Re: Anybody Using IPv6?

On 2025-05-20 23:14, Marc Haber wrote:

"Carlos E. R." <robin_listas@es.invalid> wrote:

On 2025-05-20 19:43, Marc Haber wrote:

What does the IPv6 routing table of the system in question say?

>
I don't have a problem with the laptop currently. The problem was some
years ago, on several computers.
>
cer@Isengard:~> ip route
default via 192.168.1.1 dev eth0
192.168.0.0/16 dev eth0 proto kernel scope link src 192.168.1.16
cer@Isengard:~>

 That is not the IPv6 routing table.

That is all there is.

 

So applications thought that IPv6 was available.

>
Tries to use it, gets a host unreachable, SHOULD¹ try again with the
next IP address associated with the target hostname, which might
happen to be IPv4, tries to use it, connects successfully.
>
Different behavior is a bug.
>
¹ in the RFC2119 sense

>
The gai change makes things go faster, by not trying IPv6 first.

 On a slow machine, about a millisecond, yes. That matters in high
performance computing, where professionals do the administration. It
does absolutely not matter on a personal workstation that spends 99 %
of its CPU cycles waiting for keystrokes anyway.

It is the network speed that matters, which is much slower.
--
Cheers,
        Carlos E.R.