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Re: about the coexistance scenarios in draft-ietf-v6ops-nat64-pb-statement-req-01



On 28 jul 2008, at 7:52, <teemu.savolainen@nokia.com> <teemu.savolainen@nokia.com > wrote:

The situation we want to reach is where hosts can have just
IPv6 connectivity and still be fully functional.

Assuming all applications are supporting IPv6, or also including cases
where host may be running IPv4-only apps?

Well obviously we don't want to support IPv4-only apps until the end of time.

But we will have to in the short term.

What I'm wondering is that if a translation solution is designed to
assume fully IPv6-capable host (including all random third party
softwares), then it might be less usable in near future than tunneling
based solutions.

If the host knows the prefix for the translator, it can easily internally make IPv4 API calls create IPv6 packets that will be translated to IPv4 by the remote translator. One approach is to simply create IPv4 packets and encapsulate those in IPv6, but the extra IPv4 header provides no actual functionality so we can probably optimize it away without too much trouble. So the NAT464 translation scenario and the dual stack light scenario are pretty much the same thing.

In the case of a CPE handling internal hosts that actually create IPv4 packets the tradeoff between encapsulation and translation may be somewhat different.

for what purpose it would need
translation services? For IPv6-only applications? I would assume it
takes quite a while before all applications are IPv6-capable, and that
all devices behind a host (such as gaming consoles etc) are also
IPv6-capable.

Don't forget that higher level APIs hide the differences between IPv4 and IPv6, so very many applications can work over IPv6 without having specifically be designed to do so.

Or can we assume applications to be IPv6-capable in timeframe operator
would be interested to provide IPv6-only connectivity?

I'm not familiar with cellular operations, but I would assume that running IPv4 and IPv6 over the cellular network concurrently is far from ideal, just providing IPv6 and then use an IP layer mechanism to let the applications talk to the IP world would be helpful.

Or should a host internally implement v4->v6 translation, thus making a
host look like fully IPv6-capable towards network?

I think in many cases that makes sense, yes.