We advocate the use of certain dimensionless metrics, depending on the ratio of RTT over distance, to measure the quality of Internet paths. We have analyzed several independent samples of Internet paths, finding that the statistical distributions of these metrics are quite simple and show power-law tails. Understanding the exponents of these tails is of special interest to model-building. We exhibit the results of numerical simulations on very simple models that reproduce to some extent the general features of these distributions. While not yet sufficiently realistic, these models suggest some of the mechanisms that may be shaping the large scale behaviour of the Internet.
