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Sensibility analysis of BGP convergence and scalability using network simulation. Wolfgang Mühlbauer 5. Oktober 2004. Outline. Running the experiments Influence of MRAI timer settings on convergence times number of updates Propagation of updates number of affected ASes
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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
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
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
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
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
Experiments – Sample topologies Middle Topology SEP: Sensibility analysis of BGP convergence and scalability using network simulation
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
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
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
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
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
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
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
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
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
MRAI – Results SEP: Sensibility analysis of BGP convergence and scalability using network simulation
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
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
MRAI – per-prefix vs per-peer SEP: Sensibility analysis of BGP convergence and scalability using network simulation
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
Propagation – Update Radius radius 0 radius 0 SEP: Sensibility analysis of BGP convergence and scalability using network simulation
Propagation – Update Radius radius 1 radius 1 radius 1 radius 1 radius 1 SEP: Sensibility analysis of BGP convergence and scalability using network simulation
Propagation – Update Radius radius 2 radius 2 SEP: Sensibility analysis of BGP convergence and scalability using network simulation
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
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
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
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
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
Propagation – Affected ASes SEP: Sensibility analysis of BGP convergence and scalability using network simulation
Propagation – Affected ASes Topology 7774 SEP: Sensibility analysis of BGP convergence and scalability using network simulation
Propagation - Radius SEP: Sensibility analysis of BGP convergence and scalability using network simulation
Danke fürs Zuhören! Email: muehlbaw@in.tum.de SEP: Sensibility analysis of BGP convergence and scalability using network simulation