The IPv6 address management function was formally delegated to IANA
in December 1995 [RFC1881]. The registration procedure was confirmed
with the IETF Chair in March 2010.
As stated in [RFC3513], IANA should limit its allocation of
IPv6-unicast address space to the range of addresses that start with
binary value 001. The rest of the global unicast address space
(approximately 85% of the IPv6 address space) is reserved for future
definition and use, and is not to be assigned by IANA at this time.
While [RFC3513] was obsoleted by [RFC4291], the guidance provided to
IANA did not change regarding the allocation of IPv6 unicast
addresses.
This range has been partially allocated. See [IANA registry iana-ipv6-special-registry] for details. ::/96, formerly defined as the "IPv4-compatible IPv6 address" prefix, was deprecated by [RFC4291].
The IPv6 Unicast space encompasses the entire IPv6 address range
with the exception of ff00::/8, per [RFC4291]. IANA unicast address
assignments are currently limited to the IPv6 unicast address
range of 2000::/3. IANA assignments from this block are registered
in [IANA registry ipv6-unicast-address-assignments].
