It depends on whose numbers you like. Andrew Odlyzko claims it’s up 50-60% over last year, a slower rate of growth than we’ve seen in recent years. Odlyzko’s method is flawed, however, as he only looks at public data, and there is good reason to believed that more and more traffic is moving off the public Internet and its public exchange points to private peering centers. Nemertes collects at least some data on private exchanges and claims a growth rate somewhere between 50-100%.

The rate of growth matters to the ongoing debates about Internet regulation. If Odlyzko is right, the rate of growth is lower than the rate at which Moore’s Law makes digital parts faster and cheaper, so no problem, routine replacement of equipment will keep up with demand (leaving out the analog costs that aren’t reduced by Moore’s Law.) If Nemertes is right, user demand outstrips Moore’s Law and additional investment is needed in network infrastructure. Increased investment needs to be covered by government subsidies or by the extraction of additional value from the networks by their owner/operators. Subsidy isn’t going to happen while the economy teeters on the edge of collapse, so the high growth conclusion argues against regulations designed to preserve the legacy service model. It’s a vital question.

A couple of new data points emerged this week. Switch and Data, operator of PAIX public exchange points in Palo Alto and New York, says its traffic grew 112% last year:

International networks are making the decision to peer in the United States to reduce transit time between countries and accelerate the performance of U.S. and other global websites in their home markets. This is important due to the explosive growth of Web 2.0 with its bandwidth intensive websites for social networking, rich digital content, and business software applications. Exchanging traffic directly between content and end user networks also significantly reduces Internet transit expense which has been a rapidly growing cost for companies as their traffic volumes soar.

At the Switch and Data New York peering center, traffic was up an astonishing 295%.

Combining these numbers with what we know about the Content Delivery Networks that deliver as much as half of the Internet’s traffic, I think we can reasonably conclude that comprehensive measurement of Internet traffic would support the theory that traffic still grows at an increasing rate. One side effect of the increased use of CDNs and private peering is less certainty about the overall state of Internet traffic. Studies confined to public data are less and less useful, as many researchers have been saying for years.

At any rate, there’s considerable uncertainty about this question at the moment, which argues that the Internet needs a Nate Silver to pierce the fog of conflicting polls.

Network inventor Richard Bennett originally posted this article to his Broadband Politics blog.