Rafael, re your last email - this is only saying that CLoudStack Public network can have either "a real public / publicly routable" IP address range, or some other private Ip range - but both of those are, so to speak, external to CloudStack - and whatever the IP (range) defined fort the cloudstack "Public" network - those IP (be it really public or private) will be attached to VR only.
Using Isolated network offering - has NOTHING to do with the "public" network. The Isolated network is a network on VR's internal interfaces, between the VR and VMs in that Isolated, while the CloudStack "public" network is the network/IP of the external NIC (publicly facing NIC) of the VR. Let me know if you need more clarification Best,
