Internet Assigned Numbers Authority

Internet Protocol Version 6 Address Space

Last Updated
2024-09-10
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.
        
  
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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.