Internet Protocol Version 6 Address Space

Last Updated

2025-05-20

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.
        
  

Available Formats

XML
HTML
Plain text

Registration Procedure(s)

IETF Review

Reference

[RFC-ietf-6man-addr-assign-05]

Available Formats

CSV

IPv6 Prefix	Allocation	Reference	Notes
::/8	Reserved by IETF	[RFC3513][RFC4291]	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].
100::/8	Reserved by IETF	[RFC3513][RFC4291]	This range has been partially allocated. See [IANA registry iana-ipv6-special-registry] 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 [IANA registry ipv6-unicast-address-assignments].
4000::/3	Reserved by IETF	[RFC3513][RFC4291]	This range has been partially allocated. See [IANA registry iana-ipv6-special-registry] for details. 5f00::/8 (with 3ffe::/16, as noted at [IANA registry ipv6-unicast-address-assignments]) 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 [IANA registry iana-ipv6-special-registry] for details.
fe00::/9	Reserved by IETF	[RFC3513][RFC4291]
fe80::/10	Link-Scoped Unicast	[RFC3513][RFC4291]	See [IANA registry iana-ipv6-special-registry] 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 [IANA registry ipv6-multicast-addresses] for details.