Comment by infogulch

I think it would be neat if headscale allowed peering / federating between instances. (Maybe after the ACL rework.) One of the main problems is address collisions.

So here's my proposal: commit to ipv6-only overlay network in the unique local address (ULA) range, then split up the remaining 121 bits into 20 low bits for device addresses (~1M) and 101 high bits that are the hash of the server's public key. Federate by adding the public key of the other instance and use policy and ACLs to manage comms between nodes.

I think it's a nice idea, but the maintainer kradalby said it's out of scope when I brought it up in 2023: https://github.com/juanfont/headscale/issues/1370