How to map Acquired IP form the cloud?

I use CloudStack Cloud environment and to expose a VM that is running in the cloud on internet I need to "acquire" a public IP address from an aviable network.
This Address is not a new NIC of the machine but is used to port forward, on specific ports, the traffic.
How do I map the acquired IP? is not a Port since is not a NIC.
My idea is to use a relation between the Compute node and the Network Node.
Obviously I need to declare the network node as "external" (see my previous issues) since the orchestrator does not have to "create" that network but just use it in the process of getting the IP.
Another option, probably more easy to implement is to create an IP node since that will be easier to implement and than relate it to network and Compute.