Re: [homenet] Let's make in-home ULA presence a MUST !?

[Mark Andrews <[e-mail]>]

In message <CAKD1Yr2aLTjEo=7yj+=[e-mail]>, Lorenzo Colitti write
s:
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> On Thu, Oct 16, 2014 at 8:26 AM, Mark Andrews <[e-mail]> wrote:
> 
> > Unless you have really old stacks your device will pick the new GUA first to
> > talk to your jukebox when you are on your neighbor's network and the ULA
> > to talk to it when you are on your own.
> >
> 
> No, it won't. It will pick GUA->GUA both times.

Actually it depends on which address has the longest match.  With
old stacks they are both treats as GUA.  ULA has at least 8 bits
in common but may have up to 47 bits in common.  The GUA is likely
to have 16+ bits in common.  There is no guarentee that the old
pair of addresses have been flushed to only leave the GUA.

> Per the table in http://tools.ietf.org/html/rfc6724#section-2.1 it will
> pick the GUA as a destination address, and per Rule 6, it will choose the
> GUA to connect to it.
> 
> Which means that if you *want* to force it to use ULA inside the network
> and GUA outside, the only scalable option is to use split-tunnel DNS. You
> could change the policy table too, but most users won't, unless the
> standards change, and major OSes change the policy tables.
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
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