OSPF Area Type

Posted on 13 avril 2012 by Fred J.

OSPF Area Type

 

  • Stub
  • Totally Stubby
  • NSSA

 

 

Dans notre exemple :

 

Le routeur R5 annonce en OSPF 10 sous réseaux 5.5.0.0 /24 à 5.5.9.0 /24
Le routeur R1 annonce en OSPF 10 sous réseaux 1.1.0.0 /24 à 1.1.9.0 /24
Le routeur R1 redistribue dans OSPF 5 sous réseaux 10.1.0.0 à 10.1.4.0/24

Table routage de R5 (Area 2) :

R5#show ip route
Codes: 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

Gateway of last resort is not set

     1.0.0.0/24 is subnetted, 10 subnets
O IA    1.1.0.0 [110/117] via 10.1.45.4, 00:00:04, FastEthernet0/0
O IA    1.1.1.0 [110/117] via 10.1.45.4, 00:00:04, FastEthernet0/0
O IA    1.1.2.0 [110/117] via 10.1.45.4, 00:00:04, FastEthernet0/0
O IA    1.1.3.0 [110/117] via 10.1.45.4, 00:00:04, FastEthernet0/0
O IA    1.1.4.0 [110/117] via 10.1.45.4, 00:00:04, FastEthernet0/0
O IA    1.1.5.0 [110/117] via 10.1.45.4, 00:00:04, FastEthernet0/0
O IA    1.1.6.0 [110/117] via 10.1.45.4, 00:00:04, FastEthernet0/0
O IA    1.1.7.0 [110/117] via 10.1.45.4, 00:00:05, FastEthernet0/0
O IA    1.1.8.0 [110/117] via 10.1.45.4, 00:00:05, FastEthernet0/0
O IA    1.1.9.0 [110/117] via 10.1.45.4, 00:00:05, FastEthernet0/0
     2.0.0.0/24 is subnetted, 1 subnets
O IA    2.2.2.0 [110/53] via 10.1.45.4, 00:00:05, FastEthernet0/0
     3.0.0.0/24 is subnetted, 1 subnets
O IA    3.3.3.0 [110/52] via 10.1.45.4, 00:00:05, FastEthernet0/0
     4.0.0.0/24 is subnetted, 1 subnets
O IA    4.4.4.0 [110/2] via 10.1.45.4, 00:00:05, FastEthernet0/0
     5.0.0.0/24 is subnetted, 10 subnets
C       5.5.0.0 is directly connected, Loopback0
C       5.5.1.0 is directly connected, Loopback1
C       5.5.2.0 is directly connected, Loopback2
C       5.5.3.0 is directly connected, Loopback3
C       5.5.4.0 is directly connected, Loopback4
C       5.5.5.0 is directly connected, Loopback5
C       5.5.6.0 is directly connected, Loopback6
C       5.5.7.0 is directly connected, Loopback7
C       5.5.8.0 is directly connected, Loopback8
C       5.5.9.0 is directly connected, Loopback9
     22.0.0.0/24 is subnetted, 1 subnets
O IA    22.2.2.0 [110/53] via 10.1.45.4, 00:00:06, FastEthernet0/0
     10.0.0.0/24 is subnetted, 9 subnets
O IA    10.1.12.0 [110/116] via 10.1.45.4, 00:00:06, FastEthernet0/0
O E2    10.1.3.0 [110/20] via 10.1.45.4, 00:00:06, FastEthernet0/0
O E2    10.1.2.0 [110/20] via 10.1.45.4, 00:00:06, FastEthernet0/0
O E2    10.1.1.0 [110/20] via 10.1.45.4, 00:00:06, FastEthernet0/0
O E2    10.1.0.0 [110/20] via 10.1.45.4, 00:00:06, FastEthernet0/0
O E2    10.1.4.0 [110/20] via 10.1.45.4, 00:00:06, FastEthernet0/0
O IA    10.1.23.0 [110/52] via 10.1.45.4, 00:00:06, FastEthernet0/0
C       10.1.45.0 is directly connected, FastEthernet0/0
O IA    10.1.34.0 [110/51] via 10.1.45.4, 00:00:06, FastEthernet0/0
     44.0.0.0/24 is subnetted, 1 subnets
O       44.4.4.0 [110/2] via 10.1.45.4, 00:00:06, FastEthernet0/0

Configuration de l’AREA 2 en STUB

  • Tous les routers de l’Area doivent être configurés avec la commande « area x stub »
  • Les LSA de type 4 et 5 (E1 et E2) ne sont plus reçus
  • Une route par défaut est injecté par l’ABR
R4#conf t
R4(config)#router ospf 1
R4(config-router)#area 2 stub

R5#conf t
R5(config)#router ospf 1
R5(config-router)#area 2 stub

Vérification :

R5#show ip route ospf
     1.0.0.0/24 is subnetted, 10 subnets
O IA    1.1.0.0 [110/117] via 10.1.45.4, 00:00:13, FastEthernet0/0
O IA    1.1.1.0 [110/117] via 10.1.45.4, 00:00:13, FastEthernet0/0
O IA    1.1.2.0 [110/117] via 10.1.45.4, 00:00:13, FastEthernet0/0
O IA    1.1.3.0 [110/117] via 10.1.45.4, 00:00:13, FastEthernet0/0
O IA    1.1.4.0 [110/117] via 10.1.45.4, 00:00:13, FastEthernet0/0
O IA    1.1.5.0 [110/117] via 10.1.45.4, 00:00:13, FastEthernet0/0
O IA    1.1.6.0 [110/117] via 10.1.45.4, 00:00:13, FastEthernet0/0
O IA    1.1.7.0 [110/117] via 10.1.45.4, 00:00:13, FastEthernet0/0
O IA    1.1.8.0 [110/117] via 10.1.45.4, 00:00:13, FastEthernet0/0
O IA    1.1.9.0 [110/117] via 10.1.45.4, 00:00:13, FastEthernet0/0
     2.0.0.0/24 is subnetted, 1 subnets
O IA    2.2.2.0 [110/53] via 10.1.45.4, 00:00:13, FastEthernet0/0
     3.0.0.0/24 is subnetted, 1 subnets
O IA    3.3.3.0 [110/52] via 10.1.45.4, 00:00:13, FastEthernet0/0
     4.0.0.0/24 is subnetted, 1 subnets
O IA    4.4.4.0 [110/2] via 10.1.45.4, 00:00:13, FastEthernet0/0
     22.0.0.0/24 is subnetted, 1 subnets
O IA    22.2.2.0 [110/53] via 10.1.45.4, 00:00:14, FastEthernet0/0
     10.0.0.0/24 is subnetted, 4 subnets
O IA    10.1.12.0 [110/116] via 10.1.45.4, 00:00:14, FastEthernet0/0
O IA    10.1.23.0 [110/52] via 10.1.45.4, 00:00:14, FastEthernet0/0
O IA    10.1.34.0 [110/51] via 10.1.45.4, 00:00:14, FastEthernet0/0
     44.0.0.0/24 is subnetted, 1 subnets
O       44.4.4.0 [110/2] via 10.1.45.4, 00:00:14, FastEthernet0/0
O*IA 0.0.0.0/0 [110/2] via 10.1.45.4, 00:00:14, FastEthernet0/0

Configuration de l’AREA 2 en « Totally Stubby »

  • L’ABR doit être configuré avec la commande « area x stub no-summary »
  • Les autres routeurs de l’Area doivent être configurés avec la commande « area x stub »
  • Les LSA de type 3, 4 et 5 ne sont plus reçus
  • Une route par défaut est injecté par l’ABR
R4#conf t
R4(config)#router ospf 1
R4(config-router)#area 2 stub no-summary

Vérification

R5#show ip route ospf
     44.0.0.0/24 is subnetted, 1 subnets
O       44.4.4.0 [110/2] via 10.1.45.4, 00:00:49, FastEthernet0/0
O*IA 0.0.0.0/0 [110/2] via 10.1.45.4, 00:00:04, FastEthernet0/0

Configuration de l’AREA 2 en « NSSA »

  • Tous les routers de l’Area doivent être configurés avec la commande « area x nssa »
  • Seuls les LSA de type 1,2,3 et 7 sont traités
  • Par défaut, en mode NSSA, aucunne route par défaut n’est injectée
R4#conf t
R4(config)#router ospf 1
R4(config-router)#area 2 nssa

R5#conf t
R5(config)#router ospf 1
R5(config-router)#area 2 nssa

Vérification

R5#show ip route ospf
     1.0.0.0/24 is subnetted, 10 subnets
O IA    1.1.0.0 [110/117] via 10.1.45.4, 00:01:12, FastEthernet0/0
O IA    1.1.1.0 [110/117] via 10.1.45.4, 00:01:12, FastEthernet0/0
O IA    1.1.2.0 [110/117] via 10.1.45.4, 00:01:12, FastEthernet0/0
O IA    1.1.3.0 [110/117] via 10.1.45.4, 00:01:12, FastEthernet0/0
O IA    1.1.4.0 [110/117] via 10.1.45.4, 00:01:12, FastEthernet0/0
O IA    1.1.5.0 [110/117] via 10.1.45.4, 00:01:12, FastEthernet0/0
O IA    1.1.6.0 [110/117] via 10.1.45.4, 00:01:12, FastEthernet0/0
O IA    1.1.7.0 [110/117] via 10.1.45.4, 00:01:12, FastEthernet0/0
O IA    1.1.8.0 [110/117] via 10.1.45.4, 00:01:12, FastEthernet0/0
O IA    1.1.9.0 [110/117] via 10.1.45.4, 00:01:12, FastEthernet0/0
     2.0.0.0/24 is subnetted, 1 subnets
O IA    2.2.2.0 [110/53] via 10.1.45.4, 00:01:12, FastEthernet0/0
     3.0.0.0/24 is subnetted, 1 subnets
O IA    3.3.3.0 [110/52] via 10.1.45.4, 00:01:12, FastEthernet0/0
     4.0.0.0/24 is subnetted, 1 subnets
O IA    4.4.4.0 [110/2] via 10.1.45.4, 00:01:12, FastEthernet0/0
     22.0.0.0/24 is subnetted, 1 subnets
O IA    22.2.2.0 [110/53] via 10.1.45.4, 00:01:13, FastEthernet0/0
     10.0.0.0/24 is subnetted, 4 subnets
O IA    10.1.12.0 [110/116] via 10.1.45.4, 00:01:13, FastEthernet0/0
O IA    10.1.23.0 [110/52] via 10.1.45.4, 00:01:13, FastEthernet0/0
O IA    10.1.34.0 [110/51] via 10.1.45.4, 00:01:13, FastEthernet0/0
     44.0.0.0/24 is subnetted, 1 subnets
O       44.4.4.0 [110/2] via 10.1.45.4, 00:01:13, FastEthernet0/0

NSSA: Injection d’une route par défaut

R4(config)#router ospf 1
R4(config-router)#area 1 nssa default-information-originate

R5#show ip route ospf | inc 0.0.0.0/0
O*N2 0.0.0.0/0 [110/1] via 10.1.45.4, 00:01:25, FastEthernet0/0

NSSA: Filtrer les LSA de type 3

R4(config)#router ospf 1
R4(config-router)#area 2 nssa no-summary

R5#show ip route ospf
     44.0.0.0/24 is subnetted, 1 subnets
O       44.4.4.0 [110/2] via 10.1.45.4, 00:13:18, FastEthernet0/0
O*IA 0.0.0.0/0 [110/2] via 10.1.45.4, 00:00:02, FastEthernet0/0

Modification du cout OSPF de la route par défaut

R4(config)#router ospf 1
R4(config-router)#area 2 default-cost 50

R5#show ip route ospf
     44.0.0.0/24 is subnetted, 1 subnets
O       44.4.4.0 [110/2] via 10.1.45.4, 00:17:21, FastEthernet0/0
O*IA 0.0.0.0/0 [110/51] via 10.1.45.4, 00:00:05, FastEthernet0/0
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