[api]

Why can't you just do all your v6 routing at l3 and skip l2 and NDP? If you were using WireGuard which is l3 then all you would need is a way to manage the routes. Can you make BGP work without l2? I seem to think you can but I've never tried it.

ZeroTier supports a mode where it emulates NDP for v6 and works without having to do multicast or broadcast at all. It does this by embedding its cryptographic hash vl1 addresses into v6 addresses.

[geofft]

Well, I have hardware routers that know about L2, and I'd like to have them do as much routing as possible. I'm running Quagga to advertise my VXLAN routes to my hardware routers, so packets originated on bare metal can reach my virtualized infrastructure and vice versa. I want them to know that if the machine advertising this particular IPv6 subnet is in the same rack, packets can go there and don't have to go to a dedicated gateway for all my VXLAN traffic.

I could run IPv6 on the inside and IPv4 on the outside, sure. I worry this is going to trigger more edge cases than either running IPv6 the way it was intended or IPv4 the way it was intended.