IPv6 Address Space
Last Updated
- 2025-10-23
Note
The IPv6 address management function was formally delegated to IANA in December 1995 RFC 1881. The registration procedure was confirmed with the IETF Chair in March 2010.
As stated in RFC 3513, 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 RFC 3513 was obsoleted by RFC 4291, 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
Registration Procedure(s)
- IETF Review
Reference
- RFC 9812: Clarification of IPv6 Address Allocation Policy
Available Formats
| IPv6 Prefix | Allocation | Reference | Notes |
|---|---|---|---|
| ::/8 | Reserved by IETF | RFC 3513; RFC 4291 | 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 RFC 4291. |
| 100::/8 | Reserved by IETF | RFC 3513; RFC 4291 | This range has been partially allocated. See IPv6 Special-Purpose Address Space for details. |
| 200::/7 | Reserved by IETF | RFC 4048 | Deprecated as of December 2004 RFC 4048. Formerly an OSI NSAP-mapped prefix set RFC 4548. |
| 400::/6 | Reserved by IETF | RFC 3513; RFC 4291 | |
| 800::/5 | Reserved by IETF | RFC 3513; RFC 4291 | |
| 1000::/4 | Reserved by IETF | RFC 3513; RFC 4291 | |
| 2000::/3 | Global Unicast | RFC 3513; RFC 4291 | The IPv6 Unicast space encompasses the entire IPv6 address range with the exception of ff00::/8, per RFC 4291. 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 | RFC 3513; RFC 4291 | 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 RFC 5156. |
| 6000::/3 | Reserved by IETF | RFC 3513; RFC 4291 | |
| 8000::/3 | Reserved by IETF | RFC 3513; RFC 4291 | |
| a000::/3 | Reserved by IETF | RFC 3513; RFC 4291 | |
| c000::/3 | Reserved by IETF | RFC 3513; RFC 4291 | |
| e000::/4 | Reserved by IETF | RFC 3513; RFC 4291 | |
| f000::/5 | Reserved by IETF | RFC 3513; RFC 4291 | |
| f800::/6 | Reserved by IETF | RFC 3513; RFC 4291 | |
| fc00::/7 | Unique Local Unicast | RFC 4193 | See IPv6 Special-Purpose Address Space for details. |
| fe00::/9 | Reserved by IETF | RFC 3513; RFC 4291 | |
| fe80::/10 | Link-Scoped Unicast | RFC 3513; RFC 4291 | See IPv6 Special-Purpose Address Space for details. |
| fec0::/10 | Reserved by IETF | RFC 3879 | Deprecated by RFC 3879 in September 2004. Formerly a Site-Local scoped address prefix. |
| ff00::/8 | Multicast | RFC 3513; RFC 4291 | See IPv6 Multicast Address Space for details. |