[Nets-seminars] NSRL talk this Friday

Richard G. Clegg richard at richardclegg.org
Mon Oct 17 10:46:11 BST 2011

This Friday's talk will be by Shi Zhou and Vasileios Giotsas from 
Computer Science.  The talk is at 16:00 in GS/302 on Friday 21st 
October.  I look forward to seeing you all there.

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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