Re: kern/44943: 2002::/16 (6to4) addresses are preferred over native IPv6 transport

[George Michaelson <ggm%pobox.com@localhost>]

Ahem.

I believe there is an RFC, or draft RFC expectation that tunnelled IP is 
de-preferenced to native when both exist.

So, NetBSD may not have that logic in kernel, but the RFCs specify that 
if a longest-match rule is used, with weightings, you should be able to 
avoid using 2002::/16 source IPs except when you have a working binding, 
and are sending packets to a 2002::/16 destination address.

I don't have the docs to hand, but skimming discussion on IETF v6 working 
groups leads me to believe there is a pretty clear understanding you 
shouldn't preference a 6to4 route if you have native V6.

Is that kind of route preference ordering not something we would want in 
NetBSD? Is there any way to weight preference in routes other than 
longest match? If its longest match, then the order you apply route 
statements might influence route preference, but there is this niggle in 
my mind about INADDR_ANY and what source IP selection you wind up with..

(reading http://www.ietf.org/rfc/rfc5014.txt makes me think Erik Nordmark 
coded some of this in the socket() preferences section)

-G