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) -- CLUE-RIPE -- Jabber: dr@cluenet.de -- dr@IRCnet -- PGP: 0xA85C8AA0