Re: [v6ops] Fwd: New Version Notification for draft-collink-v6ops-ent64pd-01.txt

[Gert Doering <[e-mail]>]

Hi,

On Fri, Dec 16, 2022 at 12:18:32PM +1100, Jen Linkova wrote:
> On Fri, Dec 16, 2022 at 1:44 AM Gert Doering <[e-mail]> wrote:
> > I do not think that a /64 per host is reasonable address usage.
> 
> Well, when we assign /64 per vlan, most of those addresses are not
> used either, right?

I never said that I *like* a /64 per VLAN, but that ship has sailed 
long ago and can no longer be stopped (personally, I think it was a
blatantly stupid idea).

I strongly dislike having to assign a /56 or larger "per VLAN", just
because there might be 100s of hosts requesting a /64.  This is an 
order of magnitude different in subnet consumption - and while we
have limitless addresses in a single subnet, we do not have limitless
subnets in a typical hierarchical network deployment ("country, 
region, site, department, firewall zone, ...").

> > To implement this, network admins need not only to add v6 subnets
> > to broadcast segments but also add pools of sizeable size, which does
> > create pressure in the /48.../64 range of the addresses they have
> > ("one /48 per site").
> 
> Even 1 /48 per site gives you 65K /64s.
> Also I do not think that "one /48 per site" is set in stone. It's
> mostly because you can't assign less if you want local ISP egress -
> but nothing would prevent you from assigning more.

Good luck trying to get global RIR policies relaxed on that - there's
a reason (called "Geoff Huston math") why it was lowered from "always, 
every customer/site gets a /48" to "most will only get a /56".

> > Something like a /96 per host - so "limitless amounts of host would
> > fit into a single /64" would avoid that, and still fulfill the
> > stated necessity of having many many many addresses per hosts.
> 
> Am I right that smth like "the prefix MUST be at least /96 but SHOULD
> be /64" would make you less unhappy about the proposal?

No.  It should not even suggest that adding a /64 per host for a regular
"there could be hundreds of hosts" multiaccess network would be something
reasonable to do.

It could say "operators that have sufficient address space MAY assign
a /64 per host".

OTOH, there are no mechanisms on the hosts today to deal with "incoming
DHCPv6 PD, and address assignment to consumers on the host" - so if we
can get that right *first*, not relying on "SLAAC, so /64" for this
step, the benefit of a /64 "it can do SLAAC!!" goes away.

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

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