4-7 default-information originate route-map route-map-name

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4-7 default-information originate route-map route-map- name

Syntax Description:

  • route-map-name ” OSPF will generate a default route only if the conditions of the route map are satisfied. If the keyword always is used, the default route will be advertised regardless of the conditions in the route map.

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 Advertisement

In 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

graphics/04fig05.gif

 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   
Verification

Verify 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
Step 1. Verify that there is a neighbor relationship between the OSPF routers using the show ip ospf neighbors command.

Step 2. Verify the syntax and conditions of the route map.

Step 3. If you are using the always form of the command, then the default route will be advertised regardless of the conditions in the route map.

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Cisco[r] OSPF Command and Configuration Handbook
Cisco OSPF Command and Configuration Handbook (paperback)
ISBN: 1587055406
EAN: 2147483647
Year: 2002
Pages: 236

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