Re: [v6ops] I-D Action: draft-colitti-v6ops-host-addr-availability-01.txt

["Templin, Fred L" <[e-mail]>]

Hi,

> -----Original Message-----
> From: v6ops [mailto:[e-mail]] On Behalf Of Andrew ?? Yourtchenko
> Sent: Tuesday, July 28, 2015 10:03 AM
> To: Gert Doering
> Cc: IPv6 Operations
> Subject: Re: [v6ops] I-D Action: draft-colitti-v6ops-host-addr-availability-01.txt
> 
> On 7/28/15, Gert Doering <[e-mail]> wrote:
> > Hi,
> >
> > On Tue, Jul 28, 2015 at 03:58:04PM +0200, Andrew ????  Yourtchenko wrote:
> >> I did not look at it as a problem given that every mobile phone on
> >> IPv6 will already get a /64 per host, and the number of mobile phones
> >> is dramatically bigger than the number of fixed installations.
> >
> > Bigger than then number of L2 *segments*, undoubtly.
> >
> > But no way bigger than "the number of devices that could attach to
> > a L2 link" - as all these mobile phone also has wifi, so you have way
> > more devices that attach to "shared links".
> 
> I agree on the principle, though in reality it's even more complicated
> since one device can attach to more than one link, etc. -  so I think
> it's actually even worse.
> 
> >
> > Network structure is also way different - in mobile, all devices attach
> > to some sort of aggregation router (via 3G PDP tunnels etc) - while
> > in "classic" networking, you have a multitude of independent segments
> > that do not normally have aggregation infrastructure or provisioning
> > available.  Prefix mobility in a typical enterprise networks (where
> > you'd have enough devices in a L2 segment to start think about scaling)
> > isn't really there.
> >
> 
> Agreed.
> 
> 
> >> But I pulled that assumption more or less out of my thumb, based on
> >> observed anecdata, so would be happy to be proven wrong.
> >>
> >> If we say we want to absolutely avoid NAT, then something has to give,
> >> and I don't know which tradeoff is a better one, both can be argued
> >> for and against. I think we might need both.
> >
> > If you want my opinion, I think DHCPv6-PD to single hosts (= not something
> > that does tethering) is not a reasonable approach.
> 
> My line of logic was that DHCPv6-PD with a /128 prefix is not much
> different from IA_NA.

It is different, because unlike IA_NA a delegated prefix (even a /128) is not
to be assigned to the link on which the delegation was coordinated. Also,
the /128 is carried in the routing system, and may not match any on-link
prefixes at all.

Thanks - Fred
[e-mail]

> >From there it is trivial to say "no, thou shalt not do /128, use
> something shorter", and have the luxury to not define what is the
> value of "shorter" is because it's just a prefix length, and we can
> change per-situation.
> 
> Going from one IA_NA to 10 IA_NA to 30 IA_NA is much harder, so we
> will be forced to freeze on the "right" value.
> 
> >
> > If something does tethering, you need to decide what you're talking about,
> > "enterprise-ish", "mobile" or "homenet".  In mobile, DHCPv6-PD, or just
> > sharing the PDP /64.  In homenet, HNCP or DHCPv6-PD.  In the enterprise?
> > No idea what can be implemented with the typical constraints on
> > trackability, security, etc.  (like: if the device attaches to *this*
> > network, it's permitted to go *there* by IP ACLs - whether or not this
> > is a reasonable approach in itself anymore stands to be debated, but it
> > will be with us for a long time).
> 
> I think you pointed the crux of the issue here: the enterprise network.
> 
> An enterprise does not want one uncontrolled device behind another
> uncontrolled device, so realistically it will run IA_NA. And because
> it will want the cheapest possible hardware to provide the function,
> it will try to minimize the number of IA_NAs per host.
> 
> And unless the hosts will crash and burn if they can not get X IA_NAs
> upfront (they won't), this number will go down to a number providing
> the most important 90% of functionality.
> The remaining 10% will have to adapt.
> 
> --a
> 
> 
> >
> > 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
> >
> 
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