Advancements in the Advancements in the Inference of AS Inference of AS RelationshipsRelationships

Xenofontas Dimitropoulos (Fontas) Xenofontas Dimitropoulos (Fontas) (CAIDA/GaTech)(CAIDA/GaTech)Dmitri KrioukovDmitri Krioukov

Bradley HuffakerBradley Huffakerk claffyk claffy

George RileyGeorge Riley

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OutlineOutline

Background & previous works.Background & previous works. Limitations of existing algorithms.Limitations of existing algorithms. New algorithm to infer customer to New algorithm to infer customer to

provider (c2p) peer to peer (p2p) and provider (c2p) peer to peer (p2p) and sibling to sibling (s2s) relationships.sibling to sibling (s2s) relationships.

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MotivationMotivation Evolution of the Internet.Evolution of the Internet.

– What are the economics of the Internet and their What are the economics of the Internet and their role in shaping it?role in shaping it?

Connectivity doesn’t mean reachability.Connectivity doesn’t mean reachability.– AS relationships determine the valid paths along which AS relationships determine the valid paths along which

packets can flow.packets can flow. Finding a provider or peer for ISPs.Finding a provider or peer for ISPs.

– Details of peering relationships aren’t widely available.Details of peering relationships aren’t widely available.– Want to make a more informed decision based on actual Want to make a more informed decision based on actual

relationships and connectivity instead of “brand name”.relationships and connectivity instead of “brand name”. Determining AS rank.Determining AS rank.

– What is the relative importance of the Internet players?What is the relative importance of the Internet players?– Useful for determining order for security notifications.Useful for determining order for security notifications.

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Valley-free modelValley-free model AS paths have the following hierarchical structure:AS paths have the following hierarchical structure:

1.1. zero or more customer-provider (or sibling) links.zero or more customer-provider (or sibling) links.2.2. zero or one peer-peer link.zero or one peer-peer link.3.3. zero or more provider-customer (or sibling) links.zero or more provider-customer (or sibling) links.

GAO: “On Inferring Autonomous Systems relationships in the GAO: “On Inferring Autonomous Systems relationships in the Internet” Internet”

L. Gao ACM IEEE Transactions on Networking 2001.L. Gao ACM IEEE Transactions on Networking 2001.

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Customer-provider link

Customer-provider links

Peer-peer link

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Previous WorksPrevious Works GAOGAO

– Based on hierarchical property of AS paths.Based on hierarchical property of AS paths.– Use AS degree to find top of the hill and assign Use AS degree to find top of the hill and assign

transit relationships to the side-hill links.transit relationships to the side-hill links. SARKSARK

– Introduce the Type-of-Relationships (ToR) problem:Introduce the Type-of-Relationships (ToR) problem:Given an undirected graph G derived from a set of Given an undirected graph G derived from a set of BGP paths P, assign the edge type (customer-BGP paths P, assign the edge type (customer-provider or peering) to every edge in G such that provider or peering) to every edge in G such that the total number of valid paths in P is maximized.the total number of valid paths in P is maximized.

– Provide a heuristic solution.Provide a heuristic solution.

SARK: “Characterizing the Internet hierarchy from multiple SARK: “Characterizing the Internet hierarchy from multiple vantage points” L. Subramanian et. al INFOCOM 2002.vantage points” L. Subramanian et. al INFOCOM 2002.

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Previous WorksPrevious Works

DPP and EHS:DPP and EHS:– No peering can be inferred in ToR.No peering can be inferred in ToR.– ToR is NP-complete (by reducing to MAX2SAT).ToR is NP-complete (by reducing to MAX2SAT).– Mathematically rigorous approximations to Mathematically rigorous approximations to

ToR.ToR.

DPP: "Computing the types of the relationships between DPP: "Computing the types of the relationships between Autonomous Systems", G. Di Battista et al. IEEE INFOCOM 2003.Autonomous Systems", G. Di Battista et al. IEEE INFOCOM 2003.

EHS: “Classifying customer-provider relationships in the Internet”, EHS: “Classifying customer-provider relationships in the Internet”, T. Erlebach et al. IASTED CCN 2002.T. Erlebach et al. IASTED CCN 2002.

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ToR limitationsToR limitations

ToR does not provide a deterministic ToR does not provide a deterministic solution, because some links can be solution, because some links can be directed either way and produce the same directed either way and produce the same number of valid paths.number of valid paths.

ToR solutions may treat anomalous paths ToR solutions may treat anomalous paths as valid, which results in incorrect as valid, which results in incorrect AS relationships.AS relationships.

– BGP misconfigurations BGP misconfigurations and complex polices can and complex polices can violate the valley freeviolate the valley freemodel.model. 12

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Our customer to provider Our customer to provider algorithmalgorithm

Generate Input:Generate Input:1.1. Produce AS graph (with no relationships).Produce AS graph (with no relationships).

2.2. Assign weight to edges based on node degree.Assign weight to edges based on node degree.

Formulate c2p inference as a multiobjective Formulate c2p inference as a multiobjective optimization problem:optimization problem:

– O1: Maximize number of valid paths.O1: Maximize number of valid paths.– O2: Maximize the sum of weights over all edges.O2: Maximize the sum of weights over all edges.

Intuition:Intuition:– Paths are now colored by their edges weights which Paths are now colored by their edges weights which

allows to detect anomalous paths.allows to detect anomalous paths.

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Valid with small weight Invalid with large weight

W = 0 W > 0

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Work in progressWork in progress

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

relationships.relationships.

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Thanks!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