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ecs298k: BGP Routing Protocol (2) lecture #4. Dr. S. Felix Wu Computer Science Department University of California, Davis http://www.cs.ucdavis.edu/~wu/ wu@cs.ucdavis.edu. AS2. BGP Routing and Policy. BGP Routing Policy. RPSL. Aggregation Policy Objects.
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ecs298k:BGP Routing Protocol (2)lecture #4 Dr. S. Felix Wu Computer Science Department University of California, Davis http://www.cs.ucdavis.edu/~wu/ wu@cs.ucdavis.edu ecs289k, spring 2001
AS2 BGP Routing and Policy BGP Routing Policy RPSL ecs289k, spring 2001
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
I-BGP/E-BGP A B C B.A ?? A B.B.A ecs289k, spring 2001
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
Route Flap Dampening If “flap” too frequent, treat it as down…. ecs289k, spring 2001
ISP Example ISP3 - AS3 ISP1 - AS1 ISP2 - AS2 R1 Customer1 AS10 Customer2 AS20 Customer3 AS30 Community attribute: 1:777 1:666 138.39/16 204.70/16 128.4/16 132.151/16 206.1.5/24 ecs289k, spring 2001
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
AS6453 AS2497 N > 4? 6453 1239 5696 237 AS6113 2497 5696 237 6113 2914 237 AS6461 6461 5696 237 AS1239 1239 5696 237 AS5696 5696 237 AS2914 2914 237 AS237 237 AS701 701 6461 5696 237 AS5000 5000 237 AS1 AS1673 1 5696 237 1673 5696 237
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
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
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