CAIDA: Cooperative Association for Internet Data Analysis


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IPv6 data used (switch to IPv4)

CCDF of AS path lengths for non-responding destinations

Use the following link to download the data used to render this graph in ASCII, comma-separated values format here: (CSV output)


This graph shows the complementary cumulative distribution function (CCDF) of AS path lengths (number of Autonomous Systems) for probes whose destinations did not respond. The path length is instead the length to the last responding hop's AS.


Examining only traces which have responding destinations gives a more accurate distribution of path lengths, but in typical usage there are several times as many probes which do not have responses. In particular, the current Ark probing strategy for IPv6 does not return enough responding destinations to create a distribution. However, the traces without a responding destination still give us a lower bound on path length distribution.


The complementary cumulative distribution function shows the fraction of collected data points that are greater than a given value. This is backwards from how percentiles are given, as those show the percentage lower than a given value. On this graph, you would find the 80th percentile at the 0.2 Y value. The AS path length is defined as the number of ASes a probe transits to reach the destination from the Ark monitor. These values are only used when a response has been received from the destination. In other words, incomplete paths are ignored for the purposes of determining AS path length.


Because most AS path lengths fall within a relatively short range, the CCDF graphs will tend to have a sharp drop off around the median. A lower median value of AS path length likely indicates that a monitor is closer to tier 1 or tier 2 providers, as it doesn't have to go through many ASes to reach its destinations.