Measurements and Analysis of End-to-End Internet Dynamics by Vern Edward Paxson Doctor of Philosophy in Computer ScienceUniversity of California at Berkeley Prof. Domenico Ferrari, ChairAccurately characterizing end-to-end Internet dynamics-the performance that a user actually obtains from the lengthy series of network links that comprise a path through the Internet-is exceptionally difficult, due to the network's immense heterogeneity. It can be impossible to gauge the generality of findings based on measurements of a handful of paths, yet logistically it has proven very difficult to obtain end-to-end measurements on larger scales.At the heart of our work is a "measurement framework" we devised in which a number of sites around the Internet host a specialized measurement service. By coordinating "probes" between pairs of these sites we can measure end-to-end behavior along ON 2 paths for a framework consisting of N sites. Consequently, we obtain a superlinear scaling that allows us to measure a rich cross-section of Internet behavior without requiring huge numbers of observation points. 37 sites participated in our study, allowing us to measure more than 1,000 distinct Internet paths.The first part of our work looks at the behavior of end-to-end routing: the series of routers over which a connection's packets travel. Based on 40,000 measurements made using our framework, we analyze: routing "pathologies" such as loops, outages, and flutter; the stability of routes over time; and the symmetry of routing along the two directions of an end-to-end path. We find that pathologies increased significantly over the course of 1995, indicating that, by one metric, routing degraded over the year; that Internet paths are heavily dominated by a single route, but that routing lifetimes range from seconds to many days, with most lasting for days; and that, at the end of 1995, about half of all Internet paths included a major routing asymmetry.The second part of our work studies end-to-end Internet packet dynamics. We analyze 20,000 TCP transfers of 100 Kbyte each to investigate the performance of both the TCP endpoints and the Internet paths. The measurements used for this part of our study are much richer than those for the first part, but require a great degree of attention to issues of calibration, which we address by applying self-consistency checks to the measurements whenever possible. We find that packet filters are capable of a wide range of measurement errors, some of which, if undetected, can significantly taint subsequent analysis. We further find that network clocks exhibit adjustments and skews relative to other clocks frequently enough that a failure to detect and remove these effects will likewise pollute subsequent packet timing analysis.Using TCP transfers for our network path "measurement probes" gains a number of advantages, the chief of which is the ability to probe fine time scales without unduly loading the network. However, using TCP also requires us to accurately distinguish between connection ...