Every single device that connects to the internet needs some form of unique address that can be identified and located. IP addresses provide this functionality. So, what is IPv6? What is IPv6 used for? And what is the difference between IPv4 and Ipv6?

IP stands for Internet Protocol: the communications protocol that allows each machine to have a unique ID and pass packets of data between networks. IPv6 is the most recent version, introducing countless new IPv6 addresses on top of the limited IPv4 collection, and including features that make a big difference to how IP addresses are organised.

IP addresses: the story so far

Before IPv6 addresses, there was IPv4. IPv4 was the first standardised, widely implemented version of an IP address, with development stretching back to the 1970s. A typical IPv4 address might look something like ‘’. But as the internet became rapidly commercialised in the 90s, it became clear that this ageing technology had some serious limitations.

How many IPv4 addresses are there?

IPv4’s 32-bit addresses theoretically put the maximum number of IPs somewhere around four billion. That may sound like a lot, but it’s a worryingly low number when you consider that there are over seven billion people on the planet, let alone individual devices.

Inevitably, IPv4 addresses have been running out. The core functionality of IPv4 comes from a time when widespread personal computers and mobile devices were still the stuff of science fiction. It was never intended to provide the vast numbers of addresses required by a hyper-connected society.

What is IPv6?

Developed by the Internet Engineering Task Force (IETF), an open standards organisation, IPv6 was brought in to solve the potential address shortage. It wound up becoming a Draft Standard in December 1998, but only achieved full Internet Standard status in July 2017. While IPv6's primary aim is to increase the amount of available IP addresses with IPv6 compatible websites, it also provides some efficiency and performance boosts over IPv4 along the way.

What is the difference between IPv4 and IPv6

Technical benefits associated with IPv6 addresses include hierarchical address allocation. This helps avoid fragmentation of IPv6 addresses and makes more efficient use of the address space. Multicast addressing is also expanded, simplified and optimised, allowing network packets to be transmitted to multiple destinations simultaneously.

But a major difference between IPv4 and IPv6 is its packet header structure. You could think of the header like the addressed envelope that contains the letter (the packet). IPv6 addresses do away with the more complex header structure of IPv4, with rarely used fields moved to optional extensions. The result is a more efficient packet forwarding via routers and improved overall performance.

But what about all those existing IPv4 addresses? Do they still work with IPv6 websites?

IPv6 to IPv4 traffic was not originally designed to be possible. But the reality of the modern internet means a wide variety of technical solutions allow the two to work together perfectly. The real question is whether IPv6 addresses will ever be the only choice for IP addresses.

How many IPv6 addresses are there?

Recognising the need for a massive boost in available address space, the IETF are working hard to ensure IPv6 never experiences the same exhaustion problem as IPv4. IPv6 addresses are all 128-bit, in theory providing a maximum of around 340 trillion, trillion, trillion addresses. An example IPv6 address might look something like ‘2001:0db8:85a3:0000:0000:8a2e:0370:7334’.

Needless to say, we won’t be running out of IPv6 addresses any time soon.

How to enable and disable IPv6

If you're interested in how to change IPv4 to IPv6, the process is relatively simple. Fortunately, IPv6 is now a mandatory part of Windows Vista onwards. This means that unless you're working on a very old computer, you shouldn't have to go through the process of enabling it.

But if you're on a Mac, the process does require a few steps. First, go to system preferences and select your chosen network option. Then proceed to advanced options and find the TCP/IP tab and set the configure IPv6 option to automatic. Then repeat this process with your Wi-Fi or AirPort option.

To disable IPv6 on your Mac, simply change the IPv6 option from automatic to link-local only. To disable IPv6 on windows, go to your network and sharing centre, click on change adaptor settings, right click on the connection you want to disable IPv6 on and select properties. Find the IPv6 box and uncheck it –simple!

The future: will IPv6 replace IPv4?

With its comparatively minuscule address space, you might assume that IPv4 is dead and buried. But in reality, IPv4 is in great health, still accounting for about 75% of all internet traffic. The adoption of IPv6 websites is creeping up, but it certainly won’t be replacing IPv4 overnight.

However, you might have seen in the news that the European body that distributes IP addresses, RIPE NCC, has now officially run out of IPv4 addresses. It joins the North American body, ARIN, which ran out of addresses in 2015. The other three global distributors are not far behind. Due to this, more and more providers will now be forced to turn to IPv6 addresses. This should lead to higher adoption and compatibility rates.

Network address translation (NAT) technology is a saving grace for IPv4’s longevity. It allows organisations to run thousands of devices behind a handful of public-facing IPs. Similar techniques have also been employed by internet service providers, reducing the number of addresses required by their customers.

Long term though, it’s clear that IPv6 addresses will come to dominate, even if IPv4 sticks around for a long time. The coming decades will likely see an ever-increasing demand for colossal quantities of IPs. Especially now the internet of things (IoT) connects everything from fridges to thermostats – and every IoT device will need its own unique address. Universal IPv6 connectivity will be required to meet this demand, which means the number of IPv6 addresses will inevitably exceed those of IPv4.

At Fasthosts, we offer IPv6 addresses on all our servers. Whether you’re running a dedicated server, virtual private server, cloud server, or just a bare metal machine, it’s simple to assign multiple IPv6 addresses at no extra cost.

For even more articles on web hosting and internet tips and tricks, you can take a look at our blog on the Fasthosts website.