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by skissane 319 days ago
Why run your K8S cluster on IPv6 when IPv4 with 10.0.0.0/8 works perfectly with less hassle? You can always support IPv6 at the perimeter for ingress/egress. If your cluster is so big it can’t fit in 10.0.0.0/8, maybe the right answer is multiple smaller clusters-your service mesh (e.g. istio) can route inter-cluster traffic just based on names, not IPs.

And if 10.0.0.0/8 is not enough, there is always the old Class E, 240.0.0.0/4 - likely never going to be acceptable for use on the public Internet, but growing use as an additional private IPv4 address range - that gives you over 200 million more IPv4 addresses
2 comments
lmm 318 days ago
> Why run your K8S cluster on IPv6 when IPv4 with 10.0.0.0/8 works perfectly with less hassle? You can always support IPv6 at the perimeter for ingress/egress.

How is it "less hassle"? You've got to use a second, fiddlier protocol and you've got to worry about collisions and translations. Why not just use normal IPv6 and normal addresses for your whole network, how is that more hassle?

> You can always support IPv6 at the perimeter for ingress/egress. If your cluster is so big it can’t fit in 10.0.0.0/8, maybe the right answer is multiple smaller clusters-your service mesh (e.g. istio) can route inter-cluster traffic just based on names, not IPs.

You can work around the problems, sure. But why not just avoid them in the first place?

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skissane 318 days ago
> How is it "less hassle"? You've got to use a second, fiddlier protocol and you've got to worry about collisions and translations.

Because, while less common than it used to be, software that has weird bugs with IPv6 is still a thing-especially if we are talking about internally developed software as opposed to just open source and major proprietary packages. And as long as IPv6 remains the minority in data centre environments, that’s likely to remain true - it is easy for bugs to linger (or even new ones to be introduced) when they are only triggered by a less popular configuration

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lmm 318 days ago
True, but already the newest software has good IPv6 support, and that suggests a tipping point should be coming where as soon as the majority is on IPv6 it becomes in everyone's interest to get off of IPv4.
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paulddraper 318 days ago
Are you responding to the right comment?

My point was that NAT is for IPv4 address exhaustion.

There’s no point to using NAT for IPv6.

If your software doesn’t work with IPv6, and you need IPv4…that is subject to IP address exhaustion. So yeah you need NAT for IPv4.

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