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4-7 default-information originate route-map route-map- nameSyntax Description:
Purpose: The advertisement of a default route can be made conditional using a route map. If the conditions of the route map are satisfied, then the default route will be advertised into the OSPF domain. Initial Cisco IOS Software Release: 10.0 Configuration Example: Using a Route Map for Conditional Default Route AdvertisementIn Figure 4-5, Router B is receiving the route 3.3.3.0/30 from Router C via EIGRP. This network will carry all default traffic from the OPSF domain. If this network is down then you don't want the traffic from the OSPF domain to be sent to Router C. A route map can be used on Router B to make a conditional advertisement of a default route. For this example, the condition will be the existence of the 3.3.3.0/30 in the IP routing table on Router B. Figure 4-5. When OSPF Advertises a Default Route, the Advertising Router Becomes an ASBR. The Advertisement of a Default Route Can Be Made Conditional Using a Route Map
Router A interface Loopback0 ip address 1.1.1.1 255.255.255.255 ! interface Ethernet0/0 ip address 172.16.1.1 255.255.255.0 ! router ospf 1 network 1.1.1.1 0.0.0.0 area 0 network 172.16.1.0 0.0.0.255 area 0 ________________________________________________________________________________ Router B interface Loopback0 ip address 2.2.2.2 255.255.255.255 ! interface Ethernet0 ip address 172.16.1.2 255.255.255.0 ! interface Serial1 bandwidth 64 ip address 10.1.1.5 255.255.255.252 clockrate 64000 ! router eigrp 1 network 10.0.0.0 router ospf 1 network 2.2.2.2 0.0.0.0 area 0 network 172.16.1.0 0.0.0.255 area 0 ________________________________________________________________________________ Router C interface Loopback0 description Simulate the network 3.3.3.0/30 ip address 3.3.3.1 255.255.255.252 ! interface Serial0 bandwidth 64 ip address 10.1.1.6 255.255.255.252 ! router eigrp 1 network 3.0.0.0 network 10.0.0.0 no auto-summary Verify that Routers A and B have established an OSPF neighbor relationship. rtrA# show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 2.2.2.2 1 FULL/BDR 00:00:30 172.16.1.2 Ethernet0/0 ________________________________________________________________________________ rtrB# show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 1.1.1.1 1 FULL/DR 00:00:38 172.16.1.1 Ethernet0 Verify that Routers B and C have formed an EIGRP relationship. rtrB# show ip eigrp neighbors IP-EIGRP neighbors for process 1 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 0 10.1.1.6 Se1 10 00:13:27 399 2394 0 4 ________________________________________________________________________________ rtrC# show ip eigrp neighbors IP-EIGRP neighbors for process 1 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 0 10.1.1.5 Se0 11 00:13:53 28 2280 0 6 Verify that Router B is receiving the 3.3.3.0/30 network from Router C. rtrB# show 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 N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR Gateway of last resort is not set 1.0.0.0/32 is subnetted, 1 subnets O 1.1.1.1 [110/11] via 172.16.1.1, 00:13:37, Ethernet0 2.0.0.0/32 is subnetted, 1 subnets C 2.2.2.2 is directly connected, Loopback0 3.0.0.0/30 is subnetted, 1 subnets D 3.3.3.0 [90/40640000] via 10.1.1.6, 00:13:38, Serial1 172.16.0.0/24 is subnetted, 1 subnets C 172.16.1.0 is directly connected, Ethernet0 10.0.0.0/30 is subnetted, 1 subnets C 10.1.1.4 is directly connected, Serial1 Modify the configuration on router B so that OSPF will conditionally advertise a default route into the OSPF domain based on the existence of the 3.3.3.0/30 network. Router B router ospf 1 network 2.2.2.2 0.0.0.0 area 0 network 172.16.1.0 0.0.0.255 area 0 default-information originate route-map exist ! access-list 1 permit 3.3.3.0 0.0.0.3 ! route-map exist permit 10 match ip address 1 VerificationVerify that the default route is in the IP routing table on Router A. rtrA# show 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 N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR Gateway of last resort is 172.16.1.2 to network 0.0.0.0 1.0.0.0/32 is subnetted, 1 subnets C 1.1.1.1 is directly connected, Loopback0 2.0.0.0/32 is subnetted, 1 subnets O 2.2.2.2 [110/11] via 172.16.1.2, 00:15:57, Ethernet0/0 172.16.0.0/24 is subnetted, 1 subnets C 172.16.1.0 is directly connected, Ethernet0/0 O*E2 0.0.0.0/0 [110/1] via 172.16.1.2, 00:15:57, Ethernet0/0 Test the route map by shutting down the loopback0 interface on Router C so the 3.3.3.0/30 will no longer be advertised by EIGRP. This should prevent Router B from advertising the default route. Router C interface Loopback0 shutdown Verify that the 3.3.3.0/30 network is not in the IP routing table on Router B. rtrB# show 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 N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR Gateway of last resort is not set 1.0.0.0/32 is subnetted, 1 subnets O 1.1.1.1 [110/11] via 172.16.1.1, 00:19:58, Ethernet0 2.0.0.0/32 is subnetted, 1 subnets C 2.2.2.2 is directly connected, Loopback0 172.16.0.0/24 is subnetted, 1 subnets C 172.16.1.0 is directly connected, Ethernet0 10.0.0.0/30 is subnetted, 1 subnets C 10.1.1.4 is directly connected, Serial1 Verify that the default route is not being advertised to Router A. rtrA# show 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 N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR Gateway of last resort is not set 1.0.0.0/32 is subnetted, 1 subnets C 1.1.1.1 is directly connected, Loopback0 2.0.0.0/32 is subnetted, 1 subnets O 2.2.2.2 [110/11] via 172.16.1.2, 00:20:13, Ethernet0/0 172.16.0.0/24 is subnetted, 1 subnets C 172.16.1.0 is directly connected, Ethernet0/0 Reenable the loopback interface on Router C and verify that the default route is being advertised. Router C interface Loopback0 no shutdown ________________________________________________________________________________ rtrB# show 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 N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR Gateway of last resort is not set 1.0.0.0/32 is subnetted, 1 subnets O 1.1.1.1 [110/11] via 172.16.1.1, 00:22:27, Ethernet0 2.0.0.0/32 is subnetted, 1 subnets C 2.2.2.2 is directly connected, Loopback0 3.0.0.0/30 is subnetted, 1 subnets D 3.3.3.0 [90/40640000] via 10.1.1.6, 00:00:05, Serial1 172.16.0.0/24 is subnetted, 1 subnets C 172.16.1.0 is directly connected, Ethernet0 10.0.0.0/30 is subnetted, 1 subnets C 10.1.1.4 is directly connected, Serial1 ________________________________________________________________________________ rtrA# show 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 N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default U - per-user static route, o - ODR Gateway of last resort is 172.16.1.2 to network 0.0.0.0 1.0.0.0/32 is subnetted, 1 subnets C 1.1.1.1 is directly connected, Loopback0 2.0.0.0/32 is subnetted, 1 subnets O 2.2.2.2 [110/11] via 172.16.1.2, 00:22:44, Ethernet0/0 172.16.0.0/24 is subnetted, 1 subnets C 172.16.1.0 is directly connected, Ethernet0/0 O*E2 0.0.0.0/0 [110/1] via 172.16.1.2, 00:01:00, Ethernet0/0 Troubleshooting
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