This month IPv6 hit its 21st anniversary, but outside of Google, cloud providers, cell phone companies and ISPs, who really cares? One would think by now it would be widely adopted or dead, as technologies rarely last two decades if they’re unsuccessful. Estimates are that between 5% and 25% of Internet traffic is IPv6, and adoption rates vary greatly between countries. So what about the other 75% to 95% of Internet traffic? It’s using IPv4, you know those addresses of the form 192.168.1.1, technology which is 35 years old! These addresses resolve into four bytes that provide 4.3 billion unique numbers that can be assigned to publicly routed devices.

Back in 1983 having a worldwide network with a potential capacity of 4.3 billion connected devices was inconceivable. The IPv4 system was designed to link supercomputers together across the globe, military installations, large company mainframes and perhaps minicomputers used by smaller companies. For those who didn’t live through 1983, Radio Shack ruled the personal computer market with the TRS80 Model I, III, and the Color Computer. If you were online you paid CompuServe and dialled in via a 300 baud (bit/sec modem). Personal computers from Apple and IBM were just hitting the market, and cell phones were nothing more than glorified two-way radios addressable via a phone number, while selfies were called Polaroids, and you waited a minute or so to see a low quality “instant” picture. Who could have imagined then that soon a significant percentage of the people on the planet would have networked computers in their pockets, strapped to our wrists, controlling our automobiles, refrigerators and septic systems?

Now for those who might not be keeping up, we “officially” ran out of publicly available IPv4 address blocks back in January 2011, yeah right, who knew? Now to be fair the January 31, 2011 date is when we exhausted the top-level blocks which are doled out to the five regional Internet registries (RIRs). Going one level farther down, the last of the RIRs to consume its final block was North America in September 2015. So how have we survived the end of available IPv4 addresses? Simple, since 1994 we’ve been playing a series of tricks to expand the available address space beyond 4.3 billion. Suppose like me you have a single IPv4 Internet address on your home router, inside your home network the router and all the devices use an address on that network of 192.168.1.X. Your router then uses a trick called Network Address Translation (NAT) to map all the 192.168.1.X devices on your network to that single IPv4 address. Brantley Coile founded a company in 1994 called Network Translation that patented NAT, then rolled it out in a device that Cisco later bought and rebranded the PIX Firewall (Private Internet eXchange). Today the vast majority of Internet-connected devices are using a NAT’d address. These days it’s highly unlikely that a company will assign a publicly routed Internet address to a laptop or workstation. I joined IBM Research back in late 1983, and by 1987 was standing up servers with their own unique publicly routed 9.X.X.X addresses. This was before the days of firewalls and security appliances. At the time IBM was one of roughly 100 entities worldwide who had their own class A Internet address space (an IPv4 address starting with 126 or less, for example, General Electric has 3, IBM 9, HP 15, and Ford 19). If you control a class A address you have 16 million publicly routable Internet addresses at your disposal.

Administrators for decades have trained ourselves to grasp a four-byte number like 10.5.17.23, for example, so we could then key it into another device and manage or networks. We invested time in knowing IPv4 and building networks to meet our needs. IPv6 address look like 2001:0db8:85a3:0000:0000:8a2e:0370:7334, this is not human-friendly. That is why inside large companies, where the administrators are familiar with IPv4, there’s resistance to moving to IPv6 addresses. IPv6 is designed for automated machine management. Personally, this spring I was assigned the first IPv6 address I took note of when we converted over to Google Fiber at home. So what was the first thing I did once the fibre was active? I requested an IPv4 address. It turns out there are several servers in my house which I need to reach remotely, and I wasn’t about to begin pasting in an IPv6 address whenever I needed to connect with them. There may be a better way, but I fall back on what I know and trust, it’s human nature. 

Today most of our new Internet edge devices, for example, routers and smartphones, are intelligent enough that they self-configure and the whole issue of IPv4 to IPv6 conversion will slowly fade into the background. Within the home or the Enterprise though, where devices need a human touch, IPv4 will live long and prosper.