[ahsteele]

It’s really hard to even comprehend how large IPv6 is. I have found that extreme examples tend to help people get there. Here are some I’ve used in the past.

There are enough IPv6 Addresses for 4.77 x 10^28 for every living person.

If each IPv6 address was a grain of sand…

That’s 2.39 × 10^18 of addresses per person, or roughly enough sand sized addresses to equal about 1.8 times the volume of earths ocean per person.

At sand scale all IPv6 addresses would take the volume of 12 sols.

Conversely, all the IPv4 addresses in this sand scale would slightly over fill an oil drum.

From “IPv6 Addresses: Big Numbers, Big Solutions”: https://www.osti.gov/servlets/purl/1365362

[Dylan16807]

I think it's more useful to comprehend it as 64+64 though.

We can give every person a million local networks, with unlimited devices on each local network. That's more accurate and also easy to think about.

[timewizard]

In current practice it's more like a global 61+64. We're all inside the globally routable /3 with ULAs on the side.

[gorgoiler]

Chess has 1e100 possible games but the more practical metric is that the average game involves 40 black moves and 40 white moves.

Similarly, it’s better to think of the depth of a network’s topology. The size of the tree when full is immaterial, especially when the last 64 bits is intended to be so sparse that random address assignment is viable.

[gorgoiler]

I missed the edit deadline and wanted to add:

So instead of talking about there being 2^128 addresses, it’s more useful to talk about there being 4k global regions (/12 RIRs), assigning /32s to ISPs in their region.

Each ISP can assign a /48 to each customer site, which can then subdivide into 256 buildings with 256 VLANs each (or some other balance of the these, eg 8 buildings with 64 floors each and 128 VLANs on each floor) with the hosts selecting randomly (or SLAACly) from the final 64 bits.

Some ISPs where customers are in a single dwelling will only give you a /56.

[nottorp]

> It’s really hard to even comprehend how large IPv6 is.

But the allocations for a single device are so large that it's not actually as large as it seems to be. Kinda like usb N only working at N-2 speeds...

[bruce511]

Hah - all of those examples use a planet as comparison. The first 16 bits of the address should be reserved to be used by the Planetary Internet Addressing Council (PIAC)

Allocating all addresses to Earth seems very shortsighted.

(Some sarcasm should be assumed.)

It doesn't really matter how you explain large-number math to people who are bad at large-number math (aka all of us) - there's always some bright-spark who misses the point.

[rvnx]

Well we could argue that this support for trillions of IP addresses is nice, except that IPv6 does not technically work in interplanetary environments due to various hardcoded timeouts.

The first martians are likely to run their own local network and then use a VPN over DTN for their everyday communications by email (and appear coming from a single IPv6 address).

One good thing though: since most of the humanity’s knowledge is going to be packed in an LLM they won’t really actually need internet to learn about things. But lack of videos may be annoying.

[remram]

I see only one IPv6 timeout, for fragmented packet reassembly, in other words between reception of fragments. So it's a bound on jitter not latency, and I see no reason it couldn't be increased for interplanetary links.

[Dylan16807]

The moon can share with the earth, and anything further away needs special encapsulation to deal with hours or more of latency.

[atq2119]

It's only minutes for the inner planets. But of course that's already enough to require special treatment.

[ta1243]

One problem of ipv6 is proponents saying there are 2^128 addresses.

It's really hard to comprehend how many unusable ipv6 addresses are.

Having more than 2^16 hosts on a subnet is pretty much impossible. Sticking with "grain of sand" units, but using volumes all from wolfram alpha:

There's 2^80 usable IPs in the entire ipvv6 space, because of the /64 subnets. That's plenty. But for every subnet, that's 40 cubic metres unusable for every subnet, and a sphere 1mm wide of usable addresses.

My ISP give me a /48. I have under 30 addressable devices over 3 vlans. I'm using 40 cubic miles of space. A ratio of about 10 trillion:1

But that's nothing. The IP allocators are happy to give a bank a /16, or in your "grain of sand" measurements 30 times the volume of the moon.

To match my unused:used ratio of 10 trillion to one, chase manhattan would need 2^70 devices, which is billions of addresses per cell.

All the space that fanboys go on about is almost all unusable, so the extreme examples don't really help at all.