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ecs298k: BGP Routing Protocol lecture #3

ecs298k: BGP Routing Protocol lecture #3. Dr. S. Felix Wu Computer Science Department University of California, Davis http://www.cs.ucdavis.edu/~wu/ wu@cs.ucdavis.edu. CIDR. Longest Matching Rule CIDR (Classless Inter-domain Routing) IP address + Net Mask Length

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ecs298k: BGP Routing Protocol lecture #3

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  1. ecs298k:BGP Routing Protocollecture #3 Dr. S. Felix Wu Computer Science Department University of California, Davis http://www.cs.ucdavis.edu/~wu/ wu@cs.ucdavis.edu ecs289k, spring 2001

  2. CIDR • Longest Matching Rule • CIDR (Classless Inter-domain Routing) • IP address + Net Mask Length • 128.32.12/24 versus 128.32.12/22 • 10000000.00100000.00001100.-------- • 11111111.11111111.11111111.00000000 • 11111111.11111111.11111100.00000000 • Aggregation: • 128.32.12.0/24, 128.32.13.0/24 => 128.32.12.0/23 • 128.32.12.0/23, 128.32.14.0/23 => 128.32.12.0/22 ecs289k, spring 2001

  3. BGP Messages • OPEN • NOTIFICATION • UPDATE (NEW and WITHDRAW) ecs289k, spring 2001

  4. AS Path IP address prefix AS Number Path E E.B.A B.A F B B.A G.B.A A A F.E.B.A A 130.20.0/24 C A How to reach 130.20.5/24 ?? C.A ecs289k, spring 2001

  5. Aggregation B B.A G A A G F 130.20.0/24 C 130.20.0/23 F.G C 130.20.1/24 How to reach 130.20.1/24 ?? ecs289k, spring 2001

  6. Fairness A B A B.A G F G 130.20.1/24 F.G C 130.20.0/23 130.20.0/24 C How to reach 130.20.0/24 ?? D 130.20.0/24 D.C C 130.20.0/24 ecs289k, spring 2001

  7. Multi-Exit-Discriminator 130.20.1/24 A B D 10 Boston 130.20.1/24 C 50 Atlanta 130.20.0/24 ecs289k, spring 2001

  8. Routing Policy • Policy-Based Routing • Aggregation • Forwarding • BGP Updates • IRR (Internet Routing Registry) • Collection of Routing Policy/Objects • RPSL (Routing Policy Specification Language) • a “whois” service to query ecs289k, spring 2001

  9. RPSL (rfc 2622 & 2650) • RPSL objects: • maintainer objects (mntner), autonomous system number objects (aut-num), route objects (route), set objects (as-set, route-set)….. • Route object: • address prefix • % whois -h whois.ra.net 128.223.0.0/16 Route: 128.223.0.0/16 descr: UONet descr: University of Oregon descr: Computing Center descr: Eugene, OR 97403-1212 descr: USA descr: AS3582 mnt-by: MAINT-AS3582 changed: meyer@ns.uoregon.edu 19960222 source: RADB ecs289k, spring 2001

  10. Common Peering Policies Aut-num: AS2 as-name: CAT-NET descr: Catatonic State University import: from AS1 accept ANY import: from AS3 accept <^AS3+$> export: to AS3 announce ANY export: to AS1 announce AS2 AS3 admin-c: AO36-RIPE tech-c: CO19-RIPE mnt-by: OPS4-RIPE changed: orange@ripe.net source: RIPE ecs289k, spring 2001

  11. AS Path Manipulation: G F G.C F.G.C T3 C 130.20.0/24 C How to reach 130.20.0/24 ?? D 130.20.0/24 T1 D.C C 130.20.0/24 C.C.C.C D.C.C.C.C ecs289k, spring 2001

  12. Aggregation Policy Objects aggr-bndry, aggr-mtd, export-comps, inject, holes route: 128.8.0.0/15 origin: AS1 components: <^AS2> route: 128.8.0.0/15 origin: AS1 components: protocol BGP4 {128.8.0.0/16^+} protocol OSPF {128.9.0.0/16^+} route: 128.8.0.0/15 origin: AS1 components: {128.8.0.0/15^-} aggr-mtd: outbound AS-ANY export-comps: {128.8.8.0/24} route: 128.8.0.0/15 origin: AS1 components: {128.8.0.0/15^-} aggr-mtd: outbound AS-ANY inject: upon HAVE-COMPONENTS {128.8.0.0/16, 128.9.0.0/16} holes: 128.8.8.0/24 ecs289k, spring 2001

  13. I-BGP/E-BGP A B C B.A ?? A B.B.A ecs289k, spring 2001

  14. How to prevent loop in... • E-BGP: • examine the AS Path. • As long as we do not find the same AS# twice • I-BGP: • prefix learned from an I-BGP neighbor can NOT be advertized to another I-BGP neighbor. • Full mesh ecs289k, spring 2001

  15. R AS2 AS3 AS0 AS1 BGP Convergence Example *B R via 3 B R via 13 B R via 23 AS0 *B R via 3 B R via 03 B R via 23 AS1 *B R via 3 B R via 03 B R via 13 AS2 ecs289k, spring 2001

  16. 36% Average: 110 (min/max 78/135) seconds Announce AS4 AS5 AS (52 seconds) Withdraw (110 seconds) 35% Average: 107 (min/max 91/133) seconds Announce AS4 AS1 AS3 (39 seconds) Announce AS4 AS5 AS3 (68 seconds) Withdraw (107 seconds) 2% Average:140.00 (min/max 120/142) Announce AS4 AS5 AS8 AS7 AS3 (27) Announce AS4 AS5AS9 AS8 AS7 AS3 (86) Withdraw (140 seconds) 27% Other P6 P5 P4 ISP 9 P2 P5 P3 ISP 5 P5 P7 P6 ISP 8 P7 ISP 1 P2 P5 P4 P6 P7 P3 P5 ISP 7 P4 P6 P7 ISP3-ISP4 Paths During Failure ISP 4 Steady State FAULT R3 ISP 3 ecs289k, spring 2001

  17. 63% Average: 79 (min/max 44/208) seconds AS4 AS5 AS2 (35 seconds) Withdraw (79 seconds) 7% Average: 88 (min/max 80/94) seconds Announce AS4 AS5 AS2 (33 seconds) Announce AS4 AS6 AS5 AS2 (61 seconds) Withdraw (88 seconds) 7% Average: 54 (min/max 29/9) seconds Withdraw (54 seconds) 23% Other P4 P3 ISP 13 P4 P2 ISP 6 ISP 12 P3 P4 Vagabond ISP 5 ISP 11 P2 P4 P3 ISP 10 P4 ISP2-ISP4 Paths During Failure ISP 4 Steady State FAULT R2 ISP 2 ecs289k, spring 2001

  18. P2 ISP 5 96% Average: 92 (min/max 63/140) seconds Announce AS4 AS5 AS1 (44 seconds) Withdraw (92 seconds) 4% Average: 32 (min/max 27/38) seconds Withdraw (32 seconds) P2 ISP1-ISP4 Paths During Failure ISP 4 • Only one back up path (length 3) Steady State FAULT R1 ISP 1 ecs289k, spring 2001

  19. Remarks • Try it please…. ecs289k, spring 2001

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