What is IPv6, and how is it different from IPv4?
IPv6 is the newer version of the Internet Protocol. It replaces the four-number IPv4 format with a much longer address, so there are enough addresses for every device, now and for the foreseeable future.
Why IPv6 exists
IPv4 addresses are 32 bits long, which allows about 4.3 billion of them. That sounded like plenty in the 1980s, but phones, laptops, televisions and sensors used them up. IPv6 addresses are 128 bits long, which is a number with 39 digits. Running out is not a realistic worry.
How they look different
IPv4: 203.0.113.25. IPv6: 2001:db8:85a3::8a2e:370:7334. IPv6 uses hexadecimal digits in groups of four, separated by colons. A run of zero groups can be shortened to a double colon, once per address.
What changes in practice
Most things work the same for you. A few differences are worth knowing:
- A device can have several IPv6 addresses at once, and some change regularly for privacy.
- IPv6 does not need the address sharing that IPv4 relies on, so devices can have their own public addresses.
- Websites and networks can support IPv4, IPv6 or both. Many home connections use both side by side.
Are you using it already?
Many providers across the UK and Europe now give customers IPv6. Open the My IP page: if the address contains colons, your connection used IPv6 to reach this site. If it shows four numbers, you used IPv4, which can simply mean your provider or router has not switched IPv6 on.
Common questions
Is IPv6 faster than IPv4?
Not by itself. Speed depends on your connection and the route taken. IPv6 can sometimes be slightly quicker where it avoids address sharing, but you should not expect a big difference.
Do I need to do anything to use IPv6?
Usually not. If your provider and router support it, it is switched on automatically. Otherwise you may need to enable it in your router settings or ask your provider.
Will IPv4 stop working?
Not any time soon. The two are expected to run side by side for many years.