Articles / 24/05/2019

IP Address Evolution: IPv4 vs. IPv6. Has IPv5 Gone Missing?

IPv4 and IPv6. IP address evolution

IP versions

IPv4 and IPv6 are the IP (Internet Protocol) versions that we currently use. Internet protocol allows our devices to connect to the Internet.

IP versions from 0 to 3 were experimental versions, used between 1977 and 1979. The following Internet Experiment Note (IEN) documents describe versions of the Internet Protocol before the modern version of IPv4:

  • IEN 2 (Comments on Internet Protocol and TCP), dated August 1977, describes the need to separate the TCP and Internet Protocol functionalities (which were previously combined.) It proposes the first version of the IP header, using 0 for the version field and known as IPv0.
  • IEN 26 (A Proposed New Internet Header Format), dated February 1978, describes a version of the IP header that uses a 1-bit version field, thus becoming IPv1.
  • IEN 28 (Draft Internetwork Protocol Description Version 2), dated February 1978, describes IPv2.
  • IPv3 was being developed somewhere between IPv2 and IPv4 versions but was not released.
  • IEN 41 (Internetwork Protocol Specification Version 4), dated June 1978, describes the first protocol to be called IPv4. The IP header is different from the current IPv4 header.

What do we use now, and why are we short of resources?

Our present – the IPv4

IPv4 stands for Internet Protocol version 4. It is the underlying technology that makes it possible for us to connect our devices to the web. Whenever a device accesses the Internet (whether it’s a PC, Mac, smartphone or another device), it is assigned a unique, numerical IP address such as

To send data from one computer to another via the Internet, data packets must travel across the network containing the IP addresses of both devices.

Without IP addresses, computers would not be able to communicate and send data to each other. It is essential to the web infrastructure, thus in 1983, IPv4 was developed and deployed to use worldwide till today.

Why are we running out of IPv4 addresses?

IPv4 uses 32-bits for its Internet addresses. That means it can support 2^32 IP addresses in total — around 4.29 billion. That may seem like a lot, but all 4.29 billion IP addresses have now been assigned to various institutions, leading to the IPv4 depletion crisis we face today.

Let’s be clear, though – we haven’t run out of addresses quite yet. Many of them are unused and in the hands of institutions like MIT and companies like Ford and IBM. Heficed IP Address Market offers the solution to monetize unused IP spaces.

More IPv4 addresses are available to be assigned, and more will be traded or sold (since IPv4 addresses are now a scarce resource), but they will become a more limited commodity over the next two years until it creates a problem for the web.

What is Internet Protocol version 6 (IPv6)?

IPv6 is short for “Internet Protocol Version 6”. IPv6 is the Internet’s next-generation protocol, designed to replace the current Internet Protocol, IP Version 4.

IPv6 is a standard developed by the Internet Engineering Task Force (IETF), an organization that develops Internet technologies. The IETF, anticipating the need for more IP addresses, created IPv6 to accommodate the growing number of users and devices accessing the Internet. As mentioned before, IPv4 uses 32-bit addresses, which allows 4.29 billion unique addresses.

In comparison, IPv6 addresses are 128 bits, which allow for approximately three hundred and forty trillion unique IP addresses.

An example of IPv6 address is:


This time, it is for real

Major Internet service providers (ISPs), home networking equipment manufacturers, and web companies around the world united to redefine the global Internet and permanently enable IPv6 for their products and services on 6th June 2012.

Some of the participants that you, for sure know are:

AT&T, D-Link, Google, Comcast, Free Telecom, Cisco, Yahoo!, Limelight Networks, Internode, Microsoft Bing, Facebook, Akamai Technologies, KDDI, and others…

Since then, participation in the World IPv6 Launch and usage of IPv6 around the world has continued to grow and is immensely increasing.

Benefits of IPv6 vs. IPv4

IPv6 offers a large number of IP addresses compared to IPv4, but what are other benefits of IPv6?

One interesting feature of IPv6 is that addresses can be assigned automatically and dynamically by the client device, meaning that there is no need for a DHCP server. It means that you can plug a laptop to your local network, and it will get an address prefix from any router it finds and then generate an IP for itself for that network, based on the hardware MAC address.

In practice, this means simpler routers and less overhead for managing IP attribution. It will also mean even fewer configuration requirements.

Of course, you can still assign addresses to devices via DHCPv6, but it is up to you.

Multiple network addresses allocated to the same device is another interesting feature that IPv6 brings to us. You get the ability to assign two or more addresses to the same device. You can thus stay connected to several networks at the same time, which is a great boon for flexibility.

Apps will be able to choose the network they need or have access to, and you won’t have to choose between networks anymore.

IPv4… IPv6… Has IPv5 gone missing?

In the late ’70s, IPv5 was named ST, the Internet Stream Protocol. IPv5, or ST as it was known, was used by the likes of Apple, NeXT, and Sun to guarantee service across a network. ST was good at maintaining communication while transferring specific data packets on select frequencies.

IPv5 was merely created for experimental reasons, specifically for video and voice transmissions.

There is an old joke that is traveling from person to person in the vast waters of the Internet:

“Did you know? IPv5 is available only for Windows 9…”

IPv4 and IPv6 coexistence

Right now, IPv4 and IPv6 both coexist together. The way forward, though, is seen the transition to IPv6, which has already started and is considered as the next stage of IP evolution.