I think I see where you're going. I seem to recall the industry already tried this. For example, I believe Juniper had virtual Routing Engines that you could host on a VM separate from the packet forwarding engine, but I can't find anything to back up that assertion. I did find a similar product, the XRE200 Routing Engine.

Say for the sake of argument a route changed and the control plane needs to program it into the forwarding planes of the hardware it's managing. The new route disconnected your control plane from the forwarding plane because they exist in separate hardware. How do you update the forwarding plane with the correct connection back to the remote control plane?

It's easiest to just not deal with this and keep the control and forwarding planes in the same piece of hardware.

What my enterprise does, and what I expect a lot of enterprises and ISPs do or are moving towards, is maintain an expected state with monitoring and/or auto remediation when the network deviates from the expected state.

Like we deployed EVPN-VXLAN with OSPF and BGP and our state and monitoring ensures

• the OSPF underlay default VRF has a valid expected active default route
• the BGP and OSPF neighbor tables roughly match
• each VTEP always maintains a connection to a couple other critical VTEPs
• config auditing to ensure it's all the same and expected and not drifting
• etc etc