Towards an Accurate AS-Level Traceroute Tool
Authors:	Z. M. Mao J. Rexford J. Wang R. H. Katz
Published:	Proceedings of ACM SIGCOMM, 2003
URL:	http://citeseer.ist.psu.edu/588954.html
Entry Date:	2004-06-30
Abstract:	Traceroute is widely used to detect routing problems, characterize end-to-end paths, and discover the Internet topology. Providing an accurate list of the Autonomous Systems (ASes) along the forwarding path would make traceroute even more valuable to researchers and network operators. However, conventional approaches to mapping traceroute hops to AS numbers are not accurate enough. Address registries are often incomplete and out-of-date. BGP routing tables provide a better IP-to-AS mapping, though this approach has significant limitations as well. Based on our extensive measurements, about 10% of the traceroute paths have one or more hops that do not map to a unique AS number, and around 15% of the traceroute AS paths have an AS loop. In addition, some traceroute AS paths have extra or missing AS hops due to Internet eXchange Points, sibling ASes managed by the same institution, and ASes that do not advertise routes to their infrastructure. Using the BGP tables as a starting point, we propose techniques for improving the IP-to-AS mapping as an important step toward an AS-level traceroute tool. Our algorithms draw on analysis of traceroute probes, reverse DNS lookups, BGP routing tables, and BGP update messages collected from multiple locations. We also discuss how the improved IP-to-AS mapping allows us to home in on cases where the BGP and traceroute AS paths differ for legitimate reasons.
Datasets:	whois data was obtained from Internet Routing Registries (IRRs). Traceroute data sets were collected from 8 locations, done to 200,000 prefixes, 2 addresses in each prefix, between May and June, 2003. BGP routing table data was obtained around May 29, 2003 from RouteViews (from 23 ASes), RIPE-NCC (from 75 ASes), SingAREN
Experiments:	Used whois data to create IP-to-AS mapping Used Origin AS in BGP routes to create IP-to-AS mapping Created improved IP-to-AS mapping with heuristics to account for affect of IXPs, sibling ASes, and unannounced infrastructure addresses Compared traceroute AS paths using IP-to-AS mappings with BGP AS paths
Results:	IP-to-AS mapping created from: whois data - better than 44% match BGP table - better than 71% match BGP table with resolution of incomplete paths - better than 77% match BGP table with resolution of incomplete paths and heuristics - better than 90% match
References:	Incongruity also observed in: Young Hyun, Andre Broido, and kc claffy, "Traceroute and BGP AS Path Incongruities," Tech. rep., CAIDA, Mar 2003.