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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 - PowerPoint PPT Presentation
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SEP: Sensibility analysis of BGP convergence and scalability using network simulation
Sensibility analysis of Sensibility analysis of BGP convergence and BGP convergence and scalability using scalability using network simulationnetwork simulation
Sensibility analysis of Sensibility analysis of BGP convergence and BGP convergence and scalability using scalability using network simulationnetwork simulation
Wolfgang Mühlbauer
5. Oktober 2004
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
OutlineOutlineOutlineOutline
• 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 - SSFNetExperiments - SSFNetExperiments - SSFNetExperiments - 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 Experiments – Doing simulationsimulation
Experiments – Doing Experiments – Doing simulationsimulation
• 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
Subtree (AS Pairs)
AS Pairs DML FilesSimulation
SSFNet
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
Experiments – DML FilesExperiments – DML FilesExperiments – DML FilesExperiments – 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 Experiments – Sample topologiestopologies
Experiments – Sample Experiments – Sample topologiestopologies
# ASes # external links
based on AS Pairs?
Middle Topology 15 27 no
Topology 1140 95 1145 yes (2003)
Topology 7774 105 614 yes (04/2004)
Middle Topology
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
OutlineOutlineOutlineOutline
• 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 worksMRAI – How it worksMRAI – How it worksMRAI – How it works
AS 3
AS 1AS 2
AS 4
AS 5
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
MRAI – How it worksMRAI – How it worksMRAI – How it worksMRAI – How it works
AS 3
AS 1AS 2
AS 4
AS 5
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 worksMRAI – How it worksMRAI – How it worksMRAI – How it works
AS 3
AS 1AS 2
AS 4
AS 5
AS 2 "passes on" the information to AS 4
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
MRAI – How it worksMRAI – How it worksMRAI – How it worksMRAI – How it works
AS 3
AS 1AS 2
AS 4
AS 5
AS 4 "passes on" the information to AS 5
timer instance is started
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
MRAI – How it worksMRAI – How it worksMRAI – How it worksMRAI – How it works
AS 3
AS 1AS 2
AS 4
AS 5
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 worksMRAI – How it worksMRAI – How it worksMRAI – How it works
AS 3
AS 1AS 2
AS 4
AS 5
AS 4 may prefer to reach AS 1 via AS 3, but …
timer is not expired yet
?
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
MRAI – How it worksMRAI – How it worksMRAI – How it worksMRAI – How it works
AS 3
AS 1AS 2
AS 4
AS 5
update is sent, now AS 4 can reach AS 1 via AS 3
timer expires
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
MRAI – SimulationsMRAI – SimulationsMRAI – SimulationsMRAI – Simulations
• Automatical testing of 3 dimensions:
• For Topology 7774 measure:– Convergence time– Number of external updates
different link failures (5)
MRAI timer values in sec (4,5,10,...,60)
different seeds (20)
simulation
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
MRAI – ResultsMRAI – ResultsMRAI – ResultsMRAI – Results
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
MRAI – per prefix or per MRAI – per prefix or per peerpeer
MRAI – per prefix or per MRAI – per prefix or per peerpeer
per peer per prefix
0.0.0.1/26
0.0.0.2/26
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
MRAI – per prefix or per MRAI – per prefix or per peerpeer
MRAI – per prefix or per MRAI – per prefix or per peerpeer
• 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-MRAI – per-prefix vs per-peerpeer
MRAI – per-prefix vs per-MRAI – per-prefix vs per-peerpeer
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
OutlineOutlineOutlineOutline
• 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 Propagation – Update RadiusRadius
Propagation – Update Propagation – Update RadiusRadius
radius 0
radius 0
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
Propagation – Update Propagation – Update RadiusRadius
Propagation – Update Propagation – Update RadiusRadius
radius 1
radius 1
radius 1
radius 1radius 1
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
Propagation – Update Propagation – Update RadiusRadius
Propagation – Update Propagation – Update RadiusRadius
radius 2
radius 2
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
Propagation – Affected Propagation – Affected ASesASes
Propagation – Affected Propagation – Affected ASesASes
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 Propagation – Affected ASesASes
Propagation – Affected Propagation – Affected ASesASes
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 Propagation – Affected ASesASes
Propagation – Affected Propagation – Affected ASesASes
US to D2) D to US
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 Propagation – Link ClassificationClassification
Propagation – Link Propagation – Link ClassificationClassification
• 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 - Propagation - SimulationsSimulations
Propagation - Propagation - SimulationsSimulations
• 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 Propagation – Affected ASesASes
Propagation – Affected Propagation – Affected ASesASes
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
Propagation – Affected Propagation – Affected ASesASes
Propagation – Affected Propagation – Affected ASesASesTopology 7774
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
Propagation - RadiusPropagation - RadiusPropagation - RadiusPropagation - Radius
SEP: Sensibility analysis of BGP convergence and scalability using network simulation
Danke fürs Zuhören!Danke fürs Zuhören!Danke fürs Zuhören!Danke fürs Zuhören!
Email: [email protected]