1. 04/10/2001ecs289k, spring 20011 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

2. 04/10/2001ecs289k, spring 20012 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

3. 04/10/2001ecs289k, spring 20013 BGP Messages OPEN NOTIFICATION UPDATE (NEW and WITHDRAW)

4. 04/10/2001ecs289k, spring 20014 AS Path A B C E F A 130.20.0/24 A A B.A E.B.A G.B.A F.E.B.A C.A How to reach 130.20.5/24 ?? IP address prefix AS Number Path

5. 04/10/2001ecs289k, spring 20015 Aggregation A B G F A 130.20.0/24 B.A G F.G C How to reach 130.20.1/24 ?? C 130.20.1/24 130.20.0/23

6. 04/10/2001ecs289k, spring 20016 Fairness AB GF A 130.20.1/24 B.A G F.G C How to reach 130.20.0/24 ?? C 130.20.0/24 130.20.0/23 130.20.0/24 D C D.C 130.20.0/24

7. 04/10/2001ecs289k, spring 20017 Multi-Exit-Discriminator A 130.20.1/24 C 130.20.0/24 BD Boston Atlanta 10 50 130.20.1/24

8. 04/10/2001ecs289k, spring 20018 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

9. 04/10/2001ecs289k, spring 20019 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

10. 04/10/2001ecs289k, spring 200110 Common Peering Policies Aut-num:AS2 as-name:CAT-NET descr:Catatonic State University import:from AS1 accept ANY import:from AS3 accept 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

11. 04/10/2001ecs289k, spring 200111 AS Path Manipulation: GF G.C F.G.C C How to reach 130.20.0/24 ?? C 130.20.0/24 D C D.C 130.20.0/24 T3 T1 C.C.C.CD.C.C.C.C

12. 04/10/2001ecs289k, spring 200112 Aggregation Policy Objects aggr-bndry, aggr-mtd, export-comps, inject, holes route:128.8.0.0/15 origin:AS1 components: 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

13. 04/10/2001ecs289k, spring 200113 I-BGP/E-BGP AB A B.A C B.B.A ??

14. 04/10/2001ecs289k, spring 200114 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

15. 04/10/2001ecs289k, spring 200115 BGP Convergence Example R AS0 AS1 AS2 AS3 *B Rvia 3 B R via 03 B R via 23 *B Rvia 3 B R via 03 B R via 13 *B Rvia 3 B R via 13 B R via 23 AS0AS1AS2

16. 04/10/2001ecs289k, spring 200116 ISP3-ISP4 Paths During Failure ISP 3 Steady State ISP 4 R3R3 P2 ISP 5 FAULT ISP 1 P3 P6 P7 P4 P5 P6 ISP 7 ISP 9 ISP 8 P7 P4 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

17. 04/10/2001ecs289k, spring 200117 ISP2-ISP4 Paths During Failure Steady State ISP 2 ISP 4 P2 ISP 5 P3 ISP 6 R2R2 FAULT Vagabond P4 ISP 10 ISP 11 ISP 12 ISP 13 P4 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

18. 04/10/2001ecs289k, spring 200118 ISP1-ISP4 Paths During Failure Only one back up path (length 3) Steady State ISP 1 ISP 5 P2 ISP 4 R1R1 FAULT 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)

19. 04/10/2001ecs289k, spring 200119 Remarks Try it please….