IPv6 NAT-PT

In the recent posts, we discussed how we can transport IPv6 traffic over IPv4 backbone using the tunneling techniques. 

These techniques will not work if we have one part of network which can only run IPv4 and the other part can only run IPv6. Since IPv4 and IPv6 are not compatible with each other, we have to use some sort of translation mechanism. The way we can achieve this is through NAT-PT (NAT protocol translation).

Let's look at the below topology and see how NAT-PT can be implemented.

We have three routers R1, R2 and R3. We are running RIPng and RIPv2 between R1-R2 and R2-R3 respectively. R1 is only aware about IPv6 addresses, similarly R3 is only aware about IPv4 addresses.

Our goal is to establish reachability between the IPv6 loopback (2001:1111::1/128) of R1 to IPv4 loopback (3.3.3.3/32) of R3.

IPv6 tunneling over IPv4 - 6to4 Autotunnel

In the previous post, we looked at the IPv6 tunneling technique using IPv4 manual tunnels. We will now see how dynamic multipoint IPv6 tunnel works.

6to4 tunnels allow for the dynamic creation of IPv6 within IPv4 tunnels. Manual tunnel is normally used as point-to-point however 6to4 tunnels can be point-to-multipoint.

The 2002::/16 range has been reserved to use for tunneling. We will have to add the IPv4 address into this range to generate /48 prefix. i.e. if the IPv4 address of the border router is 192.168.1.1 then the 6to4 site address prefix becomes 2002:C0A8:101::/48 (Convert 192.168.1.1 to Hex which results in C0A8:0101)

We will work on the same topology we used in the previous post.