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IPv6 Tutorial

June 24th, 2011 Go to comments

The Internet Corporation for Assigned Names and Numbers (ICANN) is responsible for the assignment of IPv6 addresses. ICANN assigns a range of IP addresses to Regional Internet Registry (RIR) organizations. 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.


Each ISP receives a /32 and provides a /48 for each site-> every ISP can provide 2(48-32) = 65,536 site addresses (note: each network organized by a single entity is often called a site).
Each site provides /64 for each LAN -> each site can provide 2(64-48) = 65,536 LAN addresses for use in their private networks.
So each LAN can provide 264 interface addresses for hosts.

-> Global routing information is identified within the first 64-bit prefix.
Note: The number that represents the range of addresses is called a prefix


Now let’s see an example of IPv6 prefix: 2001:0A3C:5437:ABCD::/64:


In this example, the RIR has been assigned a 12-bit prefix. The ISP has been assigned a 32-bit prefix and the site is assigned a 48-bit site ID. The next 16-bit is the subnet field and it can allow 216, or 65536 subnets. This number is redundant for largest corporations on the world!

The 64-bit left (which is not shown the above example) is the Interface ID or host part and it is much more bigger: 64 bits or 264 hosts per subnet! For example, from the prefix 2001:0A3C:5437:ABCD::/64 an administrator can assign an IPv6 address 2001:0A3C:5437:ABCD:218:34EF:AD34:98D to a host.

IPv6 Address Scopes

Address types have well-defined destination scopes:

IPv6 Address Scopes              
Link-local address + only used for communications within the local subnetwork (automatic address configuration, neighbor discovery, router discovery, and by many routing protocols). It is only valid on the current subnet.
+ routers do not forward packets with link-local addresses.
+ are allocated with the FE80::/64 prefix -> can be easily recognized by the prefix FE80. Some books indicate the range of link-local address is FE80::/10, meaning the first 10 bits are fixed and link-local address can begin with FE80, FE90,FEA0 and FEB0 but in fact the next 54 bits are all 0s so you will only see the prefix FE80 for link-local address.
+ same as 169.254.x.x in IPv4, it is assigned when a DHCP server is unavailable and no static addresses have been assigned
+ is usually created dynamically using a link-local prefix of FE80::/10 and a 64-bit interface identifier (based on 48-bit MAC address).
Global unicast address + unicast packets sent through the public Internet
+ globally unique throughout the Internet
+ starts with a 2000::/3 prefix (this means any address beginning with 2 or 3). But in the future global unicast address might not have this limitation
Site-local address + allows devices in the same organization, or site, to exchange data.
+ starts with the prefix FEC0::/10. They are analogous to IPv4’s private address classes.
+ Maybe you will be surprised because Site-local addresses are no longer supported (deprecated) by RFC 3879 so maybe you will not see it in the future.

All nodes must have at least one link-local address, although each interface can have multiple addresses.

However, using them would also mean that NAT would be required and addresses would again not be end-to-end.
Site-local addresses are no longer supported (deprecated) by RFC 3879.

Special IPv6 Addresses

Reserved Multicast Address Description
FF02::1 + All nodes on a link (link-local scope).
FF02::2 + All routers on a link
FF02::5 + OSPFv3 All SPF routers
FF02::6 + OSPFv3 All DR routers
FF02::9 + All routing information protocol (RIP) routers on a link
FF02::A + EIGRP routers
FF02::1:FFxx:xxxx + All solicited-node multicast addresses used for host auto-configuration and neighbor discovery (similar to ARP in IPv4)
+ The xx:xxxx is the far right 24 bits of the corresponding unicast or anycast address of the node
FF05::101 + All Network Time Protocol (NTP) servers

Reserved IPv6 Multicast Addresses

Reserved Multicast Address Description
FF02::1 + All nodes on a link (link-local scope).
FF02::2 + All routers on a link
FF02::9 + All routing information protocol (RIP) routers on a link
FF02::1:FFxx:xxxx + All solicited-node multicast addresses used for host auto-configuration and neighbor discovery (similar to ARP in IPv4)
+ The xx:xxxx is the far right 24 bits of the corresponding unicast or anycast address of the node
FF05::101 + All Network Time Protocol (NTP) servers

Comments (48) Comments
Comment pages
1 2 3 681
  1. uday
    March 8th, 2014

    Good summary of IPv6 !!

  2. Reza
    April 9th, 2014

    Thanks. Good tutorial on IPv6.

  3. Salam
    April 17th, 2014

    Very Nice, to understand about IPv4

  4. Osama Bin Laden
    May 3rd, 2014

    Thank you

  5. Abdulazeez
    May 6th, 2014

    nice one and cool.God bless you.

  6. fatema anwar
    May 7th, 2014

    really helpful …thanx

  7. Sadrul
    May 12th, 2014

    Thanks……..really helpful..!!!!!!

  8. AT
    May 14th, 2014

    great tutorial…easy to understand

  9. Boudcha
    May 22nd, 2014

    Than you it is veru usefull tuturial

  10. Saroj Dongol
    May 31st, 2014

    Thanks you so much . it clear my doubt about ipv6

  11. Anonymous
    June 9th, 2014

    Excelente, muy acertado el tutorial

  12. sepehr
    July 20th, 2014


  13. Anonymous
    July 23rd, 2014

    Hello everyone here,

    I was wondering if any one has the CCNA CBT Nuggets.
    Especially IPv6 part.
    Feel free to send them to my email address:arwa.alansary@yahoo.com

    Also, I am going to have my exam on August 14. If you have any useful resources, please let me know.


  14. hadii
    August 9th, 2014

    thank you for the explanation. am ok now.

  15. Kim Jong-un
    August 19th, 2014

    this website is gold! thanks alot

  16. Anonymous
    September 30th, 2014


  17. wondering
    October 21st, 2014

    Are any of these ipv6 questions on the test

  18. Abbas Ali
    October 27th, 2014

    I want to ask something that if a person gets prepared for CCNA and CCNP but have n’t give the Industry paper,Can he appear for CCIE?

  19. sanjeev yaliballi
    October 29th, 2014

    nice one…

  20. hafeez
    December 15th, 2014

    very good concept

  21. Terror IST
    January 12th, 2015

    Helped me a lot to kill more People
    your obama

  22. rocknolds
    February 20th, 2015

    does this mean that when we are assigning static IPv6 to our computer/host for example, we can cause IP address conflict to possibly another host that is located on another place or organization?

  23. afzal
    April 14th, 2015

    comprehensible examples!

  24. Anonymous
    June 18th, 2015

    i have a questions 314

  25. G.S.G
    June 23rd, 2015

    Thanks for this information. It’s help me a lot.

  26. Onésimo
    August 7th, 2015

    Very usefull summary

  27. ANGY
    September 24th, 2015


  28. Anonymous
    September 29th, 2015

    Very nice tutorial

  29. amoskbc
    October 14th, 2015

    ipv6;kindly help,,basic concepts

  30. Steptabs
    October 15th, 2015

    Nice one,very informative

  31. Anonymous me
    December 1st, 2015

    Thanks for this 9tut.. You rock! Much appreciated

  32. masoom siddiqui
    December 14th, 2015

    thanks team for inform me

  33. Anonymous
    February 29th, 2016

    nice and good content.

  34. Anonymous
    March 17th, 2016

    Can each interface have more than one IPv6 address?

    In this tutorial, it is mentioned that:

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

  35. Anonymous
    April 28th, 2016

    i want to learn the subneting with ipv6 address, please help me. thanks

  36. Cris
    May 18th, 2016

    Excellent tutorial on IPv6. Thank you…

  37. arsh
    May 26th, 2016

    very good. Could someone can send me icnd 100-101 dumps. arshadnazir at gmail dot com

  38. adex
    May 27th, 2016

    i dont undrstand ipv6 explanation

  39. adex
    May 27th, 2016

    pls any help bcos i score 44% on it at my ccna

  40. adex
    May 27th, 2016

    am ccna certified since 2015 but i dont know where i can apply it for work

  41. ASM
    August 31st, 2016

    if you need help in OSPF Ipv6 , please check out this Link http://asmed.com/cisco-ccna-ospf-ipv6-configuration/

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    September 8th, 2016

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    December 1st, 2016

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    December 5th, 2016

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    December 7th, 2016

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