Hello there. I has an ISP routed ONU delivering DHCPv6-PD. Before acquired rb750GR3, i was using a TPlink router with IPv6 passthrough to connect my devices and all were able to acquiring IPv6 like an DHCPv6 statefull mode.
Now with RouterOS i found no way to achieve a way to connect my hosts. When requesting prefix it keep searcing endless. If i try request only address then RouterOS receive an IPv6 address from ISP ONU,
Through RouterOS hosts are even receiving an temporary IPv6 and DNS but cant connect to gateway fe80::1
If it gives you address but not prefix, then it doesn’t look like DHCPv6-PD, only DHCPv6. With current RouterOS it’s a problem, because it would need ND proxy and RouterOS doesn’t have it. You can bridge everything together and demote the router to switch, but that’s far from ideal.
In fact, dhcp-client address request gets an strange address which looks prefix, 2804:xxxx:yyy:zzzz::2 with fe80::1 server. Calling for prefix only, it keeps searching endless.
ISP guy showed me this image of their ONU config, looks DHCPv6-PD is enabled.
Well, “IPv6 Prefix Mode: Prefix Delegate” does sound like it could be it, but it can also be config for that device, what it should get from upstream. And other things suggest that it’s not for downstream. First is that RouterOS doesn’t get any prefix.
Second is that you needed IPv6 passthrough config with TP-Link. No kind of passthrough is necessary with properly configured prefix delegation. With that, you get assigned your own prefix from DHCPv6 server, your LAN gets /64 from that, devices in LAN have router’s address as gateway, etc.
Even the rest of screenshot suggests that the device is working as router (“WAN Enable: Enable”, “NAT: Enable”, “WAN IP Mode: PPPoE”, IPv4 address, everything). The right config is that this device would be completely transparent, it wouldn’t assign any addresses, both IPv4 and IPv6, PPPoE client would be on your own router, etc. My guess is that the “Connection Type: Route” should have another option called bridge or something like that, and that’s what you want.
You should be sure about this settings being what ONU take from upstream, so that DHCPv6-PD is not for my router. I’ve already know than the ONU is routed, its has private IP range which im connected through WAN to it.
Problem is than this ISP dont give access or modify ONU settings, bridge mode is a “no way” for them. So i was searching if there is a workaround with ROS for that. What i will try now is find if there is a DHCPv6-PD option for downstream in their ONU to activate, since they say both DHCP are disabled, because i requisited DHCPv4 being turned off in past.
Proper workaround (which is already wrong) is ND proxy. Current RouterOS doesn’t have it. There’s no doubt they will add it eventually. They will have to, because too many ISPs got IPv6 wrong and it’s needed. Unfortunately, no one can tell when will it happen.
Without it, you’d have to do something with bridge, but the problem is that you’d need only IPv6 bridged, not IPv4. But by default bridge affects everything. Something may be possible with bridge filters, but it’s far from ideal. How exactly you get IPv4 (static config, PPPoE, …)?
You could bridge ether1 with ether3-5 and do something with either bridge filters or bridge’s “Use IP Firewall” option. You could have common subnet with ONU for both IPv4 (you’d have one less NAT) and IPv6, and use router as transparent firewall, so your network would be still protected.
Thats work for IPv6, but i loose access to second ISP PPPoE link. My primary config with both links were a simple mangle prerouting splitting two /25 for each link, so i leaved my DHCP at .128 range to connect mobile devices to secondary link. I have no clue what to do now to keep second link usable through ONU network.
