Re: [v6ops] PI [ULA draft revision #2 Regarding isolated networks]

[Gert Doering <[e-mail]>]

Hi,

On Sun, Jun 01, 2014 at 10:10:10PM -0400, Ted Lemon wrote:
> On Jun 1, 2014, at 9:59 PM, joel jaeggli <[e-mail]> wrote:
> > Ted I think you need rethink what you're claiming. for one rfc 6555
> > makes no claims about ipv6 address selection between multiple addresses.
> > it in fact sets aside the issue of having more than the two address
> > familes to chose from. I daresay if you have six v6 routes you probably
> > don't want to make six requests and see which one is fastest as a
> > general rule.
> 
> How is this different than doing happy eyeballs between v4 and v6?   Is it different because you're sextuply multi-homed?   I agree that that begins to look a bit problematic, but the more usual two-provider case is pretty much the same as regular happy eyeballs.

Actually, implementation-wise, there is a huge difference between

 source A       ---> talk to destination X, Y
 source A, B    ---> talk to destination Z

and it's time the IETF provides some answers how to handle the second case
(which HE doesn't talk about, and even ietf-mif-happy-eyeballs-extension
only addresses for the specific case where A and B are not on the same
interface).

6724 will not help very much in the second case - it will ensure that
"one of the GUAs" is used, but due to lack of further rules, will fall
through to the "most bits match" rule - which is only the "best" path
for some limited cases, like "talk to other hosts direclty in the A/B /32".

Worse, if you pick source A and that does not work because ISP A has 
an issue, no getaddrinfo() / HE implementation will fall back to try 
source B  (supposedly MacOS does, but I haven't verified that yet), as
the whole topic of source address probing / source address failover is
completely underspecified yet.  As in "it's complicated, leave us alone
with that stuff".

(But I'm sure we can do a lengthy discussion whether this could be solved
with RA or DHCPv6 options)

Gert Doering
        -- NetMaster
-- 
have you enabled IPv6 on something today...?

SpaceNet AG                        Vorstand: Sebastian v. Bomhard
Joseph-Dollinger-Bogen 14          Aufsichtsratsvors.: A. Grundner-Culemann
D-80807 Muenchen                   HRB: 136055 (AG Muenchen)
Tel: [phone]           USt-IdNr.: DE813185279