IPv6

Address Space

http://www.denis.lemire.name/images/wiki/ipv6-address-space.png

Allocation and Assignments

Minimum direct allocation is currently /32.

ISP assignments are as follows:

• /64 when it is known that one and only one subnet is needed.
• /56 for small sites, those expected to need only a few subnets over the next 5 years.
• /48 for larger sites

Addresses Space Size

• 340,282,366,920,938,463,463,374,607,431,768,211,456 unique IPs
• 42,535,295,865,117,307,932,921,825,928,971,026,432 IPs in 2000::/3 (1/8^th of total address space)
• 1,208,925,819,614,629,174,706,176 IPs in a /48
• 536,870,912 /32 prefixes within 2000::/3
• 65,536 /48 prefixes with a /32
• 65,536 /64 subnets within a /48
• 35,184,372,088,832 /48 prefixes within 2000::/3
• 8,192 IPv6 /48 prefixes for every IPv4 address in 2000::/3 alone.
• 18,446,744,073,709,551,616 IPs within a /64 subnet

Special Prefixes

• ::/8
  • ::/128 - Unspecified
  • ::1/128 - loopback (IPv4 127/8 equivalent)
  • ::ffff:0:0/96 - IPv4 mapped addresses
• 2000::/3 - IANA Global Unicast
  • 2001::/32 - Teredo (RFC-4380)
  • 2001:10::/28 - Orchid (RFC-4843)
  • 2002::/16 - 6to4
• FC00::/7 - unique local addresses
  • FC00::/8 is to be managed by a so-called "ULA-Central" for assigned /48s. As of 9-2007, this body has yet to be formed.
  • FD00::/8 is allocated by appending a randomly-generated 40-bit string, to derive a valid /48. RFC4193 offers a suggestion on how to do the random generation, to try to guarantee a minimum-quality result if the user does not have access to a good source of random numbers.
• FE80::/10 - link-local addresses (169.254/16 equivalent)
• FECO::/10 - site-local (deprecated)
• FF00::/8 - multicast

The remaining prefixes are all reserved for future Unicast allocations.

Multicast Addresses

Multicast addresses exist within the 'FF00::/8 prefix.

• FF02::1 - all v6 hosts on local subnet (IPv4 equivalent 224.0.0.1)
• FF02::2 - all v6 routers on local subnet (IPv4 equivalent 224.0.0.2)

Protocol Translation Mechanisms

• faithd can be used to translate on a per service basis.
• ptrtd is a similar and better solution, but only appears to run on Linux at this time.
• NAT-PT is also an option but it has been deprecated.
• Using one of the above, totd is still required to translate DNS.

MAC to EUI64

A MAC address is 48 bit wide, but we need a 64bit host ID in EUI64 format. The transformation is actually quite easy:

1. take the MAC of the network device (eg. 00:e0:81:2e:b6:d1)
2. flip bit 2 of the first byte (02:e0:81:2e:b6:d1)
3. insert FFFE in the middle (02:e0:81:FF:FE:2e:b6:d1)
4. combine with the network prefix into an IPv6 address (fe80::2e0:81FF:FE2e:b6d1)

Useful or Interesting Links

• IPv6 6to4 Reverse DNS Delegation - The Number Resource Organization
• Global IPv6 Deployment Progress Report
• SixXS IPv6 to IPv4 and IPv4 to IPv6 Website Gateway
• IPv6: An Interview with Itojun
• Generate Unique Local Address
• IPv4 Address Report
• IPv6 configuration guide for FreeBSD users

History

Date	Relevance
Mar 1996	6bone started
Jan 1, 2004	6bone prefix allocations halted.
Jul 20, 2004	Experimented with Freenet6 and Hurricane Electric tunnels
Jun 6, 2006	6bone prefix phased out (3FFE::/16)
Oct 15, 2007	IPv6 6to4 setup
Dec 17, 2007	Tera-Byte prefix (2610:78:ad::/48)
Feb 4, 2008	IPv6 records added to DNS root
July 9, 2008	GoDaddy adds support for IPv6 glue for .com/.net TLDs
Mar 12, 2008	Google Accessible via IPv6!
Jan 19, 2009	Added IPv6 glue for my name servers (inferno,frosty)