You connected to this website from IP address If this address contains four fields separated by “.” characters (e.g., sorry, you are still on the Second Internet (you are using IPv4). If it contains up to eight fields separated by “:” characters (e.g. 2001:470:ed3d:1000::2:1), CONGRATULATIONS, you are already on the Third Internet! You have IPv6!

NOTICE: The content from the website https://v6edu.com has been merged into this website. The v6edu.com website will be decommissioned. The original content of ThirdInternet.com was for IPv6 advocacy, deployment issues, and discussion on impact of IPv6 on the Internet and society. The content from v6edu.com is pure technical training, for engineers. It contains the complete IPv6 Forum CNE6 (Certified Network Engineer for IPv6) course material. I will continue thirdinternet.com. The IPv6 Forum estimates that some 20M network engineers need to learn IPv6. This site is my attempt to address this need.

NOTICE: I have gone live with another website on cryptography and PKI, at https://pkiedu.com. It is also free.

This website contains information on a very exciting development happening right now on the Global Internet. We are partway through a generational change, kind of like going from 3G telephony to 4G, but much more important and much further reaching. This change will touch everyone using the Internet and fundamentally change the way most things on the Internet (and all telephones) work.

Years ago I read a great book on the creation of the Internet, called Where Wizards Stay Up Late. If you haven’t read this, go read it now. I was inspired by what these brilliant people had done and how they did it – one of the towering achievements of mankind. But I was sad that I was too late to help create the Internet (I was too late to help with putting the first man on the moon too – I graduated from High School about the time that Neil Armstrong stepped out onto Mare Tranquilitatis). When I discovered IPv6, I realized I may have been too late to help build the Internet I was using, but a whole new one was being built now. I began researching and mastering the technology, and am now helping to build this amazing new Internet. It will literally make the Internet you are using today (the Second Internet) look as much like a simple toy, as the Second Internet made ARPANET (the First Internet) look like a simple toy. I am fortunate to work with many of the key people involved in this globally, like Latif Ladid (head of the worldwide IPv6 Forum). I am currently the chair of the Singapore chapter of this organization.

The Internet is based on a foundation protocol known (cleverly enough) as the Internet Protocol (IP). We have been using one version of this protocol (IPv4) since 1983, and we are in the process of deploying the next generation of this protocol (IPv6) as we speak. What happened to IPv1 to IPv3? Those were only ever used in the lab – IPv4 was the first one released to the public. What happened to IPv5? There never was an IPv5. The four bit field in every IP packet header that specify the IP version is 0100 in binary (4 in decimal) for IPv4. The pattern 0101 (5) in that position in the IP header was used for a streaming protocol that is no longer used, but once that bit pattern was allocated by IANA, it could no longer be used for other things.

The project to find a successor to IPv4 was called IPng (IP next generation) (like Star Trek The Next Generation, which was popular then). There were four versions of IPng proposed, and the bit patterns 0110 (6), 0111 (7), 1000 (8) and 1001 (9) were used for the four proposed protocols. The candidate protocol with 0110 (6) in that field was the winning protocol, so IPv6 became the official successor to IPv4. Make it so, Mr. Crusher. The next version of IP will be IPv10. But don’t worry, that is probably 40 or 50 years away. Not my problem (I’m 66 as I write this).

The Internet is structured into four layers, not seven – that was the ISO Open System Interconnection model – see below, which is no longer deployed anywhere on Earth other than Computer Science professor’s brains and Cisco books. TCP/IP (and the four layer model) won the network wars in the real world long ago.

The bottom layer is the Link Layer (where Ethernet and Wi-Fi live). IPv4 and IPv6 live in the Internet Layer of the TCP/IP stack along with the Internet Control Message Protocol (ICMPv4 and ICMPv6). The next layer up is the Transport Layer, where UDP and TCP live. The top layer is the Application Layer, where most of the protocols you know and love live (e.g. HTTP, FTP, SMTP, IMAP, LDAP, etc). So, a complete stack might be HTTP over TCP over IP over Ethernet. The other layers (Application, Transport and Link) are mostly unchanged in the Third Internet, but the Internet Layer in the Third Internet is radically different from the one in the Second Internet. Think going from Columbus’ Santa Maria to the Starship Enterprise in one giant leap. Applications created for IPv4 require only minor changes to work over IPv6 (e.g. DNS address resolution, amount of storage required for IP addresses, etc).

Changes to protocols in the Application Layer (like HTTP 1.0 to HTTP 1.1) affect a few things, but changes in the Internet Layer (like IPv4 to IPv6) have a MAJOR impact on how the entire Internet works. A new version of a college textbook may affect a few people. Changing the official language in the US from English to Mandarin would affect everyone. The last change on the Internet at this level was in 1983 when IPv4 was deployed. Before 1983 there were very few people using the Internet (actually at the time it was called ARPANET – I call it the First Internet). I call the remaining bits of the Internet based on IPv4 (which is now at End of Life) the Second Internet, the Legacy Internet or the InterNAT. I call the new Internet based on IPv6 the Third Internet.

If you hear someone refer to IPv6 being a “Layer 3 protocol”, or characterizing network switches as “Layer 2” or “Layer 3”, they are using OSI terminology.

There is a free network configuration app for Windows called SixConf, here.