Se tratar de áreas OSPF diferentes não funcionaria o "filter-list" no R3 da topologia abaixo na qual é o Service Provider.
O "filter-list" só funcionaria no caso abaixo dentro da rede do cliente (Router R4) da Área 3 para Área 0 e mesmo assim o "filter-list" só filtra rotas "O IA", ou seja, inter-areas (LSA 3 - network). Se houver rotas redistribuidas do BGP no OSPF por exemplo (caso abaixo) que são "LSA 5 - external", não serão filtradas.
Veja abaixo:
router ospf 200
log-adjacency-changes
redistribute connected subnets
redistribute bgp 65000 subnets route-map bgp3ospf
network 10.198.34.76 0.0.0.3 area 3
!
router bgp 65000
bgp log-neighbor-changes
neighbor 200.200.1.1 remote-as 65000
!
address-family ipv4
redistribute connected
redistribute static
redistribute ospf 200 match internal external 1 external 2 route-map ospf3bgp
neighbor 200.200.1.1 activate
neighbor 200.200.1.1 send-community
neighbor 200.200.1.1 allowas-in
no auto-summary
no synchronization
exit-address-family
no cdp log mismatch duplex
!
route-map ospf3bgp deny 10
match tag 3110
!
route-map ospf3bgp permit 20
set tag 390
!
route-map bgp3ospf deny 10
match tag 390
!
route-map bgp3ospf permit 20
set tag 3110
Configuração R4:
router ospf 200
log-adjacency-changes
area 0 filter-list prefix teste in
redistribute connected subnets
network 4.4.4.0 0.0.0.255 area 0
network 10.198.34.76 0.0.0.3 area 3
!
no ip http server
no ip http secure-server
!
!
!
!
ip prefix-list teste seq 5 deny 10.198.34.76/30
ip prefix-list teste seq 10 permit 0.0.0.0/0 le 32
no cdp log mismatch duplex
Configuração R5:
router ospf 200
log-adjacency-changes
network 4.4.4.0 0.0.0.255 area 0
Tabela de roteamento em R5 ANTES do filtro em VERMELHO:
R5#sh 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
33.0.0.0/32 is subnetted, 1 subnets
O E2 33.33.33.33 [110/20] via 4.4.4.1, 00:00:07, FastEthernet1/0
4.0.0.0/24 is subnetted, 1 subnets
C 4.4.4.0 is directly connected, FastEthernet1/0
200.200.1.0/30 is subnetted, 1 subnets
O E2 200.200.1.0 [110/20] via 4.4.4.1, 00:00:07, FastEthernet1/0
10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
O E2 10.198.39.159/32 [110/20] via 4.4.4.1, 00:00:07, FastEthernet1/0
O IA 10.198.34.76/30 [110/2] via 4.4.4.1, 00:00:07, FastEthernet1/0
Tabela de roteamento em R5 DEPOIS do filtro em VERMELHO:
R5#sh 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
33.0.0.0/32 is subnetted, 1 subnets
O E2 33.33.33.33 [110/20] via 4.4.4.1, 00:00:52, FastEthernet1/0
4.0.0.0/24 is subnetted, 1 subnets
C 4.4.4.0 is directly connected, FastEthernet1/0
200.200.1.0/30 is subnetted, 1 subnets
O E2 200.200.1.0 [110/20] via 4.4.4.1, 00:00:52, FastEthernet1/0
10.0.0.0/32 is subnetted, 1 subnets
O E2 10.198.39.159 [110/20] via 4.4.4.1, 00:00:52, FastEthernet1/0
R5#
Para um filtro do Service Provider para o Cliente B será efetivo um filtro via DISTRIBUTE-LIST.
Veja abaixo:
Configuração do Roteador R3:
ip prefix-list teste2 permit 33.33.33.33/32
ip prefix-list teste2 deny 0.0.0.0/0 le 32
router ospf 200
distribute-list prefix teste2 out
Tabela de roteamento de R5 após filtro de R3:
R5#sh 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
33.0.0.0/32 is subnetted, 1 subnets
O E2 33.33.33.33 [110/20] via 4.4.4.1, 00:34:46, FastEthernet1/0
4.0.0.0/24 is subnetted, 1 subnets
C 4.4.4.0 is directly connected, FastEthernet1/0
10.0.0.0/32 is subnetted, 1 subnets
O E2 10.198.39.159 [110/20] via 4.4.4.1, 00:34:46, FastEthernet1/0
R5#
R5#
Pode-se verificar que a rede 200.200.1.0/30 (O E2) saiu da tabela, ficando a rede 33.33.33.33/32 (O E2) aprendida de R3.
A Rede 10.198.39.159/32 (O E2) permanece pois é aprendida de R4.
