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

On 16-Dec-22 22:15, Pascal Thubert (pthubert) wrote:
> Hello Jen:
> 
>> So from the network perspective the prefix length does not really matter. As
>> long as your address plan allows that, there is no difference between
>> delegating /128 or /64 from the network scalability perspective.
> 
> The big if is whether the plan allows it.
> With what my SP gives me on my phone or my home gateway, I cannot plan for all my devices.
> IPv6 /32s are as scarce as IPv4 addresses, and the wrong decision now could be trouble later.
> Why force a waste everywhere when the usage is only in a few places?
> 
>> But would make a huge difference to the host. So why not?
> 
> I fail to see why /64 makes such a big difference to any host. Maybe you could explain why it makes such a difference in the hosts where you're aware it does, and then show that it is a general concern? I have trouble to see that from my own experience.
> 
> I believe the only debate is whether there's a maximum plen or whether we can go all the way to 128, and for that debate, I believe the admin should own that, not us.

Well, as others have noted or implied, the *reason* that IPv6 hosts (i.e., non-routers) are highly transportable without anything such as Mobile IPv6 (and without a requirement to support DHCPv6 at all) is because of the universal deployment of SLAAC with a fixed IID length of 64.

So while I have long argued that this particular instance of "64" should be treated architecturally as a parameter, not a constant, and that everything should be (re)designed with it as a parameter (exactly as RFC 4861/4862), we cannot possibly speak loosely either about changing it or about getting rid of SLAAC.

To be clear, Pascal, I *completely* agree with your analysis and I really want draft-thubert-6man-ipv6-over-wireless to be adopted by 6MAN, but we have to proceed very carefully indeed to avoid widespread breakage en route.

For example, delegating completely the IID length to operators, even if we got past the fact that "64" is burned into millions (probably a billion by now?) of devices, is not OK because of a minimum level of privacy concern. I'm not sure I have anything new to say on that point but we discussed it at https://www.rfc-editor.org/rfc/rfc7421.html#section-4.5 : "Thus, we can argue that subnet prefixes longer than say /80 might raise privacy concerns by making the IID guessable." That criterion (at least 48 pseudo-random bits) is quite independent of SLAAC, DHCPv6, and PD.

Regards
    Brian

> 
> All the best;
> 
> Pascal
> 
> 
> 
>> -----Original Message-----
>> From: v6ops <v6ops-bounces@ietf.org> On Behalf Of Jen Linkova
>> Sent: vendredi 16 décembre 2022 2:24
>> To: Ole Troan <otroan@employees.org>
>> Cc: V6 Ops List <v6ops@ietf.org>; xiaom@google.com; draft-collink-v6ops-
>> ent64pd@ietf.org
>> Subject: Re: [v6ops] Fwd: New Version Notification for draft-collink-v6ops-
>> ent64pd-01.txt
>>
>> On Fri, Dec 16, 2022 at 8:38 AM Ole Troan <otroan@employees.org> wrote:
>>> Possibly mocking the idea of assigning a /64 to every host.
>>
>> Not "every" actually, some of them (I assume you read Section 10).
>>
>>> Regardless the idea of assigning a prefix to a host, even a /128, means the
>> network only has a single forwarding entry per host, which is an improvement.
>>
>> So from the network perspective the prefix length does not really matter. As
>> long as your address plan allows that, there is no difference between
>> delegating /128 or /64 from the network scalability perspective.
>> But would make a huge difference to the host. So why not?
>> In my case, most of the endpoints connected to my network are hosts which are
>> using SLAAC. But some are CPEs which are getting /56 via PD.
>> Does it matter? Not much.
>>
>>>
>>> Best,
>>> Ole
>>>
>>>> On 15 Dec 2022, at 22:31, Gert Doering <gert@space.net> wrote:
>>>>
>>>> Hi,
>>>>
>>>>> On Thu, Dec 15, 2022 at 09:47:38PM +0100, Ole Troan wrote:
>>>>> And DHCP PD can of course also assign a /128 prefix to the host if
>>>>> that???s desired. :-)
>>>>
>>>> Not sure this would actually be desirable (trading multiple ND
>>>> entries to multiple host routes), but I suspect you're mocking me a
>>>> bit :-)
>>>>
>>>> Gert Doering
>>>>         -- NetMaster
>>>> --
>>>> have you enabled IPv6 on something today...?
>>>>
>>>> SpaceNet AG                      Vorstand: Sebastian v. Bomhard, Michael
>> Emmer
>>>> Joseph-Dollinger-Bogen 14        Aufsichtsratsvors.: A. Grundner-Culemann
>>>> D-80807 Muenchen                 HRB: 136055 (AG Muenchen)
>>>> Tel: +49 (0)89/32356-444         USt-IdNr.: DE813185279
>>
>>
>>
>> --
>> SY, Jen Linkova aka Furry
>>
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