The transition from Internet Protocol v4 to IPv6 is well under way. But what happened to the IPv5, if it had ever existed? A corner of the veil is lifted.
An Internet Protocol is a communication protocol that establishes the way in which machines interchange data via the Internet, or any other IP network, at the level of their unique address. IPv4 was devised in the 1970s, and became operational in 1981. It then grew to become the foundation of the Internet and many corporate networks throughout the world.
The most important function of IPv4 is the identification of machines (hosts) based on their logical address, so as to transport data between them over a network. We call the logical address of a host in a network an IP address. IPv4 has its own address scheme, just like its successor, IPv6, would later have.
In IPv4 that scheme consists of four groups of bits, whereby each group contains a number from 0 to 225, separated by a dot: ###.###.###.### . As a user, you are not going to enter that figure in your browser, but the domain name. That domain name is translated into the IP address of the server by DNS (Domain Name System).
... to IPv6
Just do the maths: 4 groups of 8 bits at IPv4 come to 32 bits. That makes 2^32 or 4.3 billion Internet addresses possible. This figure may look high, but turns out not to be sufficient. The Internet has developed very fast worldwide. The number of computers with Internet access continues to rise. Moreover, the smartphone has become wildly popular. Now add the real explosion of everyday objects that can be connected to the Internet (Internet of Things; IoT), and it becomes clear that 4.3 billion addresses will simply not suffice.
Long before there was any talk of IoT, it was known that IPv4 would never be able to provide enough addresses. That is why since the 1990s, work has been under way on a new protocol, IPv6. IPv6 addresses contain 128 bits and consist of eight series with 4-digit hexadecimal numbers. These characters are letters from A to F and numbers from 0 to 9. A typical IPv6 address looks something like this: 2001:0db8:85a3:0000:0000:8a2e:0370:7334.
This opens up endless possibilities – trillions of IP addresses (for the whizz kids: 2^128). So we can sleep soundly in the future. In December 1998, IPv6 became a Draft Standard, and the rollout of the new IP could begin!
This rollout had a very slow start. At the end of the last century there was still no IP shortage at all. Software and hardware suppliers were not ready to rush to implement that new standard in their products. The change came later, certainly when the first problems with the availability of IPv4 addresses began to surface in Asia.
The adoption of the IPv6 is now well under way. Internet Society figures show that 17% of the Alexa Top Million Websites in 2018 work with IPv6, compared with 13% in 2017. Of the Top 1,000 Websites, 28% work with IPv6 in 2018, compared with 23% in 2017. The share of surfers who use Google services such as its search engine via IPv6 amounted to 26% in November 2018, and is growing by ca. 4.7% a year. Belgium deserves a special mention by the way: We are the first country in the world to deliver more than 50% of the traffic to large content providers via IPv6.
And what about IPv5?
“Alright, but what happened to IPv5?” you are bound to ask. Because that is really the reason why you are reading this article, isn’t it? Well, work was done on the fifth version of the Internet Protocol, but it never became an official version.
Experts realised already back in the 1970s that the Internet would not be able to handle all traffic in the future. At Apple, NeXT and Sun Microsystems created the Internet Stream protocol (ST), to stream voice and video over the Internet -- an effective protocol for transporting data packages at certain frequencies, while maintaining the communication. It would ultimately also serve as the basis for the development of technologies such as voice-over-IP (VoIP).
There was a problem, however: ST relied on the 32-bit way of addressing in the IPv4 protocol. So it led to the same ailment as IPv4: all the addresses would have been used by 2011. It was therefore decided to switch directly over to IPv6, which was already under development at the time.
And lo and behold: the tragic story of a protocol that was disposed of, even before it could become a standard…