Subject: Re: Usability enhancement for IP6
To: Bryan Phillippe <>
From: Manuel Bouyer <>
List: tech-net
Date: 02/06/2005 13:01:58
On Sat, Feb 05, 2005 at 11:06:39AM -0800, Bryan Phillippe wrote:
> Hello,
> Ever since I configured a private IPv6 network with NetBSD, I've had the
> annoying problem of having to wait for multiple failed retransmits to
> public sites such as, before falling down to IPv4.  Other
> IPv6 stacks, such as Microsoft, do not have this problem.
> The following small patch fixes the problem for me: IPv6 connections to
> other private IPv6 hosts work fine and IPv6 connections to unreachable
> public IPv6 hosts fail immediately and fall back to IPv4.
> It could probably use some cleanup, and perhaps making it configurable via
> sysctl (or make it dependent on net.inet6.ip6.v6only) would be better.

I'm not even sure we need a sysctl for this. This behavior for connection
setup makes sense (for course, not for already-established connections).

Manuel Bouyer <>
     NetBSD: 26 ans d'experience feront toujours la difference