Buyer’s Guide to Content Delivery Networks 2015
Nothing in life is entirely free, and Cedexis also offers a premium service behind the data aggregation and manual analytics that Radar.js provides. OpenMix is put forward as a load balancer; essentially it is an API into the Cedexis dataset that can automate decision-making when trying to perform tasks such as optimizing your network orchestration. Obviously, a single network can use it to spot problems, or a CDN itself can use it to choose where to deploy caches or other resources, or a publisher can use it to choose a CDN from a portfolio. I see why Mastin is keen to differentiate its broad capability from the ability of a third party to build a CDN brokerage model.
While I am sure they will all highlight their significant differences, there are other parties in this space—Conviva, Gomez, and Keynote among them. They all measure in slightly different ways and commercialize the datasets with different models. However the net effect is to measure round-trip time and throughput, then use that core KPI measurement to derive latency, time to first byte, time to last byte, availability, and more.
With those key metrics at the core of the process it becomes clearer how a CDN buyer could manually compare those core services offered by CDNs in an apples-to-apples face-off. For a given user acquiring content on a given CDN, their own ISP, and those transit and peerings between their ISP, the CDN and the CDN’s origins will all show certain latency and performance characteristics.
Know Your KPIs
For the average video consumer, latency is actually probably less important in today’s market than it once was (with the exception of time-sensitive betting video delivery applications), largely because consumers’ expectation is that they will need to wait a moment for a stream to start.
Availability and throughput are very critical; if you can’t deliver the content reliably and quickly enough, then your user experience will be poor. That is, after all, what the buyer is expecting to improve by engaging the CDN.
The derivatives of the combination of round-trip, throughput, and availability KPI measurements— combined with IP lookup-based geolocation data and path analysis—can be richly varied. But as you start to define your criteria, and can combine this with your audience targeting profile, you can begin to determine the prioritization of your CDN buying.
Mastin says different CDN customers focus on different criteria, most notably highlighting that video gaming customers emphasize throughput, being high-bandwidth applications that are typically desirable enough that viewers will put up with a few moments’ delay in start-up. In contrast, web and small object delivery companies that deliver vast arrays of complex but small bits of data are much more focused on latency.
What you choose to focus in on will vary considerably with your use case, but the good news is the data that enables you to make an informed decision is becoming abundant.
While you might still be at a stage at which you want to opt for a single CDN service and make a deliberate investment in that relationship, most CDN buyers these days hold multiple CDN accounts for several reasons, including price pressure/leverage and service availability/redundancy.
If you are moving into this model and have an increasing array of options for every delivery requirement, then full automation might not yet be a requirement or complexity that you want to invest in yet. Even so, the way that this type of automation is evolving should provide some guidance for how you should be thinking about procuring your CDN services.
In the long run, this will lead to the creation of exchanges and marketplaces—the successors to the CDN federation models—and we will keep an eye on this expectation and hope to report on it through 2015—or perhaps in next year’s CDN Buyer’s Guide.
This article appears in the 2015 Streaming Media Sourcebook as "Buyer’s Guide to Content Delivery Networks."
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