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Center for Applied Internet Data Analysis
AS Path Lengths
How far does the average packet travel on the Internet?
We have attempted to answer this question by estimating the number of Autonomous Systems that packets cross between their source and destination networks. Our analysis is based on a packet trace collected from FIX West, and routing information reported by the U.O. Route Views project[Meyer97]. The packet trace used for this analysis was taken on May 18, 1998 at 11:06 PDT, and it ran for approximately 11 minutes. It contained 21,937,821 packets from 15,006 different source networks and for 21,059 different destination networks. The trace was collected by Hans-Werner Braun from one of the four OC-3 links interconnecting FIX West and MAE West in San Jose, CA.

Estimating the AS path to the source and destination addresses for each packet requires a core routing table as close to the measurement location as possible. We used the routing information advertised from the peer of the U.O. Route Views server that was closest to packet sampling point. This routing table included 49,074 routes originating from 3526 different ASes. In the histograms below, we plot the sum of the source and destination AS path lengths as the estimated number of ASes traversed.

Note that although we estimate AS path lengths using a methodology quite different from that used in (no longer available), the results are strikingly similar. The previous work was based exclusively on topological information derived from BGP routing tables. This new result confirms the previously predicted result with an analysis based on actual Internet traffic flows rather than the static topology of routing table snapshots

Autonomous System Path Lengths graph


1. [Meyer97], University of Oregon Route Views Project,, Advanced Network Technology Center, David Meyer (now at Cisco Systems).
Thanks to Hans-Werner Braun and NLANR/MOAT for supplying the packet trace data, and David Meyer for maintaining the Route Views project.
Sean McCreary and kc claffy, 5/25/98
  Last Modified: Tue Jan-8-2019 13:43:15 PST
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