Dual vs. Single Stack

[jenslink]

I'll start working on a new old IPv6 project shortly, and their current plan is to enable dual-stack everywhere and then go from there to IPv6 only in the coming year. From my point of view forcing dual-stack makes more work, think configuration, monitoring, troubleshooting, and should be avoided if possible. So kind of dual-stack where you must, single stack IPv6 where you can and maybe keep IPv4 only for things that have to be replaced in the (near) future anyway.

I think there should be something about this in the book.

[becarpenter]

plan is to enable dual-stack everywhere and then go from there to IPv6 only in the coming year

That seems incredibly optimistic. I've always been a fan of traditional dual stack when there is a large operational IPv4 legacy that will likely take years to clear. On the other hand, going straight to IPv4-as-a-service is a bigger initial workload but at least in theory significantly reduces OPEX.

We do cover this at [1] and [2] but what we really need is a case study in Chapter 7. There is always some confusion, because until IPv4 is truly dead (i.e. for ever, as far as I can see), apps still need to see a dual-stack socket API, but with IPv4-as-a-service there are no native IPv4 packets on the wire so no dual-stack routing. Anyway, how about writing a case study based on your new project?

[1] https://github.com/becarpenter/book6/blob/main/3.%20Coexistence%20with%20Legacy%20IPv4/3.%20Coexistence%20with%20Legacy%20IPv4.md
[2] https://github.com/becarpenter/book6/blob/main/3.%20Coexistence%20with%20Legacy%20IPv4/Dual%20stack%20scenarios.md

[jenslink]

I know of one large enterprise which is really short on IPv4 addresses, including RFC1918. For them, it was a win to move 1000+ printers to IPv6 only and so get free IPv4 addresses.

[buraglio]

We've taken that approach in several places, Jen. Brian is correct, it's pretty optimistic, but it does short-cut and save a LOT of time when it does work. The hill is more steep, but the ride down from the peak is significantly less rocky.

[becarpenter]

Perfect candidate for a case study for chapter 7! Get writing??