A public network is used to connect to other networks or the Internet. A public network has few or no restrictions, so consider possible security risks when you access it. There is no technical difference between a private and public network in terms of hardware and infrastructure, except for the security, addressing, and authentication systems you use.
You can use the GUI to combine public networks into a single public cloud. For more information, refer to Working With Public Clouds in Oracle Fabric Manager 5.0.2 Administration Guide.