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Sensibility Analysis of BGP Convergence and Scalability

Explore BGP convergence and scalability using network simulations. Experiments, MRAI timer influence, sample topologies & results discussed.

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Sensibility Analysis of BGP Convergence and Scalability

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  1. Sensibility analysis of BGP convergence and scalability using network simulation Wolfgang Mühlbauer 5. Oktober 2004 SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  2. Outline • Running the experiments • Influence of MRAI timer settings on • convergence times • number of updates • Propagation of updates • number of affected ASes • propagation radius SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  3. Experiments - SSFNet • Network simulation with SSFNet • global view • existing BGP implementation • Modifications to SSFNet • Modeling the behavior of Cisco routers • Normal distribution of MRAI timer value • Community values • Best Path Selection Process, … • Configuring link failures • MRAI timer basis: per-peer or per-prefix, … SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  4. Experiments – Doing simulation • AS Pairs: define topology, reflect commercial relationships (e.g. 12>13) • Subtree extraction: reduce complexity and size of sample networks • DML Files: configuration files, input for SSFNet AS Pairs Subtree (AS Pairs) DML Files SimulationSSFNet SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  5. Experiments – DML Files • Topology Converter: Automatical generation of DML files out of AS Pairs • Configurable BGP parameters: • MRAI timer • Link failure dynamics • Interior structure of ASes (route reflectors, …) • WRATE, SSLD • … SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  6. Experiments – Sample topologies Middle Topology SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  7. Outline • Running the experiments • Influence of MRAI timer settings on • convergence times • number of updates • Propagation of updates • number of affected Ases • propagation radius SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  8. MRAI – How it works AS 2 AS 1 AS 5 AS 3 AS 4 SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  9. MRAI – How it works AS 2 AS 1 AS 5 AS 3 AS 4 AS 1 issues an update to AS 2 and AS 3 SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  10. MRAI – How it works AS 2 AS 1 AS 5 AS 3 AS 4 AS 2 "passes on" the information to AS 4 SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  11. timer instance is started MRAI – How it works AS 2 AS 1 AS 5 AS 3 AS 4 AS 4 "passes on" the information to AS 5 SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  12. MRAI – How it works AS 2 AS 1 AS 5 AS 3 AS 4 AS 3 sends its update to AS 4 not until now! SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  13. MRAI – How it works AS 2 AS 1 ? AS 5 timer is not expired yet AS 3 AS 4 AS 4 may prefer to reach AS 1 via AS 3, but … SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  14. MRAI – How it works AS 2 AS 1 AS 5 timer expires AS 3 AS 4 update is sent, now AS 4 can reach AS 1 via AS 3 SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  15. different link failures (5) MRAI timer values in sec (4,5,10,...,60) different seeds (20) simulation MRAI – Simulations • Automatical testing of 3 dimensions: • For Topology 7774 measure: • Convergence time • Number of external updates SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  16. MRAI – Results SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  17. 0.0.0.1/26 0.0.0.2/26 MRAI – per prefix or per peer per peer per prefix SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  18. MRAI – per prefix or per peer • used topologies: • Topology 1140 • Topology 7774 • testing of 4 dimensions • 5 different failure scenarios • different MRAI timer values (4s, 5s, 10s, …, 60s) • per-peer and per-prefix timer basis • 3 different seeds for random number generator • we measure • convergence times • number of external updates SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  19. MRAI – per-prefix vs per-peer SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  20. Outline • Running the experiments • Influence of MRAI timer settings on • convergence times • number of updates • Propagation of updates • number of affected Ases • propagation radius SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  21. Propagation – Update Radius radius 0 radius 0 SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  22. Propagation – Update Radius radius 1 radius 1 radius 1 radius 1 radius 1 SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  23. Propagation – Update Radius radius 2 radius 2 SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  24. Propagation – Affected ASes 1) US to D 2) D to US US providers use link 1 for German destinations German providers use link 2 for US destinations SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  25. Propagation – Affected ASes 1) US to D 2) D to US Link 1 fails due to some reason SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  26. Propagation – Affected ASes 2) D to US US to D Even traffic from US to D is now routed over link 2 But: Routers in D won‘t get an update message and are therefore not „affected“ SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  27. Propagation – Link Classification • classify ASes according to their commercial relationships: • tier1 ASes: no provider • stub ASes: no customer • middle Ases: all the rest • classify external links according to the ASes they connect: tier1-tier1, tier1-middle, middle-middle, middle-stub, stub-stub • Harmfulness of links reflected? SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  28. Propagation - Simulations • used topologies: • Topology Middle • Topology 1140 • Topology 7774 • testing of 3 dimensions • 10 different failure scenarios • different link categories • 3 different seeds for random number generator • we measure • number and ratio of affected ASes • mean and maximum of propagation radius SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  29. Propagation – Affected ASes SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  30. Propagation – Affected ASes Topology 7774 SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  31. Propagation - Radius SEP: Sensibility analysis of BGP convergence and scalability using network simulation

  32. Danke fürs Zuhören! Email: muehlbaw@in.tum.de SEP: Sensibility analysis of BGP convergence and scalability using network simulation

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