Content Delivery Pricing: Understanding CDN Overages

I’ve seen numerous reports lately by some in the financial community talking to “bursting” overages by CDN providers. Many of these references talk to overages incorrectly and some analysts might benefit from better understanding the two different ways CDNs charge for their services and exactly how “bursting” fees play into a CDNs bottom line.

The most recent example I read was coverage put out on Akamai where the analyst downgraded the stock based on their feeling that Akamai would not be able to get as much additional revenue for “bursting” overages as they have been getting in the past, due to the recent pricing pressure in the CDN industry. As the analyst stated, 30% of Akamai’s total company revenue comes from what he called “bursting”. That may be the case, but “bursting” and overages are not the same thing, especially when you’re talking about content delivery for video.

The first thing to realize is that no one knows exactly what Akamai products the 30% in overages comes from. Too many assume it’s from the delivery of video, but in most cases it isn’t. It comes from many of the other products and services Akamai offers like static caching, software downloads and application delivery. I asked Akamai for a breakdown of what products accounted for what percentage of overage revenue but they said it was not data they were making public.

Even without Akamai making that data public, all analysts should know the two different ways that all CDNs charge and how overages work. Every CDN charges for delivery of video, via streaming or download, based on two metrics. One is the total amount of Mbps sustained at any given time, over a 95th percentile. The second in the total GBs delivered over the network in any given month. These are two very different metrics with very different overage charges.

The majority of customers for video delivery have contracts where they are paying for the amount of GB delivered over the course of a month. With this model, there are rarely overages as typically when you push more bits then you signed up for, you get charged a lower per GB fee. For example, if you committed to push 100GB in a month and are paying $1.00 per GB, and then end up doing 150GB, typically your pricing then drops to a lower rate, say $0.95 per GB. Rarely do CDNs charge overages on a per GB delivered model and in many cases, some of them charge one flat fee per GB no matter how much you push. Years ago, CDNs use to charge overages with this model, but quickly realized that by doing so they gave customers no incentive to push more traffic on their network. This was how Speedera Networks really got traction in the market, by taking all the overflow traffic from customers who didn’t want to pay overages with their core CDN.

The other way CDNs charge for video delivery is on a per Mbps sustained model. This means that you pay for the volume of traffic you push at any one given time, and not based on the total bits pushed. Typically, this is the pricing model where you are charged for overages above the volume of Mbps sustained that you commit to. It’s also referred to by many as 95th percentile as with this model you are typically allowed to burst over your committed Mbps allotment for less than 5% of the month with no penalty.

There are a few reasons why understanding these different pricing models are important. For starters, don’t assume that you know what products the CDNs are getting overages from. Two years ago, Akamai stated that less than 10% of their contracts for the delivery of video were on a per Mbps model, the rest were per GB pricing. I don’t know what that number is today since Akamai won’t say, but too many are assuming that the 30% in revenue is from CDN for video when it isn’t. Much of what Akamai delivers is content of various types, static images, software, applications and video. When it comes to delivering the majority of content other than video, they are charged on a per Mbps sustained model where overages apply. So to assume that Akamai could take a hit in future overage revenue is to assume that they are seeing 30% of that revenue from video delivery, which they aren’t. How does Akamai compare to Limelight Networks in terms of contracts? Hard to know since we don’t know the Akamai number, but Limelight said on their road show that 40% of their customers have per Mbps sustained contracts.

So why does any of this matter and why do money managers pay so close attention to how much Akamai is making in overages? Simple. There is a fixed cost to any CDN to deliver bits of content and if you can charge two or three times that in overages, then that greatly affects your P&L. It all comes down to the bottom line.

That being said, this is not a prediction on my part of how any company’s stock price will perform now or in the future. I am not a financial analyst and have no vested interest in any company’s stock.

  • While the number of contracts for the delivery of video on a per Mb model may only be 10% and 40% for Akamai and Limelight, I bet that a large majority of the video traffic is billed that way.
    I have spoken to folks who now blend their traffic between both models as a way to reduce their costs. Publishers are getting savvy about when to use each.
    Currently, these folks use multiple providers to achieve this but perhaps CDNs may offer this blending with one contract.
    This, as well as increased competition from new CDNs and other models like hybrid-p2p, is substantially reducing the delivery costs for publishers.
    Disclosure: I work for VeriSign

  • Parsing CDN Pricing Reports

    There was confusion among some CDN market watchers about Level 3’s new pricing and how it impacts Limelight (LLNW) and Akamai (AKAM).

  • John

    We used several CDNs in GB and Mbps modes. PayPerGB is interesting when you have spiky traffic. But traffic is expensive. PayPerMbps is cheaper but more dangerous because of the +5% spike risk.
    We now use a hybrid model using Streamzilla. Where we pay a very low flat fee for 2Gbps and PayPerTB for overflow traffic. As far as I know Streamzilla is the only CDN that worked out this model. Anyway, it’s cheaper and better to control costs.

  • Thanks for the explanation of the pricing models and overage charges. It’s the best writeup on the subject that I’ve found on the web.