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Experiential analysis of Internet AS-level structure Yangyang Wang advisor: Prof. Jianping Wu NCR, Tsinghua University.

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Presentation on theme: "Experiential analysis of Internet AS-level structure Yangyang Wang advisor: Prof. Jianping Wu NCR, Tsinghua University."— Presentation transcript:

1 Experiential analysis of Internet AS-level structure Yangyang Wang advisor: Prof. Jianping Wu NCR, Tsinghua University

2 outlines Motivation Related work analysis methods Data source Some results Conclusion

3 motivation ASes are the basic units of Internet Internet AS-level topology research can help: – Internet topology modeling – Network design planning – architecture design or optimizing for wide-area distributed system

4 Related work Some related work (not all) – Jellyfish conceptual model (G. Siganos, JCN 2006) Undirected graph Degree-based – BGP routing table tomography from Multiple Vantage Points (L. Subramanian INFOCOM02) Directed graph derived from AS_PATH from BGP monitor

5 methods Topology with AS relationship is a directed graph G – Each vertex is AS – directed edge: connection between ASes – customer-provider, peer-peer, sibling-sibling Provider Customer one directed edge represent a C2P relationship Peer/ Sibling Peer/ Sibling P2P or S2S relationship is split into two inverse directed edges

6 methods Ranking algorithms r = 1 while (leaves(G) is not empty) { for each v of leaves(G) rank(v) = R; remove leaves from G, get a new G; r = r + 1; } for all the rest v in G rank(v) = r; Case 1: Leaves(G) are vertexes without customers. It just considers the C2P hierarchy, ignore P2P and S2S. Case 2: Leaves(G) are vertexes without customers, peers and siblings.

7 Data source CAIDA inferred AS relationship dataset – – Its raw data are from RouteViews project and IRR(Internet Routing Registry) Data in 03/03/ /17/2008 – as-rel a txt as-rel a txt as-rel a txt – Joined them into one data file, choose the inferred relationship with higher occurrence frequency as the final relationship for each link

8 layers hierarchical layers of Case (87%) 2468 (9%) 584 (2%) 176 (1%) 202 (1%) Outmost layer with very high number of AS These middle layers include very little number of AS Innermost layer

9 layers hierarchical layers of Case (85%) 2014 (7%) 308 (1%) (7%) bigger Innermost layer than Case 1 Less layers than Case 1 Outmost layer with very high number of AS

10 Other metrics We can examine other aspects: – the number of links in each layer itself – the number of cross links and included P2P links from one layer to the other layers – average degree of the rest graph G after removing layer n – link connection density of the rest graph G after removing layer n, and defined as (E(G)* 2) / (V(G)* (V(G) – 1))

11 other metrics layer (core)p2p link(to core) average degree links density (85.1%) (89.9%) (89.5%) (87.1%) (90.7%) (97.7%) (97.6%) (97.0%) (88.9%) (100%) (100%) cross layer links table of Case 1 many of cross links few of cross links plenty of cross links approximate increasing

12 other metrics layer (core)p2p link (to core) average degree links density (100%) (100%) (100%) (100%) (100%) cross layer links table of Case 2 many of cross links few of cross links plenty of cross links

13 degrees vs. layer rank Case 2 Case 1 we could see that vertexes with high degree may be in lower hierarchy rank

14 conclusion conceptual conclusions – there are a small core (less than 10%), large margin AS (more than 80%), and middle AS band (about 10%) – remove margin AS, the rest network size is not very small (about 10%) and connections are very complex – although outer AS have most connections to the core, there are a few connections to middle AS zone, which reduce the regional routing path.

15 Problems and future work Problems: – inaccurate AS relationship Missing P2P links – incomplete topology data Limited BGP monitor Measurement bias Future work – other method of charactering structure pattern – Whats the size of the core as Internet expands – What would look like the topology structure in the future years according current principles

16 Thanks !


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