Re: [v6ops] Chair decision on WGLC for draft-ietf-v6ops-dhcp-pd-per-device-04

[David Farmer <[e-mail]>]

On Wed, Nov 1, 2023 at 12:28 PM Gert Doering <[e-mail]> wrote:

> Hi,
>
> On Wed, Nov 01, 2023 at 02:27:11PM +0000, Xipengxiao wrote:
> > In general, the draft is in good shape.  The remaining debate
> > focuses on prefix size.  The chairs would like to point out that
> > there is no need for a draft to solve all problems to pass WGLC -
> > It only needs to solve the problems in the intended scenarios and
> > make no harm in other scenarios.  This draft points out that many
> > existing hosts only support SLAAC with /64 prefixes, and in order
> > not to require changes to such hosts,  /64 or shorter prefixes must
> > be delegated.  This is a practical choice.  For other scenarios
> > where unique /64 (or shorter) prefix per client cannot be afforded,
> > people can choose not to take this approach so this draft makes no
> > harm.  With this consideration and acknowledging that it's a "rough
> > consensus", the chairs declare this draft has passed WGLC.  Thanks
> > to all the people who provided reviews and comments.
>
> I do consider this actively harmful.  It establishes a "each host gets
> a /64" as best practice, disguising as "because existing hosts do not
> know other ways" (they do not know how to do DHCPv6-PD in the first place,
> so this is a very weak statement).
>

"It establishes a practice" of a /64 per host, but the draft is not
designated a BCP. The draft is designated Informational, clearly stating
it's not applicable in all situations. So, claiming "it establishes a best
practice" seems to be a significant overstatement, at least in my opinion.


> The point of having 128 bit is not to throw half of it away.
>
> The effect of this will be endless discussions in address policy fora,
> pointing at this draft, requesting larger assignments - which is one
> of the things IPv6 set out to do away with, people receiving address
> blocks from their ISP that suddenly turn out as "too small".
>

Furthermore, from a utilization perspective, a /64 per host isn't
significantly different than 10 or even 100 hosts per /64. The number of
addresses in a /64 is so very large any reasonable number put in
the numerator is just insignificant. However, to a certain extent, the same
could be said of /80 per host, and that would allow for a reasonable number
of hosts, with a prefix for each host for a typical /56 or even a /60
residential allocation.

But, this isn't one side's fault because, at one point, the IETF did say
the shortest assignment should be /48, and ISPs argued to go with shorter
prefixes.



> Well done.
>
> Gert Doering
>         -- NetMaster
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