An Enterprise IPv6 Address Planning Case-Study
Why Hacker News recommends it
HN commenters cite it as an accessible introduction to IPv6 address planning (subnetting at /64, site allocations) and as the source of the stars-versus-addresses comparison for the size of the IPv6 space.
Recommended by 2 people across 3 different months, 2021 to 2026.
What it is
Tom Coffeen, author of O'Reilly's IPv6 Address Planning and an Infoblox IPv6 evangelist, presents a real-world enterprise IPv6 address plan. He covers the principles of address planning for corporate IT networks and options for IoT, containers/microservices, and cloud.
What people said
Strong rec kemotep · 2022-08 · Hacker News · on “Simple IPv6 Subnet Auto-Configuration”
This doesn’t seem as simple as sticking your IoT devices behind a /64. Your site should be assigned at least a /56 from your ISP giving you 255 possible /64s. If you need more subnets you need to get a /48 from your provider. And if 2^16 subnets for your IoT devices is insufficient you will need to go to your Regional Internet Registry to get more. I see this is to avoid issues with Neighbor Discovery Protocol and isolate hosts but to call this simple when you already will need to deploy a security solution(s) beyond subnetting to enforce your network policies is what I take issue with. IPV6 address planning and security is not the same as IPV4. This talk[0] is an hour long but from 22:18 on
Recommends throw0101a · 2021-08 · Hacker News · on “India is leading IPv6 migration with 61.67% adoption”
> 128bit per address from which usable only 64bit looks like a waste of resources (CPU/RAM) to me. I would recommend you check out Tom Coffeen, who wrote a book on IPv6 address planning for O'Reilly. Even with half the bits going to the subnet, there is a astronomical amount of addresses available: * [this video]
Recommends throw0101a · 2025-01 · Hacker News · on “IP addresses through 2024”
> I feel like this blog does not accurately describe how large the ipv6 address space even after accounting for it being reduced by 2^64 for the host portion of the address. One way of thinking about it: * Stars in the Milky Way: 400 Billion * Galaxes in the universe: 2 Trillion So (4x10^11)x(2x10^12)=8x10^23 stars in the universe. * Size of IPv6 address space: 3.4x10^38 Find the ratio between addresses and stars: * 3.4x10^38 / 8x10^23 IPv6 offers about 430 trillion times more addresses than estimated stars in the universe. From Tom Coffee's presentation "An Enterprise IPv6 Address Planning Case-Study" * [this video] Perhaps in more human terms: on the surface of the Earth (including oceans), the
Cites throw0101a · 2021-08 · Hacker News · on “IPv4 vs. IPv6 FAQ”
Another way of thinking about it: * Stars in the Milky Way: 400 Billion * Galaxes in the universe: 2 Trillion So (4x10^11)x(2x10^12)=8x10^23 stars in the universe. * Size of IPv6 address space: 3.4x10^38 Find the ratio between addresses and stars: * 3.4x10^38 / 8x10^23 IPv6 offers about 430 trillion times more addresses than estimated stars in the universe. From Tom Coffee's presentation "An Enterprise IPv6 Address Planning Case-Study" * [this video]
Cites throw0101a · 2022-05 · Hacker News · on “460M Indian Internet Users Are Now on IPv6”
Another way of looking at it: * math property: x^y = x^(a+b) = (x^a)x(x^b) * IPv4 addresses are 32 bits (2^32) * 2^32 ~ 4.3 billion * So the IPv4 Internet has ~4.3B devices on it * IPv6 subnets are 64 bits, /64 (2^64) So, a IPv6 2^64 subnet is the same as (2^32)x(2^32), which means (4.3B)x(IPv4 Internet). I.e., a single IPv6 subnet can hold the equivalent of four billion (IPv4) Internets. -- A second way of thinking about it: * Stars in the Milky Way: 400 Billion * Galaxies in the universe: 2 Trillion So (4x10^11)x(2x10^12)=8x10^23 stars in the universe. * Size of IPv6 address space: 3.4x10^38 Find the ratio between addresses and stars: * 3.4x10^38 / 8x10^23 IPv6 offers about 430 trillion ti
Cites throw0101a · 2022-10 · Hacker News · on “Your First IPv6 Request”
> I get a dynamic /64 prefix from my ISP at home, which would be large even if it were assigned to my work office; why is the maximum prefix length /48 for a single site and /32 for 3k sites? The default subnet size for IPv6 is /64, and a single "site" is /48. There are 16 bits between those. Comparing with IPv4, where a 'typical' subnet is /24, if you were given 16 of space to play with as you see fit, you'd be assigned a /8—i.e., an entire Class A. (Which is what most companies use now anyhow—i.e. 10/8—and then have to futz around with NAT.) So a 'typical' IPv6 allocation is as many IP addresses as what some of the largest corporations have. Plus all of those addresses are available for us
Cites throw0101c · 2026-10 · Hacker News · on “If IPv4 were land”
Ran across a comment a while ago on some fun "IPv6 math": On the surface of the Earth [land+water], there are 8.4 IPv4 addresses per km². Not counting the oceans, that would be 28 IPv4 addresses per km² land. IPv6 gives 10¹⁷ addresses per mm² (yes, square millimetre). In terms of volume, 10⁸ IPv6 addresses per mm³ throughout the Earth. * Via: [LINK] A second way of thinking about it: * Stars in the Milky Way: 400 Billion * Galaxies in the universe: 2 Trillion * So (4x10¹¹)x(2x10¹²) = 8x10²³ stars in the universe. * Size of IPv6 address space: 3.4x10³⁸ * Find the ratio between addresses and stars: 3.4x10³⁸ / 8x10²³ IPv6 offers about 430 trillion times more addresses than estimated stars in th