Temporal properties of routing

To better understand some of the temporal properties of routing, we compare the distribution of the distance ratio computed from our 2000 data set with that computed from Paxson's 1995 data set [20]. The paths in the 1995 data set correspond to traceroutes conducted amongst the 33 nodes (mainly at academic locations) that were part of the testbed. We considered 340 paths between the subset of 20 nodes that were located in the U.S. The 1995 data set includes multiple traceroute measurements between each pair of hosts. In our study, we only use data from one successful traceroute between each pair of hosts. To keep the nature of the measurement points similar, in the 2000 data set we only consider paths between the 15 source hosts located at universities and the 265 hosts in the UnivHosts set.

Figure 7: CDF of distance ratio for paths in Paxson's 1995 data set and our data set from 2000.

Figure 7 plots the CDF of the distance ratio for the 1995 and 2000 data sets. By observing the tail of the cumulative distribution, we find that the distance ratios tend to be smaller in the 2000 data set. This improvement is not surprising because the Internet is more richly connected today than it was 5 years ago. There now exist direct point-to-point links between locations that were previously connected only by an indirect path.