On Fri, Jun 19, 2026 at 1:03 PM Gary Sparkes <gary@kisaracorporation.com> wrote:
The clean path would be NPTv6 with ULA for the same exact setup.
It would slot in and work identically to how the IPv4 deployment is today.
Instead of RFC1918, you have ULA addressing. Same concept.
Except with NPTv6 you're doing 1:1 and eliminate PAT.
Of course, if you're single provider, might as well just use prefix delegation, NPT's real shine is the multi-WAN scenario with no upstream routing protocol that sparked off a lot of discussion.
As to changing providers when using prefix delegation, most stuff can auto-update itself, but otherwise it's a simple find/replace exercise in documentation and records when your provider prefix changes as the last half of the address is entirely stable, and the first half is (mostly) provider.
Maybe I need to do a bit more digging as I'm not an expert at IPv6--but aren't ULA addresses basically randomly assigned to hosts based on their NIC HW address and a few other things? A short example from a very large client I manage: They use IPv4 10/8 The next octet is allocated for the state the office is located in "plus 100". So if they open an office in Alabama (22nd state to join the union), it's gonna be 10.122/16. The third octet is assigned sequentially. The first office opened in Alabama is 10.122.0.0/24. The last octet is static. Router at .254, linux server at .250, Windows (ugh) RDP server at .249, workstations are DHCP between .100 and .199, etc... You can give me nearly any IP from this client and I know the device. But ULA gives me: fe80::ae1f:6bff:feb0:3c98/64 What even is that? Their router? A Windows box? Hard-code the address to fe80::122:00000:250/64 (just to know it's a linux server in Alabama) and then set up NPTv6...and update a *ton* of DNS info so the rest of the world can easily get to the correct machines? Again, I'm having to renumber somewhere--either update a bunch of DNS or update a bunch of internal machines when I change ISPs or have a fail-over. At least that's what it always seemed like to me after going through all the 800-page IPv6 tomes over the years. ;) -A