IPv6 Address Space

IPv6 Address Space
IPv6 Address Space
2025-10-23
Note
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.
Formerly known as
Internet Protocol Version 6 Address Space (pursuant to [
IESG decision
])
Available Formats
XML
HTML
Plain text
Registration Procedure(s)
IETF Review
Reference
RFC9812
Available Formats
CSV
IPv6 Prefix
Allocation
Reference
Notes
::/8
Reserved by IETF
RFC3513
][
RFC4291
This range has been partially allocated. See [
IPv6 Special-Purpose Address Space
] for details. ::/96, formerly defined as the "IPv4-compatible IPv6 address" prefix, was deprecated by [
RFC4291
].
100::/8
Reserved by IETF
RFC3513
][
RFC4291
This range has been partially allocated. See [
IPv6 Special-Purpose Address Space
] for details.
200::/7
Reserved by IETF
RFC4048
Deprecated as of December 2004 [
RFC4048
]. Formerly an OSI NSAP-mapped prefix set [
RFC4548
].
400::/6
Reserved by IETF
RFC3513
][
RFC4291
800::/5
Reserved by IETF
RFC3513
][
RFC4291
1000::/4
Reserved by IETF
RFC3513
][
RFC4291
2000::/3
Global Unicast
RFC3513
][
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 [
IPv6 Global Unicast Address Space
].
4000::/3
Reserved by IETF
RFC3513
][
RFC4291
This range has been partially allocated. See [
IPv6 Special-Purpose Address Space
] for details. 5f00::/8 (with 3ffe::/16, as noted at [
IPv6 Global Unicast Address Space
]) was used for the 6bone, but returned [
RFC5156
].
6000::/3
Reserved by IETF
RFC3513
][
RFC4291
8000::/3
Reserved by IETF
RFC3513
][
RFC4291
a000::/3
Reserved by IETF
RFC3513
][
RFC4291
c000::/3
Reserved by IETF
RFC3513
][
RFC4291
e000::/4
Reserved by IETF
RFC3513
][
RFC4291
f000::/5
Reserved by IETF
RFC3513
][
RFC4291
f800::/6
Reserved by IETF
RFC3513
][
RFC4291
fc00::/7
Unique Local Unicast
RFC4193
See [
IPv6 Special-Purpose Address Space
] for details.
fe00::/9
Reserved by IETF
RFC3513
][
RFC4291
fe80::/10
Link-Scoped Unicast
RFC3513
][
RFC4291
See [
IPv6 Special-Purpose Address Space
] for details.
fec0::/10
Reserved by IETF
RFC3879
Deprecated by [
RFC3879
] in September 2004. Formerly a Site-Local scoped address prefix.
ff00::/8
Multicast
RFC3513
][
RFC4291
See [
IPv6 Multicast Address Space
] for details.