Re: IPv6 in Debian
On Tue, 31 Jul 2007, Andrew McMillan wrote:
> 2) many cheap routers / DSL modems / ... are broken, and
> *ignore* AAAA queries entirely, rather than returning a
> negative response.
>
> To have problems with having the IPv6 module loaded *both* these
> circumstances need to be true.
I got that problem using the recursive nameservers of big providers in
Brasil, as well as when using Debian bind as my recursive nameserver (and
thus only contacting authoritative nameservers from my machine).
It was in Sarge, but it was a PAIN. I sure hope bind is not as dumb
nowadays (it passed your dig test without problems, for whatever it is
worth).
Can we have a "enable IPV6 yes/no" question in the installer? That fixes all
problems in one go. Then tweak the system's defaults for the answer.
For those upgrading, we can add the proper information to the release notes
telling them where to mess to get a ipv6-optimized OR a ipv4-optimized
system.
> dig @192.168.1.1 AAAA andrew.mcmillan.net.nz
Wasted one extra second, here. And you bet it would blow up if something
tried to actually use THAT to connect over ipv6, since I only have ipv4 :-)
One second is a *lot* to waste on name queries. You do not even want those
to be produced, in a IPV6-less box. Note: ipv4 box asking bind on a ipv4
box, with bind configured to only deal with ipv4.
> In recent glibc installations the second problem *can* also be worked
> around by editing /etc/gai.conf to give the highest priority to IPv4
> responses. This will mean that the call to the resolver will return
> when it receives the IPv4 address, without waiting to see if a higher
> priority address may yet be received.
Now, *that* is useful information! Thanks!
> It seems to me that the patch Tolleff has written should remove that
> inconvenience, so the effects of problem #2 will become invisible
> (except to the poor people in such situations who try and actually use
> IPv6 :-)
Not completely, you still get extra name resolver delay unless you fix the
resolver to prefer IPv4 (and maybe even then -- I didn't test). That also
needs either to be documented, or to be enabled by default.
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh
Reply to: