Saturday, October 29, 2011

Stateful and Stateless NAT64

It's very easy to deploy IPv6 for MPLSVPN service provider who uses IPv4 as transport IPv6 traffic. But in the case of mobile users or normal enterprise users, it is totally different.
In my previous post, I have mentioned traffic flow of DNS64 when IPv6 host communicates with IPv4 server. NAT64(Network Address Translation) works in either stateless or stateful mode. Both modes has its own advantages and disadvantages.

Stateless NAT64

Figure 1

In stateless NAT64, state is not preserved which means for every IPv6 user a dedicated IPv4 address is required. As we are in IPv4 depletion phase, its very difficult to adopt this mode of NAT64. The only advantage of using stateless NAT64 when you have few numbers of IPv6 addresses(NAT46). NAT64 stateless is useless because of the reasons mentioned by Ivan in his post.

Stateful NAT64
Figure 2

In stateful NAT64, states are maintained like it is happened in NAT-PT scenarios. A single IP Address is used for all the private users with different port numbers. In the above diagram, a single IPv4 address is used with different port numbers for all the users of IPv6 which are in that LAN to access a public IPv4 server.

Read the white paper stating the difference between stateless and stateful NAT64

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