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With video services delivering massive amounts of data globally, a robust and agile CDN switching setup is an essential component in the delivery stream for all major players in the industry. But like the skinning of cats, there is more than one way to switch CDNs on the fly. Here we break down the pros and cons of the three principle methods.



How it works:

The URL of the service is indicated by a DNS routing switch that consists of the content (video title) and the base (depending on the current CDN).

Pros & cons:

Working at the DNS level, setup can be integrated without modifying the app. However, traffic analysis is limited because the app gets no data on the CDN, and with the base of the URL changing (and possibly the parameters, as well) at every CDN switch, this can cause havoc during live streams.



How it works:

Third-party software within the user’s player makes the decision to switch CDNs taking into account QoE metrics for that user such as CPU or memory performance.

Pros & cons:

It’s a simple solution, but a black box with risks that outway the benefit. When a plug-in is left to make these serious business decisions without a wider understand of network load, it may choose a CDN that does not match the goals of the distributor. Bad decisions can also impact other “middlemen” and negatively affect delivery performance. What’s more, plug-ins also require updating whenever a customer adopts a new player.



How it works:

In the case of SmartSwitch, NPAW’s API, the client or server asks which CDN is best for a given IP and device. SmartSwitch applies an algorithm previously configured by the customer and suggests an ordered list of possible CDNs. The customer’s API will then choose the CDN and redirect data flow. SmartSwitch draws on end-user data from around the world to continuously learn, monitor and predict the best routes for a given request. It can even be optimized with a hierarchy of preferences by geography, ISP, time of day and quality metrics based on a customer’s data or by CDN performance across the industry.

Pros & cons:

CDN switching with an API is inexpensive to set-up, benefits from QoE data and is more flexible than the other options. Although setup takes a bit more effort, once in operation the API solution is fully scalable and can painlessly integrate new players as it functions at the server level. This setup also allows for communication to go from client-to-server to server-to-server, a method prefered by industry leaders. Since the slimmed down plug-in involved in an API setup only collects data and does not make decisions, there is minimal code while the right switching decisions are made to maximize speed with minimal risk to network stability.

Research & Editorial Team on January 18th 2018

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