It's the Red network in the diagram.
Represented as the red network in the above diagram, the Public Network is the one to access the Internet from the Cloud Cluster. In this scenario we have configured the network in such a way that virtual machines can access the Internet. The servers in the Management network can access the Internet too.
It is recommend that some level of Quality of Service (QoS) system is implemented to guarantee the minimum amount of bandwidth required to access the Internet.
If you are building a Public Cloud you can implement a different configuration, where the Public Network and the Cloud Cluster Network are the same.
