Content Delivery Network (CDN) Management and the Cost of Success


Recently the Broadcasting Board of Governors (BBG) awarded a new CDN contract.  The previous CDN contract was fixed price–regardless of usage.   The newly awarded contract is not fixed price–it’s usage based.  As a result, BBG must quickly adapt a central strategy to better manage its CDN.


The 24 Petabytes Served Club

CDN contracts are generally usage based, priced per gigabytes delivered per month.   Years of being on a fixed price contract left us not so concerned about tracking total delivery volume every month.  After all, gigabytes served are not necessarily a key metric for success.  For example, video content bit rates have increased thanks to bigger last mile connections and consumer demand for HD-quality video over the web.  Your CDN bill may have exponentially grown over time while viewer numbers remained static.

Now on a traditional usage based contract the first question was, “How much have we been delivering?”  The next question was, “Based on past delivery volume growth, can we estimate our future growth?”

Delivery Volume (GB)

Delivery Volume (GB)

Delivery Volume (GB)







Delivery grew 88% and 29% through 2010-2011 and 2011-2012, respectively.  Can we estimate future growth based on the past three years?  Is delivery growth slowing year over year or can we more carefully plan our delivery?


Not all Gigabytes Are Created Equal

The cost model for CDN services is simple.  Like cell phone usage plans there is generally a base commitment charge for a set volume of data served.   Overage fees are negotiable and currently range between 5 to 10 cents per GB.  If you are a big media organization monthly commit amounts can be waved while getting the most competitive per GB delivered rate.  However, be aware that not all GBs served are delivered at the same flat rate.

For example, vast enterprise media organizations like the BBG serve many types of content over an eclectic mix of protocols and technologies from legacy to the latest premium services.  An inventory of BBG old and new content delivered through the CDN yielded close to 500 digital properties assigned to different delivery categories.

Delivery groupings with potentially varying costs per GB were as follows:

Delivery Type  Service / Cost
Basic Website Caching Basic CDN Service / Low Cost
HTTP Downloads Basic CDN Service / Low Cost
FTP Downloads Basic CDN Service / Low Cost
Site Acceleration Premium CDN Service / Higher Cost
Legacy Streaming Live & On-Demand
(real, winmedia, quicktime, shoutcast)
Basic CDN Service / Low Cost
Flash Media Server Streaming
(adaptive live and on-demand)
Increasingly Basic depending on CDN contract but you may be still charged more than basic delivery.
HTTP Streaming / Chunking
(Apple IOS and html5 adaptive delivery)
Premium CDN Service / Higher Cost
Mobile Detection and Delivery Premium CDN Service / Higher Cost

Our inventory quickly found that we were delivering basic content like http audio and video downloads using site acceleration.  Site acceleration as defined by our current CDN provider only marginally improves listener/viewer experiences on the web through straight http audio and video progressive downloads.   In other words, paying a premium price for what  should be served through basic delivery is CDN mismanagement.


Future CDN Management and Services

Competing technologies and advancements continue to make CDN management more complicated but always with the promise of simpler days ahead.  For example, the elimination of streaming servers and a myriad of streaming protocols (rtsp, rtmp, mms) will be replaced by http.  In a few years there will be one streaming technology  categorized under a basic, low cost delivery charge.

However, the evolution of html along with the proliferation of web-enabled devices will seed new, unforeseen premium delivery services.  Early adopters will pay-up for a nanosecond of competitive advantage.   As a result, one base delivery charge will remain an unrequited dream for CDN managers.  They will still need to diligently manage the cost of delivering their content.

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Doug Zabransky

Doug Zabransky

Doug Zabransky is the Technical Services Manager for the Office of Digital & Design Innovation.

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