Introduction to IPv6 Addressing

The depleting IPv4 addresses is one of the main reasons for a new IP version, IPv6. The size of an IPv4 address is 32 bits (4-bytes). The size of IPv6 address is 128 bits (16 bytes), which is four times longer than the 32-bit IPv4 address size. The number of possible addresses in IPv4 is 232 addresses. That number is 4,294,967,296 IPv4 addresses or just above 4.29 billion IPv4 addresses.

No one expected the rise and growth of internet, as we see today, during it’s early period of development. When IPv4 addresses were allocated during the early period of internet, many organizations were allotted very large number of IPv4 addresses, which were never used. There were difficulties in reclaiming those unused IPv4 addresses back. In other words, the allocation of IPv4 addresses were not in proportion to today’s address requirement. Many organizations were allotted IPv4 addresses, more than the address requirement of a small country.

World’s human population is expected to grow to 8 billion in October, 2023. People are using multiple gadgets, computers, smart televisions, gaming devices etc., all need internet connectivity and IP addresses. Just 4.29 billion IPv4 addresses are not enough to provide all with enough IP addresses.




But in IPv6, there are 2128 (3.4x1038) addresses. That is, IPv6 has 340,282,366,920,938,463,463,374,607,431,768,211,456 number of IPv6 addresses. That is a staggering enormous number.

Such a large amount of available IPv6 addresses ensure that we will never again run out of IPv6 addresses and it also allows multiple levels of hierarchy and flexibility in designing hierarchical unicast addressing and routing.

IPv4 addresses are 32-bit binary addresses, divided into four octets (bytes). This 32-bit number is difficult to represent and use in binary format and therefore IPv4 addresses are represented in decimals, separated by a dot.

An example of IPv4 address is

However, IPv6 addresses are 128-bit numbers, which are are much larger than IPv4 addresses. Representing and using 128-bit numbers, even in decimal numbers is very difficult. Hence the IPv6 addresses are represented in hexadecimal numbers, separated by a colon (:).

An example of IPv6 address is 2001:0DB8:0000:0002:0022:2217:FF3B:118C.


Written by Jajish Thomas.
Last updated on 2nd September, 2023.


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