Sanity check: ULA's for small business with 4 isolated subnets.
I am the admin for a small business with 4 isolated subnets that only talk to each other over the public internet.
There is no multihoming and each subnet has a static, public, ipv4 address. Sites are linked together with VPNs.
Our internal network is currently ipv4 only and I am looking to move to a dual stack network internally at all 4 sites.
This will be my introduction to ivp6 so I've been doing my reading and believe I need to setup ULA's in my network, but in my looking around online, those are contentious so I want a second opinion before I proceed.
My ISP does give me /56 prefix for my router to hand out GUAs to my internal network devices at all 4 sites.
But the two things that make me believe I need to also setup ULAs are:
-Internal DNS server that is not the router. From what I read, to use an internal DNS server for private, internal, DNS entries, you need ULA in order to be able to set a static IP to be handed out for the DNS server.
-I will not be able to register directly for a public ipv6, so I am dependent on my ISP's /56 they give me being static (well, unchanging) and I'm not sure I trust that. So I setup ULA's internally and then just have to update the routing (hopefully in one location per site) if the /56 my ISP gives me ever changes.
So, what are your thoughts? From a network design perspective anyways.
Do I need ULA's, or did I miss something and GUA's would suffice for my situation?
EDIT: To clarify, I meant running ULA internally along with GUA addresses, I am not talking about NATing my ULA addresses out to the public internet.