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by oxplot·4y ago·view on hn ↗
> CGNAT itself is a enormous risk.

How?

IPv6 isn't a substitution for CGNAT, it's an addition to it. You either have to keep CGNAT or replace it with dedicated IPv4 for each customer. Dedicated IPv4 is most likely too costly given the limited availability. SpaceX is also trying to cut cost aggressively.

3 comments
It’s stateful.

Specifically, if a plain router stops working, BGP will route around it, and all you did was drop packets. If NAT stops working, you don’t just drop packets, you drop whole connections. Applications don’t tend to tolerate dropped connections as well as they tolerate dropped packets.

True. As an ISP you are gonna need an IPv4 stack no matter what. Even if that stack is CGNAT'd up the ass. I can't even ping news.ycombinator.com or amazon.com with IPv6.

That is the biggest problem with IPv6. Who is gonna be the first ISP to shut off their IPv4 stack? There is always gonna be some random website that is IPv4.

When all the big services become IPv6, the number of IPv4 megabits will become small.

You might just direct all the v4 traffic via a tunnel to another ISP which specializes in legacy services like IPv4, running SMTP/news servers, etc. Now you've saved all the cost of maintaining all the IPv4 peerings and config.

>When all the big services become IPv6, the number of IPv4 megabits will become small.

Well I have been hearing about the end of IPv4, and IP exhaustion for about 20 years now, and I fully expect people to still being moaning about it 20+ years from now while the majority of the interment still communicates over ipv4

Amen. I dual stacked my home network 10 years ago. 5 years ago I joined an ISP that gave me CGNATv4 and IPv6 and I opted to disable IPv6 at the router.
Why? If you have an IPv4 address, even a dynamic one, then IPv6 may not offer you a lot of practical benefit, but CGNAT-only sucks if you're at all technical.
It sucks if you're non-technical too, it's just harder for non-technical users to figure out the underlying source of any problems they have.

v6 also has better measured performance on webpage load times. Perhaps "pages load slightly slower than they could do" isn't a show-stopping problem, but faster would still be better, right?

CGNAT specifically means you can't have even temporary peer-to-peer connections, e.g. non-server multiplayer games generally won't work. And forget about trying to host anything, dynamic DNS services can't help you here. That to me is a much bigger problem than IPv4 in general being a bit slower.
It's a partial substitution. What percent of your traffic is youtube, for example?