IPv6 over IPv4 Tunneling

Overlay tunneling encapsulates IPv6 packets in IPv4 packets for delivery across an IPv4 infrastructure (a core network or the figure below). By using overlay tunnels, you can communicate with isolated IPv6 networks without upgrading the IPv4 infrastructure between them. Overlay tunnels can be configured between border devices or between a border device and a host; however, both tunnel endpoints must support both the IPv4 and IPv6 protocol stacks. IPv6 supports the following types of overlay tunneling mechanisms:

• Manual
• Generic routing encapsulation (GRE)
• IPv4-compatible
• 6to4
• Intrasite Automatic Tunnel Addressing Protocol (ISATAP) 

 

 

The config is simple.

R1# show running-config

!
ip cef
ipv6 unicast-routing
ipv6 cef
!
interface Loopback0
no ip address
ipv6 address 2001:DB8:1::1/64
ipv6 ospf 1 area 0
!
interface Tunnel0
no ip address
ipv6 address 2001:DB8:10::1/64
ipv6 ospf 1 area 0
tunnel source Ethernet0/0
tunnel mode ipv6ip
tunnel destination 209.165.201.6
!
interface Ethernet0/0
ip address 209.165.201.1 255.255.255.252
!
router ospfv3 1
!
address-family ipv6 unicast
exit-address-family
!
router bgp 100
bgp router-id 1.1.1.1
bgp log-neighbor-changes
neighbor 209.165.201.2 remote-as 200
!
address-family ipv4
network 209.165.201.0 mask 255.255.255.252
neighbor 209.165.201.2 activate
exit-address-family
!
end

R3# show ipv6 int brief

Ethernet0/1            [up/up]
    unassigned
Loopback0              [up/up]
    FE80::A8BB:CCFF:FE00:3000
    2001:DB8:3::3
Tunnel0                [up/up]
    FE80::D1A5:C906
    2001:DB8:10::2

R3# tracer 2001:DB8:1::1

Tracing the route to 2001:DB8:1::1

  1 2001:DB8:10::1 2 msec 2 msec 1 msec

R1# debug ipv6 icmp

*Apr 20 18:04:41.250: ICMPv6: Sent Unreachable code 4, Src=2001:DB8:10::1, Dst=2001:DB8:10::2
*Apr 20 18:04:41.251: ICMPv6: Sent Unreachable code 4, Src=2001:DB8:10::1, Dst=2001:DB8:10::2

.!!!!

..!..

biOos