SEP: Sensibility analysis of BGP convergence and scalability using network simulation 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 OutlineOutline 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 Subtree (AS Pairs) AS PairsDML Files Simulatio nSSFNet

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 # ASes# external links based on AS Pairs? Middle Topology1527no Topology yes (2003) Topology yes (04/2004) Middle Topology

SEP: Sensibility analysis of BGP convergence and scalability using network simulation OutlineOutline 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 3 AS 1 AS 2 AS 4 AS 5

SEP: Sensibility analysis of BGP convergence and scalability using network simulation MRAI – How it works AS 3 AS 1 AS 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 works AS 3 AS 1 AS 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 works AS 3 AS 1 AS 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 works AS 3 AS 1 AS 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 works AS 3 AS 1 AS 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 works AS 3 AS 1 AS 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 – 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 – Results

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

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 OutlineOutline 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

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

SEP: Sensibility analysis of BGP convergence and scalability using network simulation Propagation – Update Radius 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 US to D 2) 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 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!