1. Interfacing Interior and Exterior Gateway Protocols

2. 2 Two classes of routing protocols Exterior Gateway Protocol (e.g., BGP) –Used to exchange routes between different domains (autonomous systems) Interior Gateway Protocol (e.g., IS-IS, OSPF, RIP, IGRP) –Used to establish routing tables within a domain

3. Redistribution of OSPF routes into BGP 3 http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800943c5.shtml hostname RTB ! interface Ethernet0/0 ip address 2.2.2.3 255.255.255.0 ! interface Serial1/0 ip address 3.3.3.1 255.0.0.0 ! router ospf 1 network 2.0.0.0 0.255.255.255 area 1 ! router bgp 100 redistribute ospf 1 match internal external 1 external 2 neighbor 3.3.3.2 remote-as 200 ! End

4. Redistribution of OSPF routes into BGP 4 http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800943c5.shtml RTB# show ip route 2.0.0.0/24 is subnetted, 1 subnets C 2.2.2.0 is directly connected, Ethernet0/0 C 3.0.0.0/8 is directly connected, Serial1/0 O E2 200.1.1.0/24 [110/20] via 2.2.2.2, 00:16:17, Ethernet0/0 O E1 200.2.2.0/24 [110/104] via 2.2.2.2, 00:00:41, Ethernet0/0 131.108.0.0/24 is subnetted, 2 subnets O 131.108.2.0 [110/74] via 2.2.2.2, 00:16:17, Ethernet0/0 O IA 131.108.1.0 [110/84] via 2.2.2.2, 00:16:17, Ethernet0/0 Codes: C – connected O – OSPF E1 – OSPF external type 1 E2 – OSPF external type 2 IA – Inter-area

5. Redistribution of OSPF routes into BGP 5 http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800943c5.shtml RTB# show ip bgp BGP table version is 30, local router ID is 192.168.1.7 NetworkNext HopMetric LocPrfWeightPath *> 2.2.2.0/24 0.0.0.0032768? *> 131.108.1.0/242.2.2.28432768? *> 131.108.2.0/242.2.2.27432768? *> 200.1.1.02.2.2.22032768? *> 200.2.2.02.2.2.210432768? Key: * - valid > - best route

6. Redistribution of OSPF routes into BGP 6 http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800943c5.shtml RTC# sh ip route 2.0.0.0/24 is subnetted, 1 subnets B 2.2.2.0 [20/0] via 3.3.3.1, 00:01:24 C 3.0.0.0/8 is directly connected, Serial0/0 B 200.1.1.0/24 [20/20] via 3.3.3.1, 00:01:24 B 200.2.2.0/24 [20/104] via 3.3.3.1, 00:01:24 131.108.0.0/24 is subnetted, 2 subnets B 131.108.2.0 [20/74] via 3.3.3.1, 00:01:24 B 131.108.1.0 [20/84] via 3.3.3.1, 00:01:24

7. Redistribution of BGP routes into OSPF Router R1 interface Loopback0 ip address 1.1.1.1 255.255.255.255 ! interface Loopback1 ip address 172.16.1.1 255.255.0.0 ! interface Serial1/0 ip address 192.12.12.1 255.255.255.0 serial restart-delay 0 ! router bgp 100 no synchronization bgp router-id 1.1.1.1 bgp log-neighbor-changes network 1.1.1.1 mask 255.255.255.255 network 172.16.0.0 neighbor 192.12.12.2 remote-as 100 no auto-summary Router R2 interface Loopback0 ip address 2.2.2.2 255.255.255.255 ! interface Serial1/0 ip address 192.12.12.2 255.255.255.0 serial restart-delay 0 ! interface FastEthernet2/0 ip address 192.23.23.2 255.255.255.0 duplex auto speed auto ! router ospf 1 router-id 2.2.2.2 log-adjacency-changes redistribute bgp 100 metric 100 metric-type 1 subnets route-map BGP-To_OSPF network 192.23.23.2 0.0.0.0 area 0 ! router bgp 100 no synchronization bgp router-id 2.2.2.2 bgp log-neighbor-changes bgp redistribute-internal neighbor 192.12.12.1 remote-as 100 no auto-summary ! ip prefix-list B2O seq 5 permit 172.16.0.0/16 ! route-map BGP-To_OSPF permit 10 match ip address prefix-list B2O Router R3 interface FastEthernet1/0 ip address 192.23.23.3 255.255.255.0 duplex auto speed auto ! router ospf 1 log-adjacency-changes network 192.23.23.3 0.0.0.0 area 0 https://supportforums.cisco.com/docs/DOC-18319 (iBGP)

8. Redistribution of BGP routes into OSPF https://supportforums.cisco.com/docs/DOC-18319 R1#sh ip bgp sum BGP router identifier 1.1.1.1, local AS number 100 BGP table version is 3, main routing table version 3 2 network entries using 240 bytes of memory 2 path entries using 104 bytes of memory 1/1 BGP path/bestpath attribute entries using 124 bytes of memory 0 BGP route-map cache entries using 0 bytes of memory 0 BGP filter-list cache entries using 0 bytes of memory BGP using 468 total bytes of memory BGP activity 2/0 prefixes, 2/0 paths, scan interval 60 secs Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd 192.12.12.2 4 100 117 119 3 0 0 01:43:47 0

9. Redistribution of BGP routes into OSPF https://supportforums.cisco.com/docs/DOC-18319 R3#sh ip route Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route, + - replicated route Gateway of last resort is not set O E1 172.16.0.0/16 [110/101] via 192.23.23.2, 00:57:55, FastEthernet1/0 192.23.23.0/24 is variably subnetted, 2 subnets, 2 masks C 192.23.23.0/24 is directly connected, FastEthernet1/0 L 192.23.23.3/32 is directly connected, FastEthernet1/0