OpenStack Neutron provides the floating IP service. A floating IP is a public IP address used for communication with external networks. They are not allocated to the instances by default. The user has to explicitly assign to the server a floating IP from pools configured and provided by the OpenStack administrator.
The floating IP is first allocated to a project and afterwards associated with a VM in that project. Once the IP address is associated to the machine, the user can configure security groups. After the IP adress is associated and security group rules are configured for the server, the VM can be reached, publicly, at the assigned floating IP address.
While Fixed IPs are associated to a VM when it's created and remain the same until the server is terminated, the floating IP address is dynamically attached to an instance. When disassociated with the server, the floating IP goes back to the floating IP pool and is available to the VMs within the project.
Even if a VM dies for any reason, the floating IP address will still be available to the project and able to be associated to other servers.
In City Control Panel, there is a Floating IPs page, under Networking, where all floating IP for the project are listed, a floating IP pool (Figure 1). In the control panel, a floating IP address can only be created when the user creates a new server or modifies a server by assigning a floating IP to one of its network ports.
Figure 1. List of Floating IPs
The user can choose to keep IPs in the pool, so the same IP can be reused later. If the user opts for deletion of an IP from the pool, it's likely that the deleted IP won't return the pool later on.
By clicking the user can view more details, edit the router or delete the floating IP (Figure 2).
In View More, the user will be able to view all information associated to that floating IP, as router id, network id, status, etc (Figure 3).
Figure 2. Deleting Floating IP
Figure 3. Floating IP details
When a floating IP is associated to a device, the IP can be disconnected from this device by clicking