The exhaustion of IPv4 address space
When I interact with people from all around the world discussing IPv6, there continue to be questions about the projected lifetime for IPv4. This article presents consumption rate and lifetime projections based on publicly available Internet Assigned Numbers Authority (IANA) data. In addition, there is discussion about why the widely quoted alternative projection may be flawed, thus leading everyone to believe we have much more time than we might.
The chart in Figure 1 shows the distribution of all 256 IANA /8 allocation units in IPv4 [1] as of July 1, 2005. The Central registry represents the allocations made prior to the formation of the Regional Internet Registries (RIRs). ARIN (North America) [2], RIPE NCC (Europe) [3], APNIC (Asia/Pacific) [4], LACNIC (Latin America) [5], and AfriNIC (Africa) [6] are the organizations managing registrations for each of their respective regions. RFC 3330 [7] discusses the state of the Defined and Multicast address blocks. The Experimental block (also known as Class E—RFC 1700 [8]) was reserved, and many widely deployed IPv4 stacks considered its use to be a configuration error. The bottom bar shows the remaining useful global IPv4 pool. To be clear, when the IANA pool is exhausted there will still be space in each of the RIR pools, but by current policy [9] that space is expected to be only enough to last each RIR between 12 and 18 months.
