Estableceremos un tunel gre entre dos sedes que solo se comunican por IPv4.
Usaremos el ejemplo:
Todo el camino es IPv4, podemos establecer un tunel gre entre R1 y R5.
R1#sh run int tun 0
Building configuration...
Current configuration : 151 bytes
!
interface Tunnel0
no ip address
ipv6 address FEC0:15::1/64
tunnel source 19.19.12.1
tunnel destination 19.19.45.5
tunnel mode gre ip ! es la encapsulacoin por defecto
end
R5#sh run int tun 0
Building configuration...
Current configuration : 151 bytes
!
interface Tunnel0
no ip address
ipv6 address FEC0:15::5/64
tunnel source 19.19.45.5
tunnel destination 19.19.12.1
tunnel mode gre ip ! es la encapsulacoin por defecto
end
Verificamos
R5#sh int tun0
Tunnel0 is up, line protocol is up
Hardware is Tunnel
MTU 1514 bytes, BW 9 Kbit/sec, DLY 500000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation TUNNEL, loopback not set
Keepalive not set
Tunnel source 19.19.45.5 (FastEthernet0/1), destination 19.19.12.1
Tunnel protocol/transport GRE/IP
R5#ping FEC0:15::1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to FEC0:15::1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 72/83/96 ms
R1#ping fec0:15::5
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to FEC0:15::5, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 80/84/92 ms
Como es un tunel gre tenemos la ventaja de que podemos utilizar protocolos de enrutamiento dinámicos sin preocuparnos de que anuncien sus rutas por multicast o broadcast.
R5(config)#ipv6 router ospf 10
R5(config-rtr)#int lo 0
R5(config-if)#ipv ospf 10 area 0
R5(config-if)#int tun0
R5(config-if)#ipv ospf 10 area 0
Similar en R1
R1(config)#ipv6 router ospf 10
R1(config-rtr)#int lo 0
R1(config-if)#ipv ospf 10 area 0
R1(config-if)#int tun0
R1(config-if)#ipv ospf 10 area 0
Ospf comienza a funcionar
R5#sh ipv6 ospf nei
Neighbor ID Pri State Dead Time Interface ID Interface
19.19.12.1 1 FULL/ - 00:00:34 10 Tunnel0
R5#sh ipv6 route ospf
IPv6 Routing Table - 5 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
U - Per-user Static route, M - MIPv6
I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary
O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
D - EIGRP, EX - EIGRP external
O 2013::1/128 [110/11111]
via FE80::C002:11FF:FE00:0, Tunnel0
Y podemos probar hacer ping de loopback a loopback
R1#ping 2013::5 source lo0 repeat 100
Type escape sequence to abort.
Sending 100, 100-byte ICMP Echos to 2013::5, timeout is 2 seconds:
Packet sent with a source address of 2013::1
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Success rate is 100 percent (100/100), round-trip min/avg/max = 68/81/96 ms