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IPv6 Tutorial

June 24th, 2011 Go to comments

Internet has been growing extremely fast so the IPv4 addresses are quickly approaching complete depletion. Although many organizations already use Network Address Translators (NATs) to map multiple private address spaces to a single public IP address but they have to face with other problems from NAT (the use of the same private address, security…). Moreover, many other devices than PC & laptop are requiring an IP address to go to the Internet. To solve these problems in long-term, a new version of the IP protocol – version 6 (IPv6) was created and developed.

IPv6 was created by the Internet Engineering Task Force (IETF), a standards body, as a replacement to IPv4 in 1998. So what happened with IPv5? IP Version 5 was defined for experimental reasons and never was deployed.

While IPv4 uses 32 bits to address the IP (provides approximately 232 = 4,294,967,296 unique addresses – but in fact about 3.7 billion addresses are assignable because the IPv4 addressing system separates the addresses into classes and reserves addresses for multicasting, testing, and other specific uses), IPv6 uses up to 128 bits which provides 2128 addresses or approximately 3.4 * 1038 addresses. Well, maybe we should say it is extremely extremely extremely huge :)

IPv6 Address Types

Address Type Description
Unicast One to One (Global, Link local, Site local)
+ An address destined for a single interface.
Multicast One to Many
+ An address for a set of interfaces
+ Delivered to a group of interfaces identified by that address.
+ Replaces IPv4 “broadcast”
Anycast One to Nearest (Allocated from Unicast)
+ Delivered to the closest interface as determined by the IGP

A single interface may be assigned multiple IPv6 addresses of any type (unicast, anycast, multicast)

Note: There is no broadcast address in IPv6

IPv6 address format


x:x:x:x:x:x:x:x – where x is a 16 bits hexadecimal field and x represents four hexadecimal digits.
An example of IPv6:

There are:
+ 8 groups of 4 hexadecimal digits.
+ Each group represents 16 bits (4 hexa digits * 4 bit)
+ Separator is “:”
+ Hex digits are not case sensitive, so “DBCA” is same as “dbca” or “DBca”…

IPv6 (128-bit) address contains two parts:
+ The first 64-bits is known as the prefix. The prefix includes the network and subnet address. Because addresses are allocated based on physical location, the prefix also includes global routing information. The 64-bit prefix is often referred to as the global routing prefix.
+ The last 64-bits is the interface ID. This is the unique address assigned to an interface.

Note: Addresses are assigned to interfaces (network connections), not to the host. Each interface can have more than one IPv6 address.

Rules for abbreviating IPv6 Addresses:

+ Leading zeros in a field are optional

2001:0DA8:E800:0000:0260:3EFF:FE47:0001 can be written as


+ Successive fields of 0 are represented as ::, but only once in an address:

2001:0DA8:E800:0000:0000:0000:0000:0001 -> 2001:DA8:E800::1

Other examples:
– FF02:0:0:0:0:0:0:1 => FF02::1
– 3FFE:0501:0008:0000:0260:97FF:FE40:EFAB = 3FFE:501:8:0:260:97FF:FE40:EFAB = 3FFE:501:8::260:97FF:FE40:EFAB
– 0:0:0:0:0:0:0:1 => ::1
– 0:0:0:0:0:0:0:0 => ::

IPv6 Addressing In Use

IPv6 uses the “/” notation to denote how many bits in the IPv6 address represent the subnet.

The full syntax of IPv6 is


+ ipv6-address is the 128-bit IPv6 address
+ /prefix-length is a decimal value representing how many of the left most contiguous bits of the address comprise the prefix.

Let’s analyze an example:
2001:C:7:ABCD::1/64 is really
+ The first 64-bits 2001:000C:0007:ABCD is the address prefix
+ The last 64-bits 0000:0000:0000:0001 is the interface ID
+ /64 is the prefix length (/64 is well-known and also the prefix length in most cases)

In the next part, we will understand more about each prefix of an IPv6 address.

Comments (50) Comments
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  1. Paulie
    July 5th, 2011

    @9tut Thank you so much for this Tutorial, This was the most difficult chapter for me now I know I’m gonna make it.

  2. Khumi
    July 6th, 2011

    Very Nice Tutorial …

  3. vinicius
    July 7th, 2011

    9tut, thanks so much. Its very helpful. :)

  4. cool
    July 16th, 2011

    This is very helpful tutorial for me.

  5. wilson
    July 18th, 2011

    i want to knw more about addressing and vlms

  6. Nabeel
    August 9th, 2011

    Thanks. This is very helpful to me for IPv6 key points.

  7. 9tut is Awesome
    August 24th, 2011

    Thank you and everybody else who contributes to this site, without these resources I would have failed my exams, even with the year and a half of schooling in cisco. Your contribution to my studies have been immeasurable, for that I Thank You!

  8. Paco
    September 6th, 2011

    Thanks a lot man, a well done and nice summary of what IPv6 is…

  9. Anonymous
    September 14th, 2011

    thanks very much , keep it up . it would be great evolution of explanation

  10. Irish Lecpuracn
    September 14th, 2011

    great task

  11. Joe
    September 22nd, 2011

    How do you subnett IPv6?

  12. Anonymous
    September 23rd, 2011

    @9tut….Thanks a lot.
    IPv6 is new to us.As a beginner, it is difficult to study.
    Ur explanation is easy to understand and make us clear.

  13. Mouhammad
    September 24th, 2011

    thank you 9tut.com

  14. Tweety
    September 28th, 2011

    Thank you 9tut.com Am very grateful. Am sure this will help me pass the exam.

  15. Liping
    October 13th, 2011

    Great summary, thanks 9tut.com

  16. Biggest 9TUT Fan!!!!
    October 20th, 2011

    Excellent!!!!Helped me to clarity.Cheers!!!

  17. sunil
    October 21st, 2011

    we don’t want to go for subnetting in ipv6…….ter r 3.4*10^32 ip add r available in ipv6 ………

  18. Pete
    October 27th, 2011

    + Hex digits are not case sensitive, so “DBCA” is same as “dbca” or “DBca”…

    From ipv6 WIKI:
    The hexadecimal digits are case-insensitive

    Can you verify which once is accurate ?

  19. xallax
    October 27th, 2011

    not case sensitive = case-insensitive. true

  20. umesh
    November 3rd, 2011

    problem solved

  21. Matteo “roghan” Cappelli
    November 23rd, 2011

    Hi, in the Special IPv6 Addresses table lack this value:

    Site-local address – FEC0::/10

    In this way the table is full and correct…

  22. abdou
    November 23rd, 2011

    @ 9tut
    thnks to you first for this explanations

    explain for me please
    global unicast address
    how it starts (2 and 3) what about the /3 prefix also meant.

    + starts with a 2000::/3 prefix (this means any address beginning with 2 or 3).

  23. Eng-Support
    November 26th, 2011


    2000 >>> it is a hexadecimal number means 4 bits binary for every number
    2 >>> 0010

    /3 >>> means first 3 bits of this (001) that can begin with 2 or 3

    hope this may be useful to u ;)

    @9tut plz ensure this answer & this tutorial was very useful thanks to u ;)

  24. z
    December 4th, 2011

    anyone plz explain
    what is “169.254.x.x” in IPv4…is it valid for host ?

  25. xallax
    December 4th, 2011

    windows xp and later will give a random IP on the network to hosts that could not get an IP from the DHCP server.
    it is the way windows made it so that hosts can still communicate with devices on the network even tho the host did not get a valid configuration from the DHCP server.

  26. CiscoMan
    December 21st, 2011

    @9tut : I think you should add fc00::/7 = Unique Local Addresses which can be used like RFC1918 IPv4 private addresses.

  27. moshe
    December 24th, 2011

    Who ever you are… U are Great.. Please dont get tired… you help, encourage people like me..
    Happy Holiday.

  28. hmeister
    January 18th, 2012

    169 addressing is known as APIPA…
    Definition: A feature of Microsoft Windows, APIPA is a DHCP failover mechanism for local networks. With APIPA, DHCP clients can obtain IP addresses when DHCP servers are non-functional. APIPA exists in all modern versions of Windows except Windows NT.

    Just Google APIPA and you will find plenty of information on this.

  29. hmeister
    January 18th, 2012

    Here is a VCE for IPv6 questions…

  30. serial
    January 18th, 2012

    thanks hmeister! :)

  31. srini
    February 10th, 2012

    thk hmeister.keep going

  32. H K SINGH
    February 11th, 2012

    very simple and excellent explanation of IPv6 , never forgettable , thanks

  33. john
    February 14th, 2012

    very helpful……….thanks!!!!!!!!!!

  34. rakesh shah
    February 16th, 2012


  35. sura
    February 18th, 2012


  36. Arpit
    February 25th, 2012

    @9tut: @Xallax: Please validate that Every IPV6 has at least one loopback address. In tutotrial I am not find anything regarding this.

    Is it true?? Please explain the same

  37. xallax
    February 25th, 2012

    ::1/128 is the loopback address by default.

    check the second page of this tutorial plz

  38. Gad
    February 27th, 2012

    great site
    A small mistake though, if I’m not mistaken myself … you wrote :
    “The size of address range assigned to the RIR may vary but with a minimum prefix of /12 and belong to the following range: 2000::/12 to 200F:FFFF:FFFF:FFFF::/64.”
    I believe the range is up to 2FFF:FFFF:FFFF:FFFF:FFFF/64 and not 200F


  39. Lyes
    March 7th, 2012

    Thank you it’s the first time that i read a very helpful tutoriel about ipv6

  40. dipesh shah
    April 7th, 2012

    gr8 information… THANK YOU !!!

  41. theorifice
    April 9th, 2012

    “Thank you it’s the first time that i read a very helpful tutoriel about ipv6”
    > Agreed.

  42. Zach
    May 10th, 2012

    I passed yesterday. I had a question where I had to identify FF02::9 as a RIP multicast from a list of 4…

    another that was clearly not the answer

  43. Akiii
    May 13th, 2012

    Great Explanation…
    Good For you 9tut.com

  44. mbeu
    May 22nd, 2012

    Excellent tutorial!

  45. boydreamer
    June 13th, 2012

    …this site very helpful to everyone, including me preparing for the exam! its my first time to
    read IPV6 and its amazing you simplify it for everyone to understand it. Hope you continue
    to share your knowledge and also others who visited this site..GBU

  46. Nuwan Silva
    June 13th, 2012

    Thanks you.It is a very nice tutorial.

  47. agg46357
    June 14th, 2012

    may I ask how to configure IPV6 isnt it the same with IPV4 configuration..?

  48. kuljit
    June 15th, 2012

    this detail is not enough its jst only base in two or three lines please give more detail on site fr student help

  49. Miguex
    June 17th, 2012

    Thanks 9tut

  50. Devine
    June 24th, 2012

    Very nice explanation…easy for be gainer

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