IPv6 is handed out using sparse allocation inside /12 from IANA ensuring two goals: minimal recall on IANA and maximum utilisation inside each /12 preserving second call headroom for the original delegates announcing the space in BGP. They can take a /32 to a 31 or 30 or 26 or whatever and not have to announce disaggregated blocks in BGP. (They can disaggregate, but it's not forced by being given discontinuous blocks) The sparse model is like binary chop: it tends to equalise the size of the "hole" across all delegations. It's a reservation system without having to make reservations: within limits everyone who hasn't yet requested subsequent space can request it, and everyone within reason has the same growth potential to market against other delegates of the same size at that point in time.
APNIC runs modified sparse: the /12 is divided up into pools and bigger and smaller parts are used to make two sets of binary chop headroom reflecting the scale.
The outcome should be visible in the chart: a grey peppering of blocks spread throughout the /12s and for APNIC evidence of at least two densities of scatter.
Broadly speaking, it's worked. The RIR collectively haven't gone back to IANA very often, a lot of IPv6 space remains. Scarcity isn't driving the dynamics of BGP announcement and disaggregation. Compare that to IPv4, costs of entry to market for new players, avg number of prefixes and relative disaggregation of holdings.
As an example of how big ipv6 is, we got a /29 from ripe at a not very big at all ISP, which even if we had handed out a /48 to each and every DIA customer physical location/cpe, would have lasted us at our projected growth rate for the next several hundred years.
And that was in addition to the ARIN /32 we already had.
APNIC runs modified sparse: the /12 is divided up into pools and bigger and smaller parts are used to make two sets of binary chop headroom reflecting the scale.
The outcome should be visible in the chart: a grey peppering of blocks spread throughout the /12s and for APNIC evidence of at least two densities of scatter.
Broadly speaking, it's worked. The RIR collectively haven't gone back to IANA very often, a lot of IPv6 space remains. Scarcity isn't driving the dynamics of BGP announcement and disaggregation. Compare that to IPv4, costs of entry to market for new players, avg number of prefixes and relative disaggregation of holdings.
(Disclaimer: work in an RIR)