Gianpiero,
This is a question we are frequently asked, as this is a pretty common requirement. We do support multiple subnets on a target. The network that will be used for NFS is determined by the host address given when adding the environment (this network will also carry SSH traffic between Delphix and the target). So, configure the environment using the NFS VLAN address.
When we discover the environment, we will pick up the listeners on the other network(s), and we will register VDBs to those listeners, making them available on that network.
For the "Delphix VLAN" in this diagram, you would need to have a listener on this network in order for Delphix to use it for JDBC connectivity to the VDB.
Please let me know if you have any further questions.
Thanks,
Michael