[Nets-seminars] NSRL talk today at 16:00

Richard G. Clegg richard at richardclegg.org
Fri Oct 21 11:50:34 BST 2011

The talk will be in GS/302 at 16:00, all welcome.


Title: Inferring and analysing the Internet AS relationships
Speakers: Shi Zhou and Vasileios Giotsas

In the first half of the talk, Shi Zhou will introduce  a new approach to infer the business relationships between the autonomous systems (AS) on the Internet. The new method uses the BGP Community attribute data, which encode AS routing policies and therefore directly reflect AS relationships. Comparing with previous inference algorithms that were based on AS connectivity data, our method produces more accurate and reliable data. We accumulate monthly BGP data from a number of public sources in August 2010, February and June 2011. We are able to infer AS relationships for more than 30% of observed links, which include the majority of links among the Tier-1 and Tier-2 ASes that form the core of the Internet.

In the second half of the talk, Vasileios Giotsas will introduce some interesting results obtained from our AS relationship data. (1) We discover a number of new relationship types, namely the hybrid relationship, the partial-transit relationship, the indirect peering relationship and the backup links, which have been rarely studied but are important for the Internet routing. (2) We show that as many as 13% of AS links that serve both IPv4 and IPv6 traffic have different relationships depending on the IP version, suggesting the IPv6 topology should be studied separately. And (3) we reveal that the violation of the valley-free rule is significantly more frequent than previous estimation. Many of such violations are stable and persistent, suggesting they are not due to transient configuration errors, but caused by deliberate routing policies that put path reachability ahead of business gains. This is particularly true for IPv6.

Richard G. Clegg,
Dept of Elec. Eng.,
University College London

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