Advancements in the Inference of AS Relationships

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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.

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Motivation

• Evolution of the Internet.
• What are the economics of the Internet and their
  role in shaping it?
• Connectivity doesnt mean reachability.
• AS relationships determine the valid paths along
  which packets can flow.
• Finding a provider or peer for ISPs.
• Details of peering relationships arent 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.

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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.

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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)
  problemGiven 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.

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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.

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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.

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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 gt 0
70
70
12
18
12
18
13
13
Valid with small weight
Invalid with large weight
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Work in progress

• Inference of p2p links.
• Inference of s2s links.
• Validation of links.
• Create AS Rank based on AS relationships.

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Thanks!

• ?

Inferring AS Relationships Dead End or Lively
Beginning? 4th Workshop on Efficient and
Experimental Algorithms (WEA), 2005. http//www.pr
ism.gatech.edu/gtg053c/asrelationships.pdf