[address-policy-wg] 2011-04 New Policy Proposal (Extension of the Minimum Size for IPv6 Initial Allocation)

On Wed, Oct 26, 2011 at 03:44:46PM +0200, Michael Adams wrote:
> But we want to do native v6 and we need additional bits to make the
> v6 pools on our access routers big enough for all our residential customers
> from the beginning.

I feel your pain, I share it totally.

Even if the first alloc will be sufficient - we all would get problems
with HD-ratio later. I was recently told that IPRAs are supposed to
judge initial alloc requests on a 2-3 year outlook, max, ONLY. Not 5-10yrs
or so as it SHOULD be to make any real sense.

So, you request a "larger than /32" block for 2-3 yrs numbers and then
have a problem to get more later:

To make the addressing plan "nice and scalable", and be done with
"single prefix pool per aggregation router, period", one really needs quite
some bits. Simple example, with two levels of hierarchy (site,
aggregation router within a site):

up to 128 aggregation sites => 7 bits
up to 16 aggregation routers per site => 4 bits
up to 65k subscribers per aggregation router => 16 bits
/56 per subscriber (DHCP-PD)

Those are absolutely realistic numbers (note the "up to"!) for a 5-10yr
outlook for certain outfits.

Sum: 56-16-4-7 => /29, nice and shiny "one size fits all" approach.

But hell opens up widely when site 129 gets built. Then, you'll better
have already more than 43.67 million customers, otherwise you won't
get your additional bit for sites 129-256.

Raising the HD-ratio so much (from 0.8 to 0.94) was a clear mistake
in my opinion. Even if you have every(!) german citizen as customer,
you would never qualify for more than a /28. That's ridiculous.

The 128 bit IPv6 addr width had the promise to provide enough bits for
internal hierarchy for "nice" (read: cheap to manage, easy to deal with in
general and specifically operations) addressing plans. For large/mid-scale
residential ISPs of certain topologies and access infrastructures, the
current "ruleset" of "consider only 2-3yrs plans for initial alloc"
in combination with HD-ratio 0.94 requirement for getting more bits, is
a real problem. We're back to slice-and-dice-on-demand - no proper
hierarchical structure anymore. Otherwise, HD-ratio 0.94 WILL bite
sooner or later.

Best regards,
Daniel (pulling teeth on an addressing concept but having no joy)

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