Routing Protocol RIP 19 2 kbps T 1

Routing Protocol (RIP) 19. 2 kbps T 1 T 1 • Hop count metric

Distance Vector—Selecting Best Route with Metrics EIGRP A Bandwidth 56 Delay RIP Hop count Load T 1 56 Reliability OSPF Cost (Bandwidth) MTU T 1 B Information used to select the best path for routing © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -4

Distance Vector Routing Protocols B A C Distance—How far Vector—In which direction D D C B A Routing Table - Distance Vector Routing Protocol은 Neighbor Router 에게 주기적 으로 Routing Table을 Update. ( RIP 30초, IGRP 90초) © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -6

Distance Vector—Sources of Information and Discovering Routes 10. 1. 0. 0 E 0 10. 2. 0. 0 A S 0 Routing Table 10. 3. 0. 0 B S 0 S 1 Routing Table 10. 4. 0. 0 S 0 C E 0 Routing Table 10. 1. 0. 0 E 0 0 10. 2. 0. 0 S 0 0 10. 3. 0. 0 S 1 0 10. 4. 0. 0 E 0 0 Routers discover the best path to destinations from each neighbor © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -7

Distance Vector—Sources of Information and Discovering Routes 10. 1. 0. 0 E 0 10. 2. 0. 0 A S 0 Routing Table 10. 3. 0. 0 B S 0 S 1 Routing Table 10. 4. 0. 0 S 0 C E 0 Routing Table 10. 1. 0. 0 E 0 0 10. 2. 0. 0 S 0 0 10. 3. 0. 0 S 1 0 10. 4. 0. 0 E 0 0 10. 3. 0. 0 S 0 1 10. 4. 0. 0 S 1 1 10. 2. 0. 0 S 0 1 10. 1. 0. 0 S 0 1 Routers discover the best path to destinations from each neighbor © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -8

Distance Vector—Sources of Information and Discovering Routes 10. 1. 0. 0 E 0 10. 2. 0. 0 A S 0 Routing Table 10. 3. 0. 0 B S 0 S 1 Routing Table 10. 4. 0. 0 S 0 C E 0 Routing Table 10. 1. 0. 0 E 0 0 10. 2. 0. 0 S 0 0 10. 3. 0. 0 S 1 0 10. 4. 0. 0 E 0 0 10. 3. 0. 0 S 0 1 10. 4. 0. 0 S 1 1 10. 2. 0. 0 S 0 1 10. 4. 0. 0 S 0 2 10. 1. 0. 0 S 0 1 10. 1. 0. 0 S 0 2 Routers discover the best path to destinations from each neighbor © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -9

Maintaining Routing Information Problem—Routing Loops Convergence (수렴) Time - Convergence 네트워크에 변화가 생길 경우 모든 Router가 네트워크 변화 상태에 대한 정확하고 일관된 정보를 유지하는 것. - Convergence Time 네트워크에 변화가 생겼을 경우 그 변화된 정보를 서로 인식하고 수정하는 시간 Convergence Time은 각 Routing Protocol별로 다르다. Convergence Time은 짧을 수록 좋다. - RIP 같은 경우는 Convergence Time이 30초. * RIP 같은 경우는 Convergence Time이 30초로 느리다. 때문에 Routing Loop 문제가 발생한다. © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -10

Maintaining Routing Information Problem—Routing Loops Routing Table © 1999, Cisco Systems, Inc. www. cisco.

Maintaining Routing Information Problem—Routing Loops Router C 의 10. 4. 0. 0 Network 장애발생

Maintaining Routing Information Problem—Routing Loops • Router C 는 10. 4. 0. 0 Network의

Maintaining Routing Information Problem—Routing Loops • Router A 는 Router B 로 부터 잘못된

Maintaining Routing Information Problem—Routing Loops Network 10. 4. 0. 0 의 잘못된 정보가 계속

Maintaining Routing Information Problem—Routing Loops 16 Hop (Hop-Count-Limit) © 1999, Cisco Systems, Inc. www.

Maintaining Routing Information Problem—Routing Loops • Packet 은 10. 4. 0. 0으로 가기 위해서

Maintaining Routing Information Problem—Routing Loops - 해결책 1)Split Horizon 2) Route Poisoning, Poison reverse 3) Hold Down Timer 4) Triggered Update © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -18

Solution: Split Horizon 10. 1. 0. 0 E 0 10. 2. 0. 0 A S 0 Routing Table X 10. 3. 0. 0 S 0 B S 1 Routing Table X 10. 4. 0. 0 S 0 C E 0 X Routing Table 1 1 1 2 2 2 It is never useful to send information about a route back in the direction from which the original packet came © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -19

Solution: Route Poisoning 10. 1. 0. 0 E 0 10. 2. 0. 0 A S 0 Routing Table 10. 3. 0. 0 B S 0 S 1 Routing Table 10. 4. 0. 0 S 0 C E 0 X Routing Table 10. 1. 0. 0 E 0 0 10. 2. 0. 0 S 0 0 10. 3. 0. 0 S 1 0 10. 4. 0. 0 S 0 Infinity 10. 3. 0. 0 S 0 1 10. 4. 0. 0 S 1 1 10. 2. 0. 0 S 0 1 10. 4. 0. 0 S 0 2 10. 1. 0. 0 E 1 2 10. 1. 0. 0 S 0 2 0 Routers set the distance of routes that have gone down to infinity © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -20

Solution: Poison Reverse 10. 1. 0. 0 E 0 10. 2. 0. 0 A S 0 10. 3. 0. 0 B S 0 S 1 10. 4. 0. 0 S 0 C E 0 X Poison Reverse Routing Table 10. 1. 0. 0 E 0 0 10. 2. 0. 0 S 0 0 10. 3. 0. 0 S 1 0 10. 4. 0. 0 S 0 Infinity 10. 3. 0. 0 S 0 1 10. 4. 0. 0 S 1 Possibly Down 10. 2. 0. 0 S 0 1 10. 4. 0. 0 S 0 2 10. 1. 0. 0 E 1 2 10. 1. 0. 0 S 0 2 0 Poison Reverse overrides split horizon © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -21

Solution: Hold-Down Timers Network 10. 4. 0. 0 is unreachable Update after hold-down Time 10. 1. 0. 0 10. 2. 0. 0 E 0 A S 0 10. 3. 0. 0 B Update after hold-down Time S 1 10. 4. 0. 0 S 0 C E 0 X Network 10. 4. 0. 0 is down then back up then back down Router keeps an entry for the network possibly down state, allowing time for other routers to recompute for this topology change © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -22

Solution: Triggered Updates Network 10. 4. 0. 0 is unreachable 10. 1. 0. 0 E 0 Network 10. 4. 0. 0 is unreachable 10. 2. 0. 0 A S 0 10. 3. 0. 0 B S 1 10. 4. 0. 0 S 0 C E 0 X Router sends updates when a change in its routing table occurs © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -23

Implementing Solutions in Multiple Routes D 10. 4. 0. 0 E B X C

Implementing Solutions in Multiple Routes (cont. ) Holddown D 10. 4. 0. 0 E

Implementing Solutions in Multiple Routes (cont. ) Holddown Poison Reverse D Poison Reverse 10. 4. 0. 0 E B X C Holddown Poison Reverse A Holddown © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -27

Implementing Solutions in Multiple Routes (cont. ) D 10. 4. 0. 0 E B

RIP Configuration Router(config)#router rip • Starts the RIP routing process Router(config-router)#network-number • Selects participating attached networks • The network number must be a major classful network number © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -31

RIP Configuration Example E 0 172. 16. 1. 0 S 2 A 172. 16. 1. 1 10. 1. 1. 2 S 3 B S 3 E 0 C 10. 2. 2. 2 10. 2. 2. 3 192. 168. 1. 1 router rip 2. 3. 0. 0 network 172. 16. 0. 0 network 10. 0 192. 168. 1. 0 router rip 2. 3. 0. 0 network 192. 168. 1. 0 network 10. 0 router rip network 10. 0 © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -32

Verifying the Routing Protocol —RIP E 0 172. 16. 1. 0 S 2 A 172. 16. 1. 1 10. 1. 1. 1 S 2 10. 1. 1. 2 S 3 B S 3 E 0 C 10. 2. 2. 2 10. 2. 2. 3 192. 168. 1. 1 192. 168. 1. 0 Router. A#sh ip protocols Routing Protocol is "rip" Sending updates every 30 seconds, next due in 0 seconds Invalid after 180 seconds, hold down 180, flushed after 240 Outgoing update filter list for all interfaces is Incoming update filter list for all interfaces is Redistributing: rip Default version control: send version 1, receive any version Interface Send Recv Key-chain Ethernet 0 1 12 Serial 2 1 12 Routing for Networks: 10. 0 172. 16. 0. 0 Routing Information Sources: Gateway Distance Last Update 10. 1. 1. 2 120 00: 10 Distance: (default is 120) © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -33

Displaying the IP Routing Table E 0 172. 16. 1. 0 S 2 A 172. 16. 1. 1 10. 1. 1. 1 S 2 10. 1. 1. 2 S 3 B S 3 E 0 C 10. 2. 2. 2 10. 2. 2. 3 192. 168. 1. 1 192. 168. 1. 0 Router. A#sh ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N 1 - OSPF NSSA external type 1, N 2 - OSPF NSSA external type 2 E 1 - OSPF external type 1, E 2 - OSPF external type 2, E - EGP i - IS-IS, L 1 - IS-IS level-1, L 2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR T - traffic engineered route Gateway of last resort is not set 172. 16. 0. 0/24 is subnetted, 1 subnets 172. 16. 1. 0 is directly connected, Ethernet 0 10. 0/24 is subnetted, 2 subnets R 10. 2. 2. 0 [120/1] via 10. 1. 1. 2, 00: 07, Serial 2 C 10. 1. 1. 0 is directly connected, Serial 2 R 192. 168. 1. 0/24 [120/2] via 10. 1. 1. 2, 00: 07, Serial 2 C © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -34

debug ip rip Command E 0 172. 16. 1. 0 S 2 A 172. 16. 1. 1 10. 1. 1. 1 S 2 10. 1. 1. 2 S 3 B S 3 E 0 C 10. 2. 2. 2 10. 2. 2. 3 192. 168. 1. 1 192. 168. 1. 0 Router. A#debug ip rip RIP protocol debugging is on Router. A# 00: 06: 24: RIP: received v 1 update from 10. 1. 1. 2 on Serial 2 00: 06: 24: 10. 2. 2. 0 in 1 hops 00: 06: 24: 192. 168. 1. 0 in 2 hops 00: 06: 33: RIP: sending v 1 update to 255 via Ethernet 0 (172. 16. 1. 1) 00: 06: 34: network 10. 0, metric 1 00: 06: 34: network 192. 168. 1. 0, metric 3 00: 06: 34: RIP: sending v 1 update to 255 via Serial 2 (10. 1. 1. 1) 00: 06: 34: network 172. 16. 0. 0, metric 1 © 1999, Cisco Systems, Inc. www. cisco. com ICND— 12 -35