent caching” and why is it needed? When a user requests to watch a TV show on his tablet the video is streamed from a server in the cloud directly to his device. If another iPad requests the exact same video from the same server at the same time, another video stream is created and sent to the new device. That means, if the server is in Iceland (and, believe it or not, many are to save on cooling costs) and the two requestors are in the same street in California, two separate video streams are sent all the way across the Internet carrying exactly the same video. This is called point-to-point delivery.
Now take this idea and multiply it by the millions that watch the Super Bowl: millions of streams all carrying exactly the same thing. This is why the Internet can’t handle the Super Bowl online today. That is where transparent caching comes in. The cache, a computer with some storage attached, sits in the local network watching all the video traffic going by. It sees all the requests for the Super Bowl and starts to store the video. When someone else in the local area requests to watch the game, the cache intercepts the request and streams it to the requestor directly. Suddenly, all those point-to-point streams stretching all the way to Iceland are served locally freeing up a lot of Internet bandwidth for other things.
Saving bandwidth like this helps everyone. The ISP doesn’t have to pay as much for its connection to the Internet backbone. Content providers don’t need to pay as much in bandwidth charges to deliver the video. Consumers get a better experience because a local video stream is less prone to degradation due to network problems.
I should mention why the word “transparent” is used, because it’s very important. A transparent cache treats all video (actually, all traffic) exactly the same. It just looks for the most popular content, stores it locally and streams it locally when requested. No service is favored over another. This is critical if net neutrality is to be maintained. An ISP can install a transparent cache, see the benefits in reduced bandwidth requirements and improved quality of experience to customers without being accused of favoring one service over another.
Why is Limelight working with Qwilt when they are in the business of charging for bandwidth? I put this question to Dan Sahar, VP of Product Development at Qwilt. He said that this partnership is an early sign of new business models between ISPs and Limelight. CDN’s sell bandwidth and, to a certain extent, price is the major differentiator. Transparent caching ties the CDN and ISP together more closely as equipment is placed directly in the ISPs network. Such an arrangement makes the CDN much less easy to replace.
Why it matters
The explosion in video consumption online will inevitably lead to bandwidth problems. Solutions need to be put in place now to address the issue.
Transparent caching technology, such as provided by Qwilt, will be an important part of the scaling solution.