IPv4 is the old familiar Internet Protocol, You get addresses like 184.108.40.206, four numbers in the range 0 to 255. That means there are 2 to the power 32 possible IP addresses.
When this was designed, that sounded like a lot, enough for indefinite use. This is 4 billion addresses, which is enough for half the people on the planet. Plenty, yes? No. They didn't anticipate the huge popularity of the internet, and it turns out that these 4 billion addresses are not enough. And there is an IP address shortage.
This consists of eight numbers instead of four. Which is 16 billion billion addresses. And that should be enough for a long time.
Everyone uses IPv4 today. And people keep saying "We have to move to IPv6" because we've run out of IPv4 addresses.
And they've been saying that for seven years now.
So today, I decided to start making a move. Step one, talk to TalkTalk, to get some IPv6 addresses, and for them to route them to my connection. So I contacted TalkTalk.
They don't do IPv6. In April 2017, their Chief Operating Officer said that they will in future. But in the 14 months since then, there's been a deafening silence. And when I asked their tech people, they said they don't do IPv6 and didn't know when they might.
So I explained that when my contract comes up for renewal, the existence of IPv6 support will definitely be a factor in which service provider I choose.
I can't believe that they haven't done this yet.