Dear Nick,
It would be instructive to hear from the RIPE NCC how much address space is voluntarily handed back by LIRs and other IPv4 address holders right now. Would it be possible for someone from the NCC provide a rough estimate of this?
In raw numbers, the amount of address space returned to the RIPE NCC for the past few years is as follows: 2004 587776 /13,/17,/18,/19,/20,/21 2005 1419264 /12,/14,/16,/17,/19,/21 2006 1155072 /12,/16,/17,/19 2007 2166784 /11,/16,/20 2008 1136640 /12,/16,/18,/20,/21 (year to date) Note that these are the total amount of addresses returned to the RIPE NCC. As is often the case with IPv4 allocation statistics, the numbers tend to be dominated by a small number of very large allocations, for example: In 2007 a /14 allocation was returned by an LIR when they requested a /13, in 2006 also a /14 was returned as a /13 was requested and in 2005 a /13 was swapped for a /12 this way. Also included in these numbers are the addresses reclaimed from closed LIRs: 2005 385024 /14,/16,/17,/18,/19 2006 393216 /14,/15 2007 1585152 /12,/13,/19,/20 2008 1042432 /13,/14,/15,/16,/17,/18,/19,/21 (to end of September) Please let us know if you have any further questions regarding these numbers. Best regards, Alex Le Heux RIPE NCC Registration Services