How does someone obtain a large block of IPv6 adresses?

Question

I've been inspired by the "IPv6 enabled Christmas tree" featured on Hackaday.io a few weeks back featuring an led display that uses 300 billion IPv6 addresses to allow users to control it.

My question is this:

How could I, as a user and not a big company, obtain a block of (maybe about 1000) IPv6 addresses to use? Is this something I would have to get from my ISP or could I get them a different way (if I can do it at all)?

Answer 1

That's a tiny block.

IPv6 addresses aren't counted individually, except by cheapskate VPS hosting companies. More often, a /64 subnet containing 2^(128-64) addresses – 18 billion billion addresses – is used as a single unit of distribution. If your ISP claims to support IPv6, expect that you'll get at least one /64.

Many ISPs freely provide their customers with a larger prefix, e.g. /60 or /56; this isn't said to have 2^(128-56) addresses, but rather "16 subnets" or "256 subnets". Each subnet has a practically infinite number of addresses – it's the number of subnets that is limited.

In both cases, residential ISPs typically use DHCPv6-PD to allocate prefixes on demand, so that's something your router needs to do automatically. Some ISPs might instead do static assignments via support tickets.

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(Routing tables can work with any prefix, from /0 to /128, but certain auto-configuration protocols expect /64 for the on-link subnet. You can use e.g. /96's or /112's but it'll be troublesome and not worth the time. Hence the usage of /64 as a standard unit.

That said, of course, if you're doing a special-purpose scheme like the christmas-tree thing, you're completely free to ignore subnetting and use all available bits as you wish.)

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As you can see, even a single standard subnet has a decent amount of addresses to work with. A /64 means it uses 64 bits for the 'network' part, so you have 128-64=64 bits available for yourself: that's already enough to encode RGB color, position, and intensity. Having a /56 would give you 128-56=72 bits, and so on. (For comparison, your original request of 1000 addresses is approximately a /118 with only 10 host bits.)

But if you want more than that, a /48 is normal starting prefix size for business customers (up to /44, or at least so the recommendation goes). Additionally, both of the largest surviving "IPv6 tunnel broker" companies – NetAssist and Hurricane Electric – provide a free /48 to anyone who signs up on their website. In both cases, this means 65536 subnets or 80 freely usable bits.

Finally, let's say you're an ISP, then becoming a direct member of a RIR (regional Internet registry) will give you a /32 up to /29 allocation just to begin with. A /32 contains 4294967296 subnets – as many as there are IPv4 addresses including even the reserved ones – and each subnet still has the same "practically infinite" amount of addresses.

That's a large block.