Re: [v6ops] Fwd: I-D Action: draft-ietf-v6ops-unique-ipv6-prefix-per-host-07.txt

[Mark Smith <[e-mail]>]

On 4 August 2017 at 11:53, DY Kim <[e-mail]> wrote:
> In the 2nd para of Sec. 4, it reads:
>
> “… a Unique IPv6 prefix (currently a /64 prefix)…”
>
> Assuming that there’d be at some place upwards where a /48 prefix would be
> present, which prefix length is up to a common practice for ISPs in
> assigning a prefix to a site, does the above spec means:
>
> o the maximum number of devices that the proposed scenario can accommodate
> is 64K (2**16; 64 - 48 = 16)?
>

(Not speaking on the authors behalf)

If you only received a /48 for your site, then yes, that would be the
upper limit on how many devices this method supported.

However, the scenario being described is one of a service provider,
and they will get at least a /32 from their RIR, meaning in theory the
maximum number of hosts they can support is 4 billion (!). They could
get larger than /32 if they needed to if it became too small.

In this scenario a "site" is really the individual host, rather than a
boundary of a group of subnets at a site. /48 or /56 are common
aggregation boundaries for a multi-subnet site, so they don't really
apply here. The service provider could internally aggregate the /64s
at any where they need to between e.g. /32 and /63 to suit their
routing protocol scaling.

So in short, /48 is not constraining this solution because /48 doesn't apply.

Regards,
Mark.