This is another obviously bogus so-called "show-stopper" (compare to the request of waiting for root DNS servers to be dual-stack; another unnecessity).
None of this is bogus. Running dual-stack has almost no advantages over
running IPv4-only,
I don't think this is correct. It gives you v6 for services which would only be available (or working correctly) using v6.
Since there are no services that are inherently only possible over IPv6, the existence of services that are only available over IPv6 means that someone is running (effectively) IPv6-only. If they were fully dual-stack then the service would also be available over IPv4. So usefulness of IPv6 == usefulness of IPv6-only.
One could imagine a large number of p2p or similar applications falling under that category. Remember, our goal is not to deploy IPv6 so that we could surf the web using v6...
Our goal also isn't running IPv6 + IPv4 w/NAT for all eternity. Building an IPv6-only network is a much more attractive proposition than building an IPv4+IPv6 network, as this way there is no need to worry about lots of pesky IPv4 details (the users may have different opinions, but I'm talking about building the network right now). In a large network, having to run IPv4 everywhere just for the DNS is NOT cool, as this means having DHCP servers, worrying about subnet sizes and everything else. In an environment where the set of applications is limited (I for one only need SSH and HTTP 98% of the time) running v6-only internally and use proxying to talk to the v4 world is rapidly becoming an interesting option.
You've probably seent his already, but have a peek at:
http://www.cs.utk.edu/~moore/opinions/ipv6/dubious-assumptions.html
I'd be happy to swap IPv6 deployment scenarios some time, and mine are slightly different than Keith's. But it's not all that relevant. In order to be really useful, IPv6 needs to be able to function regardless of the IPv4 status du jour. Example: a couple of RIPE meetings ago they had lots of troubles with the DHCP server. Now I was happily logged in to my server over SSH and tunneling email back and forth, but I was completely unable to access any web pages, even the ones on my own box, because I couldn't access the DNS: I had no IPv4 address, and MacOS didn't support DNS transport over IPv6 at that time. Now if I can run into this kind of trouble without actively looking for it, how are the chances that something similar will happen at times to the ontold millions whom IPv6 will be bestowed upon in the future?
it is imperative that we make it possible to run IPv6-only, as this is the ultimate goal. Implementations that require IPv4 for critical functions, even if it's only for a small set of such functions, are useless in the long run.
Depends on how long run that will be. If you expect a node to be deployed for 10 years, probably yes. If it gets replaced or upgraded in 3 years, there's little chance of IPv4 going away during that time.
It's not a question of going away. And how many people are still running Windows 98? Or even 95 for that matter? Old stuff just doesn't go away.
And just because we update a spec doesn't mean people get to have implementations that conform to the new version any time soon, so we have to get it right from the start if at all possible.
Which is why we should not give people panic attacks about this, but look at it rationally and carefully. Get it right.
No panic attacks, but solid specifications so that people who implement them don't have to come back in a few years to update their stuff for issues that we are aware of *now*.
There will be no IETF last call as this is going for Informational, so if you really think the text is unjustified (given above), please state it now (and if possible, suggest alternative that would be more in line with the earlier context..)
I suggested:
Note that in the absense of DNS resolvers reachable over IPv6, either due to failed discovery and/or lack of configuration, DNS resolvers reachable over IPv4 may be used, if available.
Is there anything wrong with this? I think this captures what we want implementors to do fairly well. We want them to implement whatever DNS discovery we come up with, but if they don't they should at least make it possible to configure IPv6 addresses for DNS resolvers manually. However, if (they didn't implement the discovery mechanism or no IPv6 resolvers were found) and no IPv6 resolvers were configured, IPv4 resolvers can be used.
. dnsop resources:_____________________________________________________ web user interface: http://darkwing.uoregon.edu/~llynch/dnsop.html mhonarc archive: http://darkwing.uoregon.edu/~llynch/dnsop/index.html
