Version 6 of the Internet protocol (IPv6) is a key enabler of the Internet of Everything (IoE). People, data, and things all need IP addresses to connect to the Internet. But we’ve already run out of IP addresses under IPv4, which dictates almost all (98.5 percent) of Internet traffic today. Even with all of the attention IPv6 has received, confusion and misinformation abound.

I’m extremely pleased to have Mark Townsley, Cisco Fellow and recognized industry expert on IP, explore IPv6 over a series of three blogs.

In these posts, Mark will demystify IPv6, discuss how to best make the transition from IPv4 to IPv6, and take a look “under the hood” of IP so that companies and industries can get the most value from IoE.


I’d like to thank  Dave for this opportunity to write about IPv6. As the Internet of Things (IoT) grows into IoE as people and data join the billions of   devices and machines already connected to the Internet, a smooth and rapid transition from IPv4 to IPv6 becomes even more critical.  And while much work has been done on this front, there is still much to do. In this first blog about IP, I’d like to address the five questions I regularly receive on my blogs, at industry events, and from business executives.

 1.  What is the Internet Protocol (IP) and why is it important to the Internet?
IP is the “lifeblood” of the Internet. If you could “see” information in its raw form as it is exchanged between devices and passes over radio waves, copper wires, and fiber optic cables, you would notice tiny, similar-looking, packages of digital information called IP packets. These packages of 1s and 0s are the fundamental building blocks of the Internet and, in many ways, are analogous to the atoms that make up physical matter or the cells in living creatures.

At any given period of time, there are literally trillions of IP packets zooming across the network. Small bits of “header” information tell routers and switches where the information came from and where it is going so that it reaches its proper destination. This adoption of IP has been nothing short of a revolution in worldwide electronic communication.

2.  What is IPv6 and why should I be concerned about it?
IP was originally developed in an advanced research laboratory. There were several earlier versions that predated the use of IPv4, which became commercially popular in the 1980s and 1990s and which is broadly used today. IPv6, the latest IP version, was developed to address several challenges of its predecessor. Most important, IPv6 overcomes the fundamental limit of 4.3 billion globally unique addresses that has been present in IPv4 since its inception in 1981.

Because the Internet is so engrained in our lives, it is critical that we migrate from IPv4 to IPv6 without disruption, an equally challenging and important task. I sometimes compare this task to swapping out the wheels on a high-speed train without alarming the passengers.

Whether you are an IT professional, technology enthusiast, or business executive, I believe it is important for you to be well aware of the limitations of globally unique IPv4 addresses and the move to IPv6 which is currently underway.  These topics are important because they will greatly influence the future growth of the Internet for the billions of people who rely on it to live, learn, work, and play.

3. If we did run out of IPv4 addresses last year, why is the Internet still operating and growing?
Imagine an enormous playing field with 4 billion unique squares in a grid. Now, visualize large groups of squares being assigned to various organizations, businesses, and Internet service providers. Next, picture individual squares within these groups being populated by PCs, laptops, tablets, smartphones, servers, and other computing devices. Finally, imagine that you can rapidly and efficiently send a packet of information to the devices that reside in any square.

Because the number of squares is fixed at approximately 4 billion (as in IPv4), adding more and more devices to the playing field makes it evermore crowded. While all of the devices can fit for a while, the system inevitably stops growing and becomes less efficient. This is where we are with the Internet today—IPv4 is still working, but we need a new chessboard (IPv6), so to speak, if we want the Internet to continue growing and functioning as we expect it should.

4. Why is IPv6 important for IoE?
IPv6 brings us a much, much larger playing field on which to efficiently operate. In the case of IoE, IPv6 allows for a nearly limitless number of IP addresses, which will be required to connect the tens of billions of people, process, data, and things that will make up IoE.

Specifically, IPv6 quadruples the number of bits in the IPv4 address field from 32 to 128. This increases the number of networks that can be reached directly as well as allows for automatic configuration of IP addresses connected to a given local area network (LAN). All in all, this change gives us more capabilties as well as a theoretical playing field of 2^128 squares in which to put devices—enough, in fact, to put every atom on the surface of earth into its own square more than one hundred times over.

5. What happened to IPv5?
The first four bits of every IP packet contains a number that indicates what type of IP packet follows. These bits are called, for better or worse, the IP “version” field. IPv4 packets have the number 4 in this field (0100), and IPv6 packets use the number 6 (0110).  IPv5 (0101), dates back to a project started as early as 1979 in what eventually became the Internet Stream Protocol. Despite having the number 5 to distinguish it from other types of IP traffic, IPv5 was never considered as a successor to IPv4. IPv6 really is the next iteration of IP.

My next blog will describe the state of IPv6 deployment on the Internet today, and provide insights into how business and technology leaders can make the transition from IPv4 to IPv6 as seamlessly as possible. Please let me know what questions you have about this important transition so I can address them in my next post.

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