Why you shouldn't worry about IPv6 just yet

[Fred Baker]

On Aug 21, 2010, at 12:06 AM, bmanning at vacation.karoshi.com wrote:

> 		if you don't like the crusty IVI code, I've heard there is 
> 	something else outhere called AFTR? which might do the same thing.

It doesn't. It runs DS-lite.

DS-lite assumes you have an IPv6 network and enables you to tunnel your IPv4 over it. Upstream, there might be a traditional IPv4/IPv4 NAT. So it gives you native IPv6 connectivity and dual-NAT'd tunneled IPv4 connectivity. The premise is that you have a part of your network - at least one router or at least one link - that you have reconfigured as IPv6-only, and that the periphery of that ipv6-only domain is populated with some number of these things. As your IPv6-only domain grows, the distance between the tunnel endpoints grows.

The premise is that your network is, within that domain at least, primarily IPv6, but the service is primarily IPv4. The downside of it is that there always has to an an "other end" for your IPv4 service, and it has to be in a provider you trust.

In 6rd, Free.fr did the opposite. The started with their IPv4 infrastructure, and provided an application that (because they provisioned it that way) only ran on IPv6, and came up with an IPv6/IPv4 tunneled infrastructure that could provide that service. The service turns out to be popular, something akin to youtube. So they are giving you what appears to be a dual stack infrastructure, but is in fact IPv4 plus IPv6/IPv4. As they decide they want to, they can of course change to dual stack as they choose, obsoleting the tunneled bit, and when it suits them they can turn IPv4 off.

So for 6rd, the premise is that the service is applications, at least one of them runs IPv6 (which happens to run on IPv4 but can be changed to native service without the user knowing) and at least one of them runs on IPv4. unlike ds-lite, which is trying to help you build an ipv6-only infrastructure, it tries to help you build a dual stack infrastructure.

Translation, which IVI is part of, starts from the assumption that some of your systems are ipv4-only and some are ipv6-only, and they need to talk with each other. translation accomplishes that, to at least some extent.