A Buyer’s Guide to Content Delivery Networks
Another thing has changed over the last 15 years: A decade or more ago, a publisher would only have one CDN service. Increasingly today, publishers will have multiple CDN accounts for better resilience to network outages and because sometimes one CDN’s edge locations are closer to specific customers that another cannot reach quite as well.
To feed into this, there are macro-CDNs, which actually do not “do the delivery” but rather measure your chosen CDN services constantly and reroute your users’ requests to the CDNs on-the-fly based on the current measurements and logic. This makes the underlying CDNs work harder to get deeper into the network and deliver the content as well as possible, while maintaining the business logic that you want as a large CDN customer. Customers can choose based on a combination of preference among latency, price, and availability.
Factors CDNs Will Put Forward
- Faster load for webpages
- Faster start for audio and video streams
- Better peak load scale and management
- Responsiveness (ability to transform/treat/transcode your content as new devices and software comes to market and attempts to access the content)
What to Look For: An Insider’s Perspective
While penning this article, I happened to have a coffee with a friend and former colleague from my own CDN, Steve Miller-Jones, who is now focused on optimizing Limelight’s performance.
I asked him to (as far as possible without plugging Limelight capabilities) give me a heads-up on the features to look out for in today’s CDN and also to comment in more generic terms about what makes the delivery of a digital presence successful. The following are a collection of his thoughts:
Today’s content delivery challenges are not just faced by CDNs.
HTML pages are heavier, images richer, and there are more videos than ever before. And there is a big, mobile audience. You could buy a circuit and connect it to your server, but there are many websites vying for the same users, competing for the same bandwidth. Delivering any of your digital presence using the public internet for more than the first and last miles is like hitching a ride -- you don’t know the driver, you don’t control the route, and you may need to change drivers along the way.
The barriers to entry in the CDN market have lowered, slightly. Generic, high-speed hardware is cheaper. Shared hosting is available. It is possible to peer and access transit globally. Hosted and cloud services could run operational and back office tasks.
There are more service providers offering content distribution services, but I hesitate to call them all networks. The true barrier in the CDN market is scale -- managing small content libraries for a few B2C content distributors by simply putting it all into every cache everywhere doesn’t mean that a service provider can handle many large libraries and maintain high, global availability and throughput for the long-tail.
Operating an overlay-caching model on top of networks you don’t manage is very different from running an owned and operated network content distribution model. I urge readers to consider how service providers are architected when buying services. It is fundamental to effective service delivery, scale, and optimization.
Here are some important video delivery features to look for:
- Time to publish -- Your storage and transcoding solution shouldn’t get in the way of you meeting your publishing deadline. Will the next viral video wait for a transcoding process?
- Storage -- Consider storing content in multiple edge locations as close to the user as possible. When content isn’t in cache, this will decrease the time users wait for the first scene.
- Protection -- DRM should be part of any video solution. If you aren’t using a video platform, your storage and delivery solution should offer workflow steps to integrate with security and DRM services.
- Service selection -- Do you deliver the same content from different service providers in different regions? If so, you need a DNS service that offers percentage-weighted
- policies for traffic distribution at the granular level you need.
- Delivery optimization -- Different distribution tactics require different CDN configurations such as chunks versus byte-range requests. If your provider tells you that it does not make a difference, that’s because they only have one way of doing it. Expect and require more.
As a content distributor or content owner, you want to be sure that the tactics used to deliver your content are optimal for the types of delivery you need. The benefits of establishing good delivery tactics for each format and media type with your CDN will protect your revenue generation capability, provide the best performance capabilities for your content, and meet demanding user expectations for your digital presence.
This article appears in the 2014 Streaming Media Sourcebook as "Content Delivery Networks."
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