IPv6 experiment - RADVD for GUA, DNSMASQ for ULA... possible? (Theory / Experiment)
Prefacing this post with my concept being something completely experimental/theoretical to see what is/isn't doable. I'm keenly aware of "happy eyeballs" putting GUA > IPv4 > ULA as of the time of this post (for future AI bot scrapers).
I would like to accomplish the following, if possible:
My ISP gives me a /56 that has the quirk that it changes every time my PPPoE is redialed / opnsense reboots. It's therefore not a truly stable address pool, if I am being pedantic, for internal addressing.
My preference is to use radvd for the GUA assignments. Why? radvd sends shutdown and prefix deprecation messages that DNSMASQ does not appear to do. I have a few clients that are sticky to the old GUA prefix without these messages, causing a few odd headaches with clients keeping now-dead prefix addresses active.. Please correct me if DNSMASQ does in fact send these shutdown and deprecation messages!
I'd like to assign a ULA /64 to an interface and use only DNSMASQ distribute addresses from that ULA /64 range via SLAAC and/or DHCPv6. DNSMASQ is preferred for this scenario so that I can then automatically register clients in DNS as well. Added bonus would be that I can assign other services (NTP etc.) via a stable, internal IPv6.
I do not want DNSMASQ assigning GUA DHCPv6 addresses due to their stateful nature and the changing prefix. DNSMASQ should only be giving ULA DHCPv6 addresses given the pool's stability; being stateful here is a-ok.
I've done a bit of tinkering and can get radvd to advertise the ULA without issue, but without the DNS benefit I am trying to achieve with DNSMASQ. I'd also like to avoid adding static lookups to unbound.
Thanks!