ipv6 source address selection

[Mikael Abrahamsson]

On Sun, 20 Oct 2013, Ole Troan wrote:

> wouldn't this be RFC6724:
>
> Rule 8: Use longest matching prefix.
>   If CommonPrefixLen(SA, D) > CommonPrefixLen(SB, D), then prefer SA.
>   Similarly, if CommonPrefixLen(SB, D) > CommonPrefixLen(SA, D), then
>   prefer SB.

The host has a bunch of /64s. I am pinging stuff outside of these /64:s. I 
am however pinging stuff in adjacent /64:s within the same /56 (or /48), 
but the host tables I can find has no information about /56 or /48s.

$ ip addrlabel list
prefix ::1/128 label 0
prefix ::/96 label 3
prefix ::ffff:0.0.0.0/96 label 4
prefix 2001::/32 label 6
prefix 2001:10::/28 label 7
prefix 2002::/16 label 2
prefix fc00::/7 label 5
prefix ::/0 label 1

I don't understand why the host would choose source address in 
2001:db8:1:1000:/64 when pinging 2001:db8:1:1001:1/128 because of this, 
but use 2001:db8:1:8000::/64 when pinging the rest of the Internet (well, 
actually my hosts are in 2a00::/16 really, but never mind, should be the 
same).

What am I missing?

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se