Representing the Internet as a succinct forest
Effective placement of resources used to support distributed services in the Internet depends on an accurate representation of Internet topology and routing. Representations of autonomous system (AS) topology derived solely from routing tables show only a subset of the connections that actually get used. However, in many cases, missing connections can be discovered by simple traceroutes. In addition, the differences between customer-to-provider links, peer-to-peer links, and sibling-to-sibling links are useful distinctions. We first apply a clustering algorithm to simplify the AS graph to an AS forest. Then we use two complementary mechanisms to improve accuracy of an AS forest as a predictor of packet paths. One mechanism uses recent insights that packets flow unidirectionally across customer-provider inter-AS links. Annotations are added to the AS forest to indicate links that appear to be peering versus those that appear to be customer-provider links. The other mechanism provides links between trees by remembering the most recently seen similar traceroute.