IPv6 and IPv6 Addresses

IPv6 Interface ID with EUI64 Format

What is an IPv6 Address?

IPv6 Address is the new generation IP address that is mainly deveoped to overcome IPv4 exhaust and its limitations. As you know, IPv4 Addresses were limited and exhaused shortly. For the new technologies, more IP addresess needed and for this need a new IP version has developed. This is IPv6. We can say that, IPv6 is the new IP Address type that we will use on our network devices anymore.


Like IPv4, IPv6 has also different IPv6 Address Types. We will talk about these address tpes one by one in another lesson detailly. Here, we will focus to the basics of the lesson. After this lesson you can also learn IPv6 Subnetting. You can also check wiki definion of IPv6.


IPv4 is most widespread implementation of IP protocol. It has 32 bit adress space, so it allow to use almost 232=4,294,967,296 addresses in internet. Because of the fact that these addresses has run out a new version of IP is revealed. With this new IP version, more addresses are available especially mentioned as almost unlimited.


Before IPv4 addresses run out, some techniques like CIDR,NAT,Priviate Addresses are used to alleviate this shortage.


Between IPv4 and IPv6, in the middle, there is another version of IP, IPv5. IPv5 is used for “Internet Streaming Protocol” for research and development. So, the new version of IP, that will be used on the network devices become IP version 6, IPv6.



The new and the next generation version of IP, IPv6 has 128 bit address space.So there are almost 2128 available addresses for this devices.This is almost 340 undecilion available addresses, nearly unlimited.


You can also test your IPv6 Knowledge on IPv6 Questions Page.


There are some new featured that IPv6 Brings. These new benefits that comes with IPv6 are given below:


  • Increased address space
  • Simplified configuration (with auto configuration)
  • Integrated security (IPSec)
  • Backward compatibility with IPv4



IPv6 Address Example

As you remember, IPv4 addresses are written with Decimal numbers. Different than IPv4, IPv6 are written with hexadecimal digits. This address is consist of eight colons and in each colons there are four digits.So the address become 8*4*4bit = 128 bit. An example of an address is given below:




There are some abbreviations that are used while using an IPv6 address. These abbreviations are mentioned below with related IPv6 examples:



  • There is no need to write the leaing zeros in an address. Leading zeros can be dropped like below:

2345:0425:2CA1:0000:0000:0567:5673:23b5 ==> 2345:425:2CA1:0000:0000:567:5673:23b5



  • If we have an entire field of zeros in ana adderss, we can use only one 0 for each colon:

2345:0425:2CA1:0000:0000:0567:5673:23b5 ==> 2345:0425:2CA1:0:0:0567:5673:23b5



  • If we have a set of contiguous zero fields in the address, we can use double colons(::). Double colon can be used only one time in an IPv6 Address Example.

2345:0425:2CA1:0000:0000:0567:5673:23b5 ==> 2345:0425:2CA1::0567:5673:23b5



IPv6 and CIDR


IPv6 Address always use CIDR (Classless Inter Domain Routing) to determine the IPv6 Prefix. You can find an example of an Ipv6 Prefix below:




IPv6 EUI-64 Format

IPv6 unicasts generally allocate the first 64 bits of the address to identify the prefix and the remainning 64 bits are identify the host portion.This interface ID is based on the interface’s hardware address.This interface ID can be produced by EUI-64 format for IPv6 Link Local Address.


To sum up Interface ID Creation with EUI-64 Format assume that we have a MAC address of 1111.2222.3333. Follow the steps in the below picture to produce an IPv6 Interface ID from this MAC address:



This EUI-65 Format is used for IPv6 Link Local Address Auto Address Configuration. There are various IPv6 Address Types. We will talk about these IPv6 Types and other IPv6 Examples in another lesson detailly. If you would like to learn IPv6 details, follow the other lessons.


You can also test your IPv6 Knowledge on IPv6 Questions Page.

Lesson tags: IPv6, ip addressing
Back to: IPv6 Course > IPv6 Addressing Overview

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