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

[Gert Doering <[e-mail]>]

Hi,

On Mon, Aug 07, 2017 at 12:35:25PM +0200, JORDI PALET MARTINEZ wrote:
> Most of the RIR policies allow a shorter prefix than /48 for a single site 
> if justified. 

"If justified" has traditionally been along the lines of "number of buildings,
number of subnets, number of aggregation levels", so, number of *networks*.

"Number of hosts" has not been a justification argument in (at least)
RIPE IPv6 policy, so that would be a fairly significant change.

Personally, I would be very careful here - permitting assignments of 
larger address blocks because we *waste* a /64 on a potentially very 
large number of hosts in a network might cause shortage further up.

And yes, I think this is extremely wastive, well over the limits of what
is normal "do not care about wasting addresses!" level of IPv6 normal.

On a subnet, having a "it is big enough for everything, no matter how
many hosts" is a desirable property because it makes network planning much
easier - single size fits all, focus on more interesting work.  A /64
is already excessive here, but given that the number of subnets is
bound by factors like "how many different purposes can you come up
with?", "router config", etc.  I'm willing to accept a /64 here.

A /64 per *host* is much less bound - while far beyond anything you can
configure on that host, so the trade-off "waste vs. useful number of bits"
is not reasonable for me.


Should this topic come up in RIPE policy discussion, I'll chair the
discussion and refrain from having an opinion, but will reserve the right 
for a "told you so" later.

Gert Doering
        -- RIPE APWG chair
-- 
have you enabled IPv6 on something today...?

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