virtual-link
Dans notre exemple, l’Area 3 n’a pas de connexion direct (physique ou logique) avec l’Aera0.
L’ Area 1 est donc en charge de créer un lien logique entre R1 et R2 :
R1#conf t R1(config)#router ospf 1 R1(config-router)#area 1 virtual-link 2.2.2.2 R2#conf t R2(config)#router ospf 1 R2(config-router)#area 1 virtual-link 1.1.1.1
Vérification
R2#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 1.1.1.1 0 FULL/ - - 10.1.12.1 OSPF_VL0 3.3.3.3 1 FULL/DR 00:00:30 10.1.23.3 FastEthernet0/0 1.1.1.1 0 FULL/ - 00:00:37 10.1.12.1 Serial0/0.21 R2#show ip route ospf 1.0.0.0/24 is subnetted, 1 subnets O 1.1.1.0 [110/65] via 10.1.12.1, 00:02:15, Serial0/0.21 3.0.0.0/24 is subnetted, 1 subnets O 3.3.3.0 [110/2] via 10.1.23.3, 00:02:15, FastEthernet0/0 4.0.0.0/24 is subnetted, 1 subnets O IA 4.4.4.0 [110/12] via 10.1.23.3, 00:02:15, FastEthernet0/0 10.0.0.0/24 is subnetted, 4 subnets O IA 10.1.1.0 [110/65] via 10.1.12.1, 00:00:17, Serial0/0.21 O IA 10.1.34.0 [110/11] via 10.1.23.3, 00:02:15, FastEthernet0/0 30.0.0.0/24 is subnetted, 1 subnets O IA 30.3.3.0 [110/2] via 10.1.23.3, 00:02:15, FastEthernet0/0
GRE Tunnels
Dans notre exemple, l’Area 4 n’a pas de connexion direct (physique ou logique) avec l’Aera0.
Il est possible de créer un tunnel GRE entre R4 et R5 afin de « prolonger » l’Area 0 jusqu’a R4
R3#conf t R3(config)#int tunnel 1 R3(config-if)#ip address 100.0.0.1 255.255.255.0 R3(config-if)#tunnel source 10.1.34.3 R3(config-if)#tunnel destination 10.1.34.4 R3(config)#router ospf 1 R3(config-router)#network 100.0.0.1 0.0.0.0 area 0 R4#conf t R4(config)#int tunnel 1 R4(config-if)#ip address 100.0.0.2 255.255.255.0 R4(config-if)#tunnel source 10.1.34.4 R4(config-if)#tunnel destination 10.1.34.3 R4(config-if)#router ospf 1 R4(config-router)#network 100.0.0.2 0.0.0.0 area 0
Vérifications:
R3#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 4.4.4.4 0 FULL/ - 00:00:38 100.0.0.2 Tunnel1 2.2.2.2 1 FULL/BDR 00:00:35 10.1.23.2 FastEthernet0/0 4.4.4.4 0 FULL/ - 00:00:33 10.1.34.4 Serial1/0.34
R3#show ip route 5.5.5.5 Routing entry for 5.5.5.0/24 Known via "ospf 1", distance 110, metric 11113, type inter area Last update from 100.0.0.2 on Tunnel1, 00:01:21 ago Routing Descriptor Blocks: * 100.0.0.2, from 4.4.4.4, 00:01:21 ago, via Tunnel1 Route metric is 11113, traffic share count is 1
R1#ping 5.5.5.5 source 10.1.1.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds: Packet sent with a source address of 10.1.1.1 !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 128/128/128 ms