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Extracting Intra-Domain Topology from mrinfo Probing

Extracting Intra-Domain Topology from mrinfo Probing. JJ Pansiot (Lsiit, UdS) B Donnet, P Mérindol, O Bonaventure (INL, Louvain). Agenda. Background Part 1: mrinfo Context Probing Methodology Dataset Part 2: Delimiting AS Borders Router-2-AS Mapping Evaluation

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Extracting Intra-Domain Topology from mrinfo Probing

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  1. Extracting Intra-Domain Topology from mrinfo Probing JJ Pansiot (Lsiit, UdS) B Donnet, P Mérindol, O Bonaventure (INL, Louvain)

  2. Agenda • Background • Part 1: mrinfo • Context • Probing Methodology • Dataset • Part 2: Delimiting AS Borders • Router-2-AS Mapping • Evaluation • Part 3: Intra-Domain Study • Importance of Layer-2 • Conclusion

  3. Background • Internet graph seen either as • a graph of routers • Constructed for example with traceroute • a graph of domains (AS) • Constructed for example from BGP tables (routeviews) • or both • To study intra-domain graphs • To study interconnection of domains • (our paper at IMC) • need a way to overlay the AS graph on top of the router graph

  4. Part 1: mrinfo • Graph of routers • Usually obtained from traceroute tools • Difficulty to map IP adresses to routers • Aliasing • Need many sources and targets • To increase exhaustivity in edge discovery • Many artifacts • Eg load balancers, changes in routing • => try another way to get information: mrinfo

  5. Probing • Topology discovery using mrinfo • Uses IGMP message • ASK_NEIGHBORS • NEIGHBORS_REPLY • Output • All (multicast) interfaces of a given router • All (multicast) neighbor routers • mrinfo applied recursively • mrinfo-rec

  6. switch Probing

  7. Data set • Four years of data • collected daily • May 1st, 2004 to December 31st, 2008 • Recursive probing scheme: mrinfo-rec • Publicly available • http://svnet.u-strasbg.fr/mrinfo/index.html • (raw data) • http://inl.info.ucl.ac.be/content/mrinfo • (refined data)

  8. Data set: routers

  9. Data set: interfaces

  10. Part 2: Delimiting AS Borders

  11. IP to AS • First step : IP to AS mapping • Obtained from routeviews data • Allows to get a mapping on a given day • Discard some rare cases • Such as MOA (Multiple Origin AS) • Unknown prefixes • AS identified by an ASN (AS Number)

  12. Example routeviews prefix Next Hop AS path * 130.79.0.0 217.75.96.60 0 0 16150 1239 5511 2200 2259 i * 209.161.175.4 0 14608 19029 3356 5511 2200 2259 i * 129.250.0.85 11 0 2914 5511 2200 2259 i * 129.250.0.11 18 0 2914 5511 2200 2259 i * 216.140.8.59 2741 0 6395 5511 2200 2259 i * 216.140.2.59 3800 0 6395 5511 2200 2259 i * 208.186.154.35 0 0 5650 1239 5511 2200 2259 i … * 8.7.83.0/24 217.75.96.60 0 0 16150 6939 5650 12284 32808 32808 i * 209.161.175.4 0 14608 19029 5650 12284 32808 32808 i * 216.140.2.59 0 0 6395 5650 12284 32808 32808 i * 216.140.8.59 20 0 6395 5650 12284 32808 32808 i

  13. Router to AS Mapping • Problem • Graph of routers • Each router has • Many IP addresses (interfaces) • IP => prefix => ASN • IP addresses may belong to different ASes • For each router decide of the « correct » AS

  14. AS2 Or this? Router-2-AS Mapping This?

  15. Router-2-AS Mapping • Idea • Apply a series of rules • At each step a router r • Has an ASN, Asn(r) • An a confidence level c(r), 0 ≤ c(r) ≤ 1 • A rule applied at a given step, if c(r) < 1 • Increase the confidence level • And possibly changes ASN(r) • While remaining consistent with ASN already assigned • Once c(r) = 1, ASN(r) unchanged • => most reliable rules first

  16. Main rule : election elec • The first (main) rule is an election (elec) • router r is given the most frequent AS among its addresses (with tie breaker), ASN1 • Plus a confidence level c(r) • From 1 (all addresses in the same AS) • To 0 (same number of addresses in 2 distinct AS) c(r) = (frequency(ASN1)-frequency(ASN2)) / frequency(ASN1)

  17. Rule loopback lb • If a router has a loopback interface lb • As deduced from the dns name • Eg loop0.ar3.LON2.gblx.net • Then ASN(r) = ASN(lb) with c(r) =1

  18. Rule neighbor N • N rule allows to propagate « ASN certainty » • Assumption • On a P2P link the prefix of the link belongs to the AS of 1 of its end routers • If R1 is in AS1 (with c(R1) = 1) and link R1 - R2 is in AS2 • then ASN(R2) = AS2 with c(R2) =1 • Warning : not applied to multipoint links • Eg IXP

  19. Rule lan • Idea : if router r has an interface to a leaf Lan in ASN (leaf) • Then ASN(r) = ASN(leaf)

  20. Increase confidence and propagate • For remaining routers with 0 < c(r) < 1 • By decreasing order of c(r) • set c(r) to 1 • Propagate to neighbors (rule N)

  21. AS1 AS2 R1 R3 R2 AS1 AS1 AS2 C(R3)=0 AS2 customer of AS1 Rule c2p • Customer to provider rule c2p • Assumption: the link between a provider AS and its customer AS is usually taken in the provider address space • Need to know the AS relationship • Obtained from work by Caida => ASN(R3) = AS2 AS2 C(R3) = 1

  22. Evaluation • Subset of original dataset • 1 probing dataset/month • 56 samples • Purpose • Algorithm efficiency

  23. The power of election

  24. 90% solved after elec 95% solved after lan 0.45% unsolved at the end Other rules : refinement

  25. Closer look at steps

  26. Part 3: Preliminary topology analysis: Some results

  27. Global switch/router ratio

  28. AS3356 Level3

  29. AS1239 Sprint

  30. Les CRS ne répondent plus

  31. Conclusion • New tool for collecting topological data • mrinfo-rec • Intra-Domain topology delimitation • Importance of layer-2

  32. Conclusion • Jean-Jacques Pansiot, Pascal Mérindol, Benoit Donnet, Olivier Bonaventure.Extracting Intra-Domain Topology frommrinfoProbing. In Proc. PAM 2010, Zurich. • Pascal Mérindol, Virginie Van den Schrieck, Benoit Donnet, Olivier Bonaventure, Jean-Jacques Pansiot. Quantifying ASes Multiconnectivity using Multicast Information. In Proc. IMC 2009. • Preliminary analysis: • Jean-Jacques Pansiot. Local and Dynamic Analysis of Internet Multicast Router Topology. Annals of telecommunications, 2007. • Data publicly available • http://svnet.u-strasbg.fr/mrinfo/index.html (raw data) • http://inl.info.ucl.ac.be/content/mrinfo (refined data)

  33. Output of mrinfo 128.103.15.25 (bdrgw2-vl-15-core.net.harvard.edu) [version 12.2]: 192.5.66.204 -> 0.0.0.0 (local) [1/0/pim/querier/leaf] 128.103.15.25 -> 128.103.15.23 (hlkgw1-vl-15-core.net.harvard.edu) [1/0/pim] 128.103.15.25 -> 128.103.15.30 (perkgw1-vl-15-core.net.harvard.edu) [1/0/pim] 128.103.15.25 -> 128.103.15.26 (war10gw1-vl-15-core.net.harvard.edu) [1/0/pim] 128.103.15.25 -> 128.103.15.21 (oxgw3-vl-15-core.net.harvard.edu) [1/0/pim] 128.103.15.25 -> 128.103.15.16 (arsgw1-vl-15-core.net.harvard.edu) [1/0/pim] 128.103.15.25 -> 128.103.15.34 (bdrgw1-ge-3-1-core.net.harvard.edu) [1/0/pim] 128.103.15.25 -> 128.103.15.22 (lowgw1-vl-15-core.net.harvard.edu) [1/0/pim] 128.103.15.25 -> 128.103.15.15 (oxgw2-vl-15-core.net.harvard.edu) [1/0/pim] 128.103.15.25 -> 128.103.15.20 (nh175gw1-vl-15-core.net.harvard.edu) [1/0/pim] 128.103.15.25 -> 128.103.15.27 (st8gw1-vl-15-core.net.harvard.edu) [1/0/pim] 128.103.17.25 -> 128.103.17.23 (hlkgw1-vl-17-rcore.net.harvard.edu) [1/0/pim] 128.103.17.25 -> 128.103.17.30 (perkgw1-vl-17-rcore.net.harvard.edu) [1/0/pim] 128.103.17.25 -> 128.103.17.26 (war10gw1-vl-17-rcore.net.harvard.edu) [1/0/pim] 128.103.17.25 -> 128.103.17.21 (oxgw3-vl-17-rcore.net.harvard.edu) [1/0/pim] 128.103.17.25 -> 128.103.17.17 (cftgw1-vl-17-rcore.net.harvard.edu) [1/0/pim] 128.103.17.25 -> 128.103.17.16 (arsgw1-vl-17-rcore.net.harvard.edu) [1/0/pim] 128.103.17.25 -> 128.103.17.34 (bdrgw1-ge-4-1-rcore.net.harvard.edu) [1/0/pim] 128.103.17.25 -> 128.103.17.27 (st8gw1-vl-17-rcore.net.harvard.edu) [1/0/pim] 128.103.17.25 -> 128.103.17.22 (lowgw1-vl-17-rcore.net.harvard.edu) [1/0/pim] 128.103.17.25 -> 128.103.17.20 (nh175gw1-vl-17-rcore.net.harvard.edu) [1/0/pim] 128.103.252.145 -> 128.103.252.146 (lmagw1-vl-100-core.net.harvard.edu) [1/0/pim] 192.5.89.6 -> 192.5.89.5 (ATM10-400-OC12-GIGAPOPNE.nox.org) [1/0/pim/querier]

  34. After processing ID7 ROUTEUR 128.103.15.25, AS1742 INTER bdrgw2-vl-15-core.net.harvard.edu LOCAL 192.5.66.204(AS1742) -> 0.0.0.0 SWITCH 128.103.15.25(AS1742) -> (AS1742) ID10001 AS1742 ( bdrgw2-vl-15-core.net.harvard.edu -> ) SWITCH 128.103.17.25(AS1742) -> (AS1742) ID9656 AS1742 ( bdrgw2-vl-17-rcore.net.harvard.edu -> ) GLOBAL 128.103.252.145(AS1742) -> 128.103.252.146 (AS1742) ID13 AS1742 ( bdrgw2-vl-100-core.net.harvard.edu -> lmagw1-vl-100-core.net.harvard.edu) GLOBAL 192.5.89.6(AS10578) -> 192.5.89.5 (AS10578) ID3827 AS10578 ( HARVARD-GIGAPOPNE.nox.org -> ATM10-400-OC12-GIGAPOPNE.nox.org) ID10001 SWITCH 128.103.15.0/26, AS1742 INTRA () -> 128.103.15.16 (AS1742) ID1 AS1742 ( -> arsgw1-vl-15-core.net.harvard.edu) () -> 128.103.15.21 (AS1742) ID4 AS1742 ( -> oxgw3-vl-15-core.net.harvard.edu) () -> 128.103.15.20 (AS1742) ID3 AS1742 ( -> nh175gw1-vl-15-core.net.harvard.edu) () -> 128.103.15.30 (AS1742) ID10 AS1742 ( -> perkgw1-vl-15-core.net.harvard.edu) () -> 128.103.15.25 (AS1742) ID7 AS1742 ( -> bdrgw2-vl-15-core.net.harvard.edu) () -> 128.103.15.34 (AS1742) ID11 AS1742 ( -> bdrgw1-ge-3-1-core.net.harvard.edu) () -> 128.103.15.23 (AS1742) ID6 AS1742 ( -> hlkgw1-vl-15-core.net.harvard.edu) () -> 128.103.15.27 (AS1742) ID9 AS1742 ( -> st8gw1-vl-15-core.net.harvard.edu) () -> 128.103.15.15 (AS1742) ID0 AS1742 ( -> oxgw2-vl-15-core.net.harvard.edu) () -> 128.103.15.22 (AS1742) ID5 AS1742 ( -> lowgw1-vl-15-core.net.harvard.edu) () -> 128.103.15.26 (AS1742) ID8 AS1742 ( -> war10gw1-vl-15-core.net.harvard.edu)

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