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jpdb01/02/20265 repliesview on HN

That particular benefit has no value if you still need to support v4.

It's almost a self-inflicted tragedy of the commons or reverse network-effect.

Adopting IPv6 doesn't alleviate the pain of IPv4 exhaustion if you still need to support dual-stack.


Replies

craftkiller01/02/2026

It still helps. I have a 1U in a colo which gives me a /64 for ipv6 and ~5 addresses for ipv4. I just set up a dual stack kubernetes cluster on 6 virtual machines. When I want to ssh into one of the machines, my options are either:

  1. Use IPv6 which works and goes directly to the virtual machine because each virtual machine grabs its own address from one of my 18446744073709551616 addresses.
  2. Use IPv4 and either have to do a jumphost or do port forwarding, giving each virtual machine its own port which forwards to port 22 on the virtual machine.
  3. Use a VPN.
I have all 3 working, but #1 was significantly less setup and works the best.

Also being able to generate unique ULA subnets is super nice.

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est3101/02/2026

If you are an ISP running dual stack ipv4 with NAT plus ipv6, the more connections happen via ipv6 and the more traffic happens via ipv6, the better, because it doesn't have to go through the NAT infrastructure which is more expensive, and cost scales with traffic (each packet needs its header to be modified) and number of parallel open connections (each public v4 address gives you only 65k port numbers, plus this mapping needs to be stored in RAM and databases).

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throw0101alast Saturday at 2:49 PM

> Adopting IPv6 doesn't alleviate the pain of IPv4 exhaustion if you still need to support dual-stack.

Sure it does: the more server-side stuff has IPv6 the fewer IPv4 addresses you need.

If you have money (or were around early in the IPv4 land grab) you have plenty of IPv4 addresses so can give each customer one to for NATing. But if you don't have money to spend (many community-based ISPs) you have to start sharing addresses (16:1 to 64:1 is common in MAP-T deployments). You also have to spend CapEx on CG-NAT hardware to handle traffic loads.

Some of the highest bandwidth loads on the Internet are for video, and Youtube/Google, Netflix, and MetaBook all support IPv6: that's a lot of load that can skip the CG-NAT if the client is given a IPv6 address.

If you can go from 1:1 to 16:1 (or higher) because so few things use IPv4 that means every ISPs can reduce their legacy addressing needs.

Dagger2last Saturday at 12:42 AM

On company/university wifi networks, v6 cuts your v4 DHCP pool address usage by something like 70%, without hurting connectivity to v4 hosts.

patmorgan23last Saturday at 6:05 PM

You can run a V6 first network with a tiny bit of v4 sprinkled in on the edge where it's needed. The tech to do this is mature and well understood.