Internet Assigned Numbers Authority

Internet Protocol Version 6 Address Space

Last Updated
2019-09-13
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
0000::/8 Reserved by IETF [RFC3513][RFC4291] [1] [2] [3] [4] [5] [6]
0100::/8 Reserved by IETF [RFC3513][RFC4291] 0100::/64 reserved for Discard-Only Address Block [RFC6666]. Complete registration details are found in [IANA registry iana-ipv6-special-registry].
0200::/7 Reserved by IETF [RFC4048] Deprecated as of December 2004 [RFC4048]. Formerly an OSI NSAP-mapped prefix set [RFC4548].
0400::/6 Reserved by IETF [RFC3513][RFC4291]
0800::/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]. [7] [8] [9] [10] [11] [12] [13] [14] [15]
4000::/3 Reserved by IETF [RFC3513][RFC4291]
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] For complete registration details, see [IANA registry iana-ipv6-special-registry].
fe00::/9 Reserved by IETF [RFC3513][RFC4291]
fe80::/10 Link-Scoped Unicast [RFC3513][RFC4291] Reserved by protocol. For authoritative registration, see [IANA registry iana-ipv6-special-registry].
fec0::/10 Reserved by IETF [RFC3879] Deprecated by [RFC3879] in September 2004. Formerly a Site-Local scoped address prefix.
ff00::/8 Multicast [RFC3513][RFC4291] IANA assignments from this block are registered in [IANA registry ipv6-multicast-addresses].

Footnotes

[1]
::1/128 reserved for Loopback Address [RFC4291]. 
Reserved by protocol. For authoritative registration, see [IANA registry iana-ipv6-special-registry].
[2]
::/128 reserved for Unspecified Address [RFC4291]. 
Reserved by protocol. For authoritative registration, see [IANA registry iana-ipv6-special-registry].
[3]
::ffff:0:0/96 reserved for IPv4-mapped Address [RFC4291]. 
Reserved by protocol. For authoritative registration, see [IANA registry iana-ipv6-special-registry].
[4]
0::/96 deprecated by [RFC4291]. Formerly defined as the "IPv4-compatible IPv6 address" prefix.
[5]
The "Well Known Prefix" 64:ff9b::/96 is used in an algorithmic mapping between IPv4 to IPv6 addresses [RFC6052].
[6]
64:ff9b:1::/48 reserved for Local-Use IPv4/IPv6 Translation [RFC8215].
[7]
2001:0::/23 reserved for IETF Protocol Assignments [RFC2928]. 
For complete registration details, see [IANA registry iana-ipv6-special-registry].
[8]
2001:0::/32 reserved for TEREDO [RFC4380]. 
For complete registration details, see [IANA registry iana-ipv6-special-registry].
[9]
2001:2::/48 reserved for Benchmarking [RFC5180][RFC Errata 1752]. 
For complete registration details, see [IANA registry iana-ipv6-special-registry].
[10]
2001:3::/32 reserved for AMT [RFC7450]. 
For complete registration details, see [IANA registry iana-ipv6-special-registry].
[11]
2001:4:112::/48 reserved for AS112-v6 [RFC7535]. 
For complete registration details, see [IANA registry iana-ipv6-special-registry].
[12]
2001:10::/28 deprecated (formerly ORCHID) [RFC4843]. 
For complete registration details, see [IANA registry iana-ipv6-special-registry].
[13]
2001:20::/28 reserved for ORCHIDv2 [RFC7343].
For complete registration details, see [IANA registry iana-ipv6-special-registry].
[14]
2001:db8::/32 reserved for Documentation [RFC3849]. 
For complete registration details, see [IANA registry iana-ipv6-special-registry].
[15]
2002::/16 reserved for 6to4 [RFC3056]. 
For complete registration details, see [IANA registry iana-ipv6-special-registry].