Internet traffic: visualization, discovery, and very large displays

Abstract

For a decade, the ruling common wisdom for Internet traffic held that it was everywhere bursty: over periods lasting tens of milliseconds to hundreds, the traffic was either much below its average rate or much above. In other words, the traffic was not smooth, not staying at all times close to its average. It was bursty on the cable running down a street, carrying the merged traffic of a small number of cable modem users in one section of a town. It was bursty on the core fiber of an Internet service provider, carrying the merged traffic of thousands of users from all over the country. The Internet was designed to accommodate the bursty traffic. The routers and switches that forward traffic from one place to the next were designed for burstiness, and Internet service providers allocated traffic loads on the devices based on an assumption of burstiness. Recently, it was discovered that the old common wisdom is not true. Visualization played a fundamental role in the discovery. The old wisdom held up for links with a small numbers of users. But as the number of users increases, the burstiness dissipates, and the traffic becomes smooth. Design of the high-load part of the Internet needs to be rethought. The old wisdom had persisted for high-load links because the databases of traffic measurements from them are immense, and the traffic measurements had not been studied in their fullest detail, which is necessary to see the smoothing. Visualization tools allowed the detail to be seen, and allowed the verification of a mathematical theory that predicts the smoothing. To see the detail, individual visual displays were created that take up an amount of virtual screen real estate measured in hundreds of pages. It is a simple idea: if you have a lot of data, and you want to see it in detail, you need a lot of space. What is needed now is a rich set of ideas and methods for navigating such very large displays.