Andrew Blum

Author of Tubes: A Journey to the Center of the Internet
Andrew Blum, author of Tubes: A Journey to the Center of the Internet, on how data moves, and what slows it down.

Interview transcript: Andrew Blum

A lot of things get in the way of the flow of data. For example, I went to visit the lab at one of the major manufacturers of routers, and one of their biggest bugaboos is how slow the switching is compared to their two benchmarks, which are the speed of light and the speed of light through a fiber, which is ? the speed of light. Theoretically, data should be able to cross the US in 40 milliseconds or so, and then that last meter through the router is the equivalent of walking 15 minutes to get to the Post Office and then waiting for five days.

The bottleneck basically consists of the back and forth necessary to read the packet, look up its address, and then figure out which exit to go through to end up at the next destination. Every router has a finite number of ways out the door, but directing the data out the right way requires the full routing table.

Although we associate the internet with almost infinite mobility — the end of geography, in a sense — in fact, its infrastructure is relatively fixed. There is always going to be a transport cost, which means that location is going to matter. In the same way that it's cheaper to fly to LA than it is to fly to Louisville, because of all of the reasons that we all already know — supply and demand, and capacity on that route — the same is true with the transport of data across the internet. We're mostly insulated from it as urban internet users, but the exceptions to that are really powerful. One exception is Australia, where, for regulatory and monopoly reasons as well as geographic and infrastructural ones, you as an internet user are severely constrained in the way that you use the internet. The other is rural broadband. The conventional wisdom there is that the last mile — wiring people's homes in sparsely populated areas — is too expensive. Actually, often it's the middle mile that is too expensive — it is just so much more expensive for a local ISP in a place like Cheyenne, Wyoming, to get sufficient capacity to connect back and forth to the rest of the internet, which, geographically, probably means Denver.

But once you have a strand of glass between two places, you can shine any amount of light through that glass. In other words, we need to build the tubes, but once the physical glass connections are in place, the capacity of data through that network is limitless — depending on what sort of equipment you put at the ends of it.

It's completely different from a road, where you might build a six-lane highway and then figure out ten years later that you really should have gone for twelve. Once you put the glass in, it's the right size. The technology of cramming multiple wavelengths of light through a single fiber, and the increasing ability to cram higher and higher data rates through a single wave of light, allows, at the moment, with some cost, practically infinite capacity for every single fiber.