The IPv6 address size is 128 bits. IPv6 addresses are represented in hexadecimals. The 128-bit address is divided in to 16-bits, and each 16-bit block is converted to a 4-digit hexadecimal number and separated by colons. This type of representation is called colon hexadecimal. The format of IPv6 address is xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx where each x is a hexadecimal digit representing 4 bits or a nibble. IPv6 addresses range from 0000:0000:0000:0000:0000:0000:0000:0000 to ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff.
An IPv6 address can be simplified by the following two methods.
• Omit leading zeros: Omit the leading zeros in any 16-bits. For example, IPv6 address 2001:0DB8:0000:0000:0022:F376:FF3B:AC99 may be written as 2001:DB8:0:0:22:F376:FF3B:AC99.
• Double colon: Use double colons (::) in place of a series of zeros. For example, The above address can be further simplified as 2001:DB8::22:F376:FF3B:AC99.