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How Much Data is Being Consumed and Should I Care?

My previous article (The Adaptive Nature of Netflix, 2/23/2012) explored the nature of the Netflix service from the perspective of traffic throughput. Netflix does a nice job of dynamically throttling video streams based on a number of factors. This article is going to turn things around and focus on the other half of the story by looking at how much data is actually consumed when using different streaming video services. When evaluating Internet services, the primary focus is typically on speed, which is what ISPs emphasize in their advertising. However, the issue of pure data consumption is quickly becoming the most important agenda topic for ISPs as they debate the best approach for delivering profitable services.

NetForecast has been tracking Internet traffic trends for more than 20 years. Based on collected data, it estimates that US-based Internet traffic has been growing at a CAGR of 50% over the last 10 years.

Carriers' tracking and monitoring of data consumption is not new. Cellular providers have been doing this for years. As a result, cellular users are conscious of how much data they use, and are careful not to exceed their monthly data plans, or risk paying pricey overage penalties (see this recent post by Martha Buyer).

ISPs as well are becoming increasingly conscious of the continued increase in data consumption and the impact on their networks. As a result, they are aggressively investigating ways to implement data usage plans, similar in concept to the cellular providers.

So what is driving traffic up? Over time, NetForecast has tested a wide range of applications and has determined that streaming video generates the largest amount of data. The way it works is that extremely high amounts of data are consumed right at the beginning in order to fill the buffer, and then the flow levels off, and just enough data is requested to keep the buffer full.

Watching a one-hour Netflix movie can consume close to 1GB of data. However, a more pervasive use of streaming video is the viewing of short clips (YouTube) and movie trailers (Flixster) using a favorite pastime called "video surfing." A user will bounce around until they find something interesting, which triggers a substantial download for each video, regardless of whether the entire content is even watched!

Another point that needs to be made is that ISPs are not the only victims of this usage pattern. Enterprises have plenty of users who "sneak" a peak at YouTube during work or try and decide what movie they should watch later that evening.

The following chart summarizes the amount of data that is consumed after a video is requested but before the video begins playing. The chart includes examples from three popular streaming video services.

At first glance, the data volume seems small, averaging between 10MB–20MB. However, watch what happens in the following scenario. Let's assume that two users at work spend 20 minutes "surfing" the Internet. The first user views 15 different web pages, with an average page size of 1.4MB. The second user watches four YouTube videos (2 @ 15MB & 2 @ 37MB) and two Flixster trailers (1 @ 17MB & 1 @ 40MB). The following chart now tells a very different story.

Multiply the amount of data generated by video surfing over the course of a month times the number of users at your site and we are talking massive amounts of data. The topic of data consumption is not going to fade away. I think we are in for some interesting changes that are sure to shake up the industry.