It is also becoming apparent that:
- the "core internet" (ie the web and any infrastructure server) will take a long time to move to v6 and/or dual stack.
- new v6-only edges will have to communicate with it. So we need v6->v4 translation in the core
Some companies have implemented MPLS in the core, therefore they can easily add IPv6 services by configuring 6PE on a couple of PE routers in each PoP. Beyond the PoP, in the customer's network, they can do pure IPv6 if that is what they want.
- legacy v4 PCs (think win95 up to win XP) using RFC1918 addresses behind a home gateway will never be able to upgrade to an IPv6-only environment. So if we provision the home gateway with v6-only (because there will be a point where we do not have any global v4 addresses left for it) those legacy PCs are going to need a double translation, v4->v6 in the home gateway and then v6 back to v4 in the core.
Not if they use an application layer proxy in their gateway. It's not too late to specify this as a standard function for an IPv6 Internet gateway device. Also, the "v6 back to v4" conversion could be handled in an information provider's data center (Google, CNN) not in the core.
So, no, NAT v4->v6 or v6-v4 does not solve world hunger but solve very real operational problems.
Agreed. Just about every possible transition technique will solve real operational problems and we should not be purists about this. Whether the IETF has a specification for it or not, people will build and deploy NAT and ALGs among other things. In addition, this transition comes at a time when we have the technology that allows virtually anyone (high school kids) to build some kind of network functionality on top of Linux or BSD. If that is useful, anyone can freely implement this including the manufacturers of Internet gateway devices who often use Linux or BSD as the foundation of their boxes. Back in 1994 we started to see exponential growth of the Internet because the barrier to entry suddenly became much lower. It was financially feasible to buy a bunch of modems, terminal server, Bay or Cisco routers and a bunch of Linux/BSD servers. The technology was available cheap enough to encourage many people to take the business risk. In the interim, technology has advanced somewhat and I expect to see a flurry of devices as soon as IPv4 exhaustion reaches the general press. --Michael Dillon