6to4 Address - 2002::/16

6to4 is a special type of address used with the 6to4 tunneling protocol to provide automatic address assignment for an IPv6 host to communicate with another IPv6 enabled host over the current IPv4 internet.

6to4 address gives us the ability to assign globally routable IPv6 address without the need to connect to te IPv6 internet or to register & request a block of IPv6 addresses.  Each 6to4 ip address is guaranteed to be unique since it is formed by the publicly assign IPv4 address.

6to4 address uses the global address prefix that takes the form of 2002:wwxx:yyzz::/48 where the wwxx:yyzz part is public IPv4 address assigned to a router of an organization in colon-hexadecimal format.

Here's a format of a 6to4 address:

• 16 bitsPrefix
• 32 bitswwxx:yyzz
• 16 bitsSubnet
• 64 bitsInterface ID

• 2002
• 0C9B:A665
• 0001
• 0000:0000:0C9B:A665

• 6o4 Address
• Teredo Address

Click on this link to examine this 6to4 address using the Advanced Online IPv6 Subnet Calculator: 2002:0C9B:A665:0001:0000:0000:0C9B:A665