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Advancements in the Inference of AS Relationships

Advancements in the Inference of AS Relationships. Xenofontas Dimitropoulos (Fontas) (CAIDA/GaTech) Dmitri Krioukov Bradley Huffaker k claffy George Riley. Outline. Background & previous works. Limitations of existing algorithms.

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Advancements in the Inference of AS Relationships

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  1. Advancements in the Inference of AS Relationships Xenofontas Dimitropoulos (Fontas) (CAIDA/GaTech) Dmitri Krioukov Bradley Huffaker k claffy George Riley

  2. Outline • Background & previous works. • Limitations of existing algorithms. • New algorithm to infer customer to provider (c2p) peer to peer (p2p) and sibling to sibling (s2s) relationships.

  3. Motivation • Evolution of the Internet. • What are the economics of the Internet and their role in shaping it? • Connectivity doesn’t mean reachability. • AS relationships determine the valid paths along which packets can flow. • Finding a provider or peer for ISPs. • Details of peering relationships aren’t widely available. • Want to make a more informed decision based on actual relationships and connectivity instead of “brand name”. • Determining AS rank. • What is the relative importance of the Internet players? • Useful for determining order for security notifications.

  4. Peer-peer link Customer-provider link 209 701 Customer-provider links 70 12 13 Valley-free model • AS paths have the following hierarchical structure: • zero or more customer-provider (or sibling) links. • zero or one peer-peer link. • zero or more provider-customer (or sibling) links. GAO: “On Inferring Autonomous Systems relationships in the Internet” L. Gao ACM IEEE Transactions on Networking 2001.

  5. Previous Works • GAO • Based on hierarchical property of AS paths. • Use AS degree to find top of the hill and assign transit relationships to the side-hill links. • SARK • Introduce the Type-of-Relationships (ToR) problem:Given an undirected graph G derived from a set of BGP paths P, assign the edge type (customer-provider or peering) to every edge in G such that the total number of valid paths in P is maximized. • Provide a heuristic solution. SARK: “Characterizing the Internet hierarchy from multiple vantage points” L. Subramanian et. al INFOCOM 2002.

  6. Previous Works • DPP and EHS: • No peering can be inferred in ToR. • ToR is NP-complete (by reducing to MAX2SAT). • Mathematically rigorous approximations to ToR. DPP: "Computing the types of the relationships between Autonomous Systems", G. Di Battista et al. IEEE INFOCOM 2003. EHS: “Classifying customer-provider relationships in the Internet”, T. Erlebach et al. IASTED CCN 2002.

  7. 701 209 70 18 12 13 ToR limitations • ToR does not provide a deterministic solution, because some links can be directed either way and produce the same number of valid paths. • ToR solutions may treat anomalous paths as valid, which results in incorrect AS relationships. • BGP misconfigurations and complex polices can violate the valley freemodel.

  8. Our customer to provider algorithm • Generate Input: • Produce AS graph (with no relationships). • Assign weight to edges based on node degree. • Formulate c2p inference as a multiobjective optimization problem: • O1: Maximize number of valid paths. • O2: Maximize the sum of weights over all edges. • Intuition: • Paths are now colored by their edges weights which allows to detect anomalous paths. 701 209 701 209 W = 0 W > 0 70 70 18 12 18 12 13 13 Valid with small weight Invalid with large weight

  9. Work in progress • Inference of p2p links. • Inference of s2s links. • Validation of links. • Create AS Rank based on AS relationships.

  10. Thanks! ? Inferring AS Relationships: Dead End or Lively Beginning? 4th Workshop on Efficient and Experimental Algorithms (WEA), 2005. http://www.prism.gatech.edu/~gtg053c/asrelationships.pdf

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