Once a VM is launched, we need to associate it with a network so that other VMs or external users can connect to it. You can assign a fixed or floating IP address to the VM. A fixed IP address is a private IP address that is used for communication between internal OpenStack VMs residing on the same network. A floating IP address is a public IP address that can be used by external hosts or VMs to communicate with OpenStack VMs.

A pool of floating IP addresses must be allocated to a project so that VMs running on that project can claim these IP addresses:  

The figure shows two floating IP addresses allocated to the project. 

Let's see how we can allocate or deallocate fixed and floating IP addresses using the Python APIs.