May 19, 2011, 6:02 PM — A report issued Tuesday showing Netflix makes up a third of total Internet traffic is inaccurate enough – or at least the reports about it are inaccurate enough – to show not very many people in either the press or vendor marketing understand the network they base their business on.
There are two important points here, both relevant to people who do IT for a living, not just those who either dislike data caps or do like Netflix:
First, the report didn't say Netflix eats a third of the whole Internet; that assumption was off base enough to prompt Forbes to run a piece trying to correct it, but not quite succeeding.
Sandvine – an Ontario-based networking vendor – issued a report Tuesday estimating that streaming media from Netflix make up 30 percent of downstream traffic during peak times.
What Sandvine meant was that Netflix traffic spiked heavily during prime time – when most people are home and watching something other than what's on TV – but only across the last mile.
TechCrunch posted some graphics showing what's travelling across the nation's networks during peak times, and in what volumes. Netflix comes out on top, but only with the caveats below.
Netflix uses content-distribution services to make sure its content is located close to customers, so when you click Play the file you see is being downloaded from somewhere nearby, not from Netflix' central database.
The portion of the network Netflix hogs is only the ISP's edge connections – from a distribution hub to the house of Netflix' subscribers.
The heaviest traffic is in spikes during one part of the day, which is irrelevant from a network-infrastructure standpoint. Even if the spike is only an hour, the network segment through which the spike passes still has to have enough capacity to handle it.
For the ISPs that is the good news, though they already know this and simply leave the good news out when complaining they must be allowed to throttle Netflix to avoid having their networks swamped.
Netflix doesn't swamp the ISPs' backbones or even their high-volume network spokes because its content is distributed and cached ahead of time. When it launches it travels only across the edge, vastly reducing the logic behind arguments by AT&T, Comcast and Verizon that they have to keep adding to their core networks to keep up with bandwidth-sucking competition from Netflix.
The second point that's relevant for working geeks is that the level and reasoning behind data caps from AT&T and other ISPs vastly understimates what a "normal" level of Internet use really is.