There has been a lot of talk in the media this week about the impact that the 2012 Summer Olympic events has had on Social Networking sites like Twitter and Facebook, and real-time entertainment services such as Netflix.
Even though Netflix cautioned in their recent quarterly results that the Olympics could potentially impact their viewership, Sandvine was the first and only to report on Monday that we saw little to no impact over the first weekend of the games, a fact now reinforced by Netflix themselves online in several publications.
We certainly know that major world events can impact Internet usage, because as we reported in February, Netflix saw a 40% drop in traffic during Super Bowl Sunday, but that event was the most watched television program of all-time in the US with over 111 million viewers.
So why are several outlets running a story on Netflix traffic actually decreasing by 25%? This claim, which was unsubstantiated by any actual data, is quite peculiar – especially considering that the Olympics are getting television ratings that are less than third of this year’s Super Bowl.
What could cause such a massive error in data? The likely reason is a reliance on measurement equipment that can’t accurately inspect traffic in many common routing environments – with the problem being exacerbated by the nature of Netflix and Olympic streaming.
As we report in our Global Internet Phenomena report, Netflix is roughly 33% of all downstream traffic during prime-time in the US. Because of this volume of traffic, a large amount of Netflix’s data must be stored in a Content Delivery Network (CDN). For those unaware, a CDN is a network of computers that form a giant hard drive that stores the video, music and website files commonly accessed by users in different locations across the globe.
CDNs are important to subscribers, operators, and video providers because they play a huge role in ensuring video quality of experience (QoE), which is just one of the reasons why Netflix recently decided to launch their own CDN (after all, it’s their brand that stands to be tarnished if quality is poor).
It’s a little known fact that, while you’re watching a long video (say, a movie or television show), pieces of it actually come from several different CDNs. This means that the video traffic itself, throughout the life of the video, will actually take many different routing paths (this is synonymously known as “asymmetric routing”, “routing asymmetry” or “triangular routing”). Without care, this constant shifting of routes can cause problems when trying to perform network policy control functions (identifying traffic, protecting quality, measuring quality, etc).
In some relatively simple asymmetric routing environments, this wouldn’t pose a problem to any vendors. However, in many networks (specifically, networks in which the traffic can take three or more routes), this routing exposes a fundamental and critical engineering flaw with the “state sharing” technologies used by some vendors, leading to unreliable traffic identification and policy control for service providers relying upon that equipment. In effect, the traffic simply passes through these units without being identified as anything (we call this a “false negative”) or, in the worst case, it is misidentified as something else entirely (dubbed a “false positive”).
Since Netflix videos are typically long-lived (we’ve measured the median duration to be 42 minutes), the traffic is more likely to switch between many CDNs, so Netflix identification (and any quality measurements) is particularly error-prone to the errors produced by other vendors.
Compounding the issue is the behaviour that CDNs actively balance based on load, so a relatively short-duration, high demand event (exactly like Olympic streaming) will constantly trigger rebalancing of all traffic – further exposing the critical flaws in the “state sharing” design.
Happily for Sandvine’s customers, our unique clustering technology works accurately in any network, with any degree of asymmetric routing.
But that explanation doesn’t address why someone would publish and promote a statistic that is demonstrably false. Several sites have already posted responses from Netflix that strongly refute the purported decline, and at least one (The Atlantic) has posted an entire article openly questioning the 25% figure.
At Sandvine, we have been publishing our Global Internet Phenomena Report for over 10 years, and in that time we have become the most trusted source on the latest facts, fads, and future trends impacting fixed, mobile and converged networks across the globe. For us, the impact of the Olympics on North America’s networks is interesting not only because of the impact it could have on traffic during prime-time, but the impact live streaming has on off-peak hours due to the five to eight hour time difference with London.
Below is an example of some of Sandvine’s rich and accurate network-level reporting capabilities that we have helped enable on a US fixed-access network with a national footprint.
The first chart shows how traffic levels related to Olympic streaming have fluctuated over the past three days.
The chart below then takes a deeper diver and visualizes the traffic levels of each stream offered by NBC Live Extra on August 2.
To make it easier to appreciate the impact of particular events, in the third chart we’ve pulled out the top 5 streams from yesterday and plotted them in overlapping lines.
On first glance it appears that the women’s gymnastics all-around final was the most viewed event online, in actuality it was the men’s 200 individual medley. NBC actually offered two streams of the event, one stream (green) for just the Michael Phelps and Ryan Lochte related races, and another (red) which actually streamed all of the day’s swimming events. The US men’s basketball game also received the dual stream treatment with some viewers turning into the dedicated stream, and others watching on the simulcast of the NBC Sports network.
For the remainder of the games I will be keeping an eye on how the Olympics are impacting Internet traffic around the world, so be sure to check back regularly for the latest news from London.
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