Rotas Estáticas IPv6 usando endereços Link Local

É possível criar rotas estáticas IPv6 sem ter endereços roteáveis atribuídos nas interfaces físicas.

Nas redes IPv4 podemos usar o comando Ip unnumbered em routers Cisco para usar o IP de uma outra interface (como uma loopback) em um link ponto-a-ponto, para economizar endereços.

Nas redes IPv6, podemos usar interfaces que só possuem endereços Link Local (Fe80:: - não roteáveis) e, mesmo assim, criar rotas estáticas para alcançar outras redes, utilizando tais interfaces como gateway.

Primeiramente, vamos inserir a configuração básica nos routers Internet e Borda:

ena
conf t
hostname INTERNET
ipv6 unicast-routing
int f0/0
ipv6 enable
no shut
int lo1
ipv6 address 2001:db9:100:1::1/128
end
wr

ena
conf t
hostname BORDA
ipv6 unicast-routing
int f0/0
ipv6 enable
no shut
int lo1
ipv6 address 2001:db8:100:1::1/128
end
wr

O comando IPv6 enable faz com que a Interface, apesar de não ter um IPv6 roteado, gere um endereço Link Local a partir de seu MAC-address.

Agora precisamos identificar que endereço Link-Local foi gerado em cada router. Use os comandos abaixo:

INTERNET#show ipv6 int f0/0
FastEthernet0/0 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::C801:1FFF:FEA8:0
No Virtual link-local address(es):
No global unicast address is configured
Joined group address(es):
FF02::1
FF02::2
FF02::1:FFA8:0
MTU is 1500 bytes
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ICMP unreachables are sent
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds (using 30000)
ND advertised reachable time is 0 (unspecified)
ND advertised retransmit interval is 0 (unspecified)
ND router advertisements are sent every 200 seconds
ND router advertisements live for 1800 seconds
ND advertised default router preference is Medium
Hosts use stateless autoconfig for addresses.

BORDA#show ipv6 interface f0/0
FastEthernet0/0 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::C802:17FF:FEAC:0
No Virtual link-local address(es):
No global unicast address is configured
Joined group address(es):
FF02::1
FF02::2
FF02::1:FFAC:0
MTU is 1500 bytes
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ICMP unreachables are sent
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds (using 30000)
ND advertised reachable time is 0 (unspecified)
ND advertised retransmit interval is 0 (unspecified)
ND router advertisements are sent every 200 seconds
ND router advertisements live for 1800 seconds
ND advertised default router preference is Medium
Hosts use stateless autoconfig for addresses.


Pois bem, para criar as rotas estáticas, devemos informar tanto a interface de saída quanto o endereço link local do vizinho que queremos alcançar.

Crie uma rota estática no router Internet para que ele alcance a Loopback do roteador borda:

INTERNET(config)#
ipv6 route 2001:DB8:100:1::1/128 FastEthernet0/0 FE80::C802:17FF:FEAC:0

Crie uma rota padrão no router Borda para que ele encaminhe todos os pacotes roteados para o router Internet:

BORDA(config)#
ipv6 route ::/0 FastEthernet0/0 FE80::C801:1FFF:FEA8:0


Pronto! Faça os testes de ping e verifique se os roteadores conseguem alcançar as loopbacks dos vizinhos:

BORDA#ping 2001:db9:100:1::1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB9:100:1::1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/33/80 ms

INTERNET#ping 2001:db8:100:1::1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:100:1::1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/33/80 ms

Have Fun!!!