IPv6 Foundation Part 1: What is IPv6

IPv6 Foundation Part 1 - What is IPv6
What is IPv6? Why do we need IPv6? When will IPv6 be here? How do I get my IPv6 address­es? Find answers to these ques­tions and more right here!

Table of Con­tents

About this course

So you are inter­est­ed in IPv6, which is absolute­ly great!

IPv6 is not only the future of net­work­ing, it is already here today! All the big play­ers on the Inter­net are already IPv6 enabled and it is now time for you to join the par­ty!

This course cov­ers all major aspects of the new Inter­net Pro­to­col and what changed, com­pared to IPv4. You will under­stand the fun­da­men­tals and be ahead of your peers that are still on the sink­ing ship of IPv4! As of today, there are no IPv4 address­es left and we have no oth­er option but to go ahead and deploy IPv6.

IPv6 Act Now

IPv6 Foun­da­tion Part 1 — Intro­duc­tion: What is IPv6

What is IPv6?

IPv6 is the cur­rent ver­sion of the Inter­net Pro­to­col
 (IP). IP is used for com­mu­ni­ca­tion between machines in near­ly all net­works (LANs) and the Inter­net
 today. Its pre­de­ces­sor was IPv4 but we will not be turn­ing off IPv4 just now, as both tech­nolo­gies will be run­ning side-by-side on the Inter­net for years to come. With a mar­ket share of more than 30% of glob­al Inter­net traf­fic as of Jan­u­ary 2020, it means if you have not enabled IPv6 for your net­work or ser­vices, you are run­ning late and should do so right now.

Why do we need IPv6?

IPv4 was cre­at­ed in the ear­ly 1970s
. At the time, the high num­ber of devices on the Inter­net was not fore­seen
 by the Engi­neers who invent­ed the Inter­net

IPv4 address­es have 32 bits, so there are the­o­ret­i­cal­ly 4.294.967.296 avail­able address­es
. In real­i­ty, much less are actu­al­ly usable (no class D & E).

IPv4 address­es are exhaust­ed as of today, all avail­able address­es have been assigned, but the need for addi­tion­al address­es con­tin­u­al­ly increas­es

In the ear­ly days of the Inter­net, big blocks of pub­lic IPv4 address­es were allo­cat­ed to large cor­po­ra­tions, like whole /8s to a sin­gle com­pa­ny, because there was no class­less IP address­ing and no pri­vate IP address ranges yet. I will describe what this means in the fol­low­ing para­graphs.

Less than 221 /8s are avail­able in total
 for IPv4 (class A‑C, not count­ing 0/8, 10/8, 127/8).

About Class­ful IP Address­ing

Class­ful IP address­ing was used from 1981 until 1993
. Address­es were sep­a­rat­ed into 5 class­es (A, B, C, D, E)
. The net­work mask was fixed per class and could not be changed.

The class­ful net­works were:

Class Size of Net­work Num­ber in Bit Field Size of Rest Bit Field Num­ber of Net­works Num­ber of Address­es per Net­work Start Address End Address

Class A


Class B


Class C


Class D


not defined
not defined
not defined
not defined

Class E 


not defined
not defined
not defined
not defined

Class­less IP Address­ing

Class­less IP address­ing was intro­duced in 1993
 (RFC1518 and RFC1519)

Fixed class­es were aban­doned. A new class­less address nota­tion con­tains a “pre­fix” and a “host iden­ti­fi­er”
. The new tech­nol­o­gy was called Class­less Inter-Domain Rout­ing, in short: CIDR.

A typ­i­cal CIDR nota­tion is for exam­ple: —
 the pre­fix length is sup­plied after the slash.

The IPv4 class­less net­works are:

Classless Inter-Domain Routing CIDR Chart

Since the ear­ly 1990s it was clear, that IP address­es will not be enough

Two steps were tak­en to resolve the issue:

1993: change from “class­ful” to “class­less” (CIDR) address­ing (RFC1518, RFC1519)

1995: first IPv6 Draft RFC1883

1996: allo­ca­tion of pri­vate IP ranges that can over­lap in mul­ti­ple net­works: (,, accord­ing to RFC1918, “Address Allo­ca­tion for Pri­vate Inter­nets”)
. Until then, no pri­vate ranges were avail­able, so every host on a net­work, pri­vate and pub­lic, had to be assigned an offi­cial, pub­lic IP address. What a waste!

Still, the Inter­net grew so much more that these steps were not enough.

So final­ly, the next gen­er­a­tion of the Inter­net Pro­to­col had to be definied:

1998: IPv6 (RFC2460)

2017: IPv6 (Newest) RFC8200

When will IPv6 be here?

IPv6 is not com­ing, it is already here!
 The pro­to­col is near­ly 20 years old
 and was definied back in 1998 in RFC2460, “Inter­net Pro­to­col, Ver­sion 6 (IPv6)”
 and has been reg­u­lar­ly updat­ed ever since up to the cur­rent­ly newest def­i­n­i­tion of RFC8200 from 2017.

In the fol­low­ing years since 1998 the IPv6 Inter­net grew only slow­ly, but steadi­ly.

Most providers and com­pa­nies were still a bit afraid, that enabling IPv6 for their ser­vices would break cus­tomer-fac­ing appli­ca­tions and ser­vices, so they were most­ly wait­ing for every­body else to enable IPv6 first and fix the issues that might arise from it.

Final­ly, Indus­try giants Face­book, Google, Yahoo, Aka­mai Tech­nolo­gies, and Lime­light Net­works decid­ed to have a World IPv6 Day on 2011/06/08 and enable the new pro­to­col from 00:00 on this day until 23:59 to see the effects and final­ly gath­er real world data. The event was a major suc­cess, so a new date was set:

World IPv6 Launch Day on 2012/06/06

The goal of this day was to final­ly enable IPv6 and keep it run­ning for good.

Since then, more and more net­works includ­ing all major Inter­net brands and key play­ers are IPv6-enabled.

IPv6 enabled networks

How do I get my IPv6 address­es?

Address­es on the Inter­net are assigned top to bot­tom with the fol­low­ing author­i­ty:

IPv6 RIR Network Authority

The total amount of IP address­es is divid­ed in dif­fer­ent pools for the dif­fer­ent regions of Region­al Inter­net Reg­istries (RIRs) and then can be request­ed and assigned to Local Inter­net Reg­istries (LIRs) — the providers.

How to get IPv6 address­es is a sub­ject that is out of scope for this IPv6 couse. I have cov­ered it in my Ger­man Post Wie erhält man IPv6 Adressen. An eng­lish ver­sion of the post will be made pub­licly avail­able in the near future.

Here is an overview of the Region­al Inter­net Reg­istry (RIR) author­i­ty for all IP address assign­ments:

Global RIR Authority

Today in 2020, we have sur­passed 30% of glob­al IPv6 adop­tion, which means that more than 30% of the clients on the Inter­net are not only IPv6 enabled but use IPv6 to surf the Inter­net.

Here are some very inter­est­ing sta­tis­tics on IPv6 adop­tion accord­ing to Google:

Global IPv6 Adoption according to Google

As you have learned before, IPv4 address­es are exhaust­ed, so IPv6 adop­tion will rise much more, since the amount of devices con­nect­ed to the Inter­net will increase with tech­nolo­gies like 5G, Inter­net of Things (IoT), Con­nect­ed Car and many more.

Sta­tis­tics on IPv4 deple­tion accord­ing to Pota­roo in /8s:

Global IPv4 Depletion according to Potaroo

Thank You

Thank you for attend­ing my Orig­i­nal IPv6 Mas­ter Class! You can book­mark this site to use it as a quick ref­er­ence in case you need to re-read some­thing and you can share this page to social media and your friends and col­leagues. Stay tuned to this blog for more in-depth sto­ries like this one.

Thank you so much for read­ing and fol­low­ing along!

Rec­om­mend­ed Resources for addi­tion­al read­ing

Apart from the links through­out this course I rec­om­mend the fol­low­ing resources for addi­tion­al infor­ma­tion:

  1. The Inter­net Soci­ety (ISOC) IPv6 Por­tal
  2. Test your IPv6 con­nec­tiv­i­ty on test-ipv6.com
  3. The offi­cial IANA list of assigned IPv6 address space is very inter­est­ing
  4. The Google IPv6 deploy­ment sta­tis­tics
  5. The RIPE NCC IPv6 work­ing group and mail­ing list

Book rec­om­men­da­tions on IPv6

I can rec­om­mend the fol­low­ing 3 books (Ama­zon refer­ral links) which I enjoyed read­ing:

This con­cludes IPv6 Foun­da­tions Part 1 — Intro­duc­tion: What is IPv6 of the Orig­i­nal IPv6 Foun­da­tion Mas­ter Class.

Back to IPv6 Foun­da­tion Course Index

Next Part: IPv6 Foun­da­tions Part 2 — IPv6 Address­ing & Sub­net­ting

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