IPv6 Protocol

Internet Protocol Version 6 (IPv6) is the latest version of the Internet Protocol (IP). It is intended to replace IPv4, which still holds the majority of Internet traffic. IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4 address exhaustion.

An IPv6 address consists of 16 bytes (octets); it is 128 bits long. IPv6 addresses consist of eight groups of four hexadecimal digits separated by colons,

for example 2221:0ac8:0ba3:0002:10b0:7a2e:0450:0032

The address space therefore has 2¹²⁸ or approximately 3.4×10³⁸ addresses

The IP address, is very long and many of the digits are zeros, we choose abbreviated form of  IPv6 addresses to represent easily. That is the leading zeros of a section can be omitted. Only the leading zeros can be dropped, not the trailing zeros.

For example,

Original IP address       ABcd:0063:0000:0000:0000:ad34:0000:a006

Abbreviated form          Abcd:63::ad34:0:a006  

An IPv6 address may be abbreviated by using one or more of the following rules:

1.     Remove one or more leading zeroes from one or more groups of hexadecimal digits

2.     Omit one or more consecutive sections of zeroes, using a double colon (::) to denote the omitted sections. The double colon may only be used once in any given address, as the address would be indeterminate if the double colon was used multiple times.

Expand the address 0:18::2:14:1418 to its original.

We first need to align the left side of the double colon to the left of the original pattern and the right side of the double colon to the right of the original pattern to find now many 0s we need to replace the double colon.

xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx

0      :    18:                                 2: 14   :1418

This means that the original address is

0000:0018:0000:0000:0000:0002 :0014:1418

If an IPv6 address is prefixing with 11111111 then it represent a Multicast addresses.

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