Configuring Inter-VDOM routing over IPsec

[kzuk]

This is diagram of my infrastructure: VDOMs Public have internet access, VDOMs Secure not.   For now VPN IPsec work correctly but only between VDOMs Public. Generally the current configuration works as in the diagram but I have problem with connect VDOMs Secure over IPsec. So my questions is:

[ul]

How should I configure Inter-VDOM routing to connect VDOMs Secure over IPsec?

How should I configure Inter-VDOM routing to connect each VDOM with each other over IPsec?[/ul]

Both devices is FortiGate 100E.