This is absolutely the way that a client SHOULD NOT work and this is what many
OS and application developers with IETF have been trying to shoot down for
years. It is not how IPv6 works as stated one of latter e-mails.
First of all, virtually all applications ask for all entries, both v4 and v6.
After that it is practically always the configuration of the OS-level resolver
service to return what ever they are configured to. All reasonable OSs do
nowadays prefer Local addressing>NativeIPv6>NativeIPv4>TunneledIPv6. (That is
not it all I know, don’t get into that please). DNS queries are done
separately, but practically always they go to save DNS server and are returned
in the same order in a reasonable time. It is anyway hidden by the resolver, so
it actually is not relevant in this at all.
We could also talk about source address selection, but it’s hardly detail level
that we need here.
In principal already today 99,9% of the problems come from the different
tunneled v6 connections, which won’t even be used due to OS resolver
configurations explained above. So please, do not fear the DNS, it is handled
properly in “all” of the modern systems.
Second of all, the IETF has worked on e.g. something called “Happy Eyeballs”,
which could and should be implemented for abstraction layers like
Java-platforms, Qt (which actually has have it for some time already) etc, and
applications. Anyone interested may read more, but let me explain the idea:
Client launches both v6 and v4 sockets with reasonable delay to prevent
additional traffic. This is already sort of an art to define the delay, but in
principal one could favor either IPv6 or IPv4 with this. Main purpose of this
is to prevent “broken IPv6”-syndrome and simultaneously the service level
increases as there is a way around both broken IPv4(!) and IPv6. Also extensive
delays in either of the connectivity networks will be mitigated with this. So
it’s not just to promote IPv6, but to increase service level of all of the
applications! Currently the IPv6 routings mainly don’t follow IPv4 ones, which
makes this very useful.
“Happy Eyeballs” is rather fine technology and all this may be done more easily
and rudely and that’s the approach some OSs, Apps and abstraction layers do
take as well.
This all was just to state that it’s not just either or, but IPv6 MAY and
SHOULD also be used to improve service level in general. So from my point of
view, any client sticking with either IPv4 only or IPv6 only are flawed. Both
networks do have severe outages, which is not only privilege of the IPv6.
In my experience IPv6 outages are way over exaggerated, there are similar
things happening in the IPv4 all the time and there is no special buzz about it
anywhere.
--
Markku Miettinen
From: Ask Bjørn Hansen
Sent: March 13, 2013 1:12 AM
To: Darryl Ross
CC: [email protected]
Subject: Re: [Pool] Getting close to 1000 IPv6 servers
On Mar 12, 2013, at 16:48, Darryl Ross <[email protected]> wrote:
> Why would service be worse? Doesn't ntpd ask for A and AAAA records? If so,
> it'd still get the same number of IPv4 records, plus the IPv6?
Most clients will only use the AAAA records if available.
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