[OpenStack] How to Create an Internal Network

By default, there is only one network created in an OpenStack project. But for some scenarios, you might need to create several instances and organize them in an internal network. This internal network could be connected to the public Internet through a router (more discussions in this issue). This blog demonstrates how to create such an internal network in an OpenStack project. A corresponding tutorial video could be found at https://www.youtube.com/watch?v=3RmUpWA7U1Q

Creating an Internal Network

1. Visit page Project/Network/Networks after logging in to the OpenStack dashboard.
2. Click the button Create Network above the topology picture, and input a network name. Make sure the option Create Subnet is enabled. In the Subnet tab, specify a subnet name and its network address (e.g., 192.168.0.0/24). Then click the blue button Create.
3. After several seconds, you should be able to see the created network in the topology diagram. Now click the button Create Router, input a name and select internet as its external network.
4. After creating the router, you will see that it is connected to the external Internal. But it has not been connected to the internal network yet. Move the mouse to the router icon in the diagram and there will be a small panel pops up. Click Add Interface and choose the created subnet as the target.

Now an internal subnet has been successfully created. You can select this network now when you create new instances. Such a setup can be used for hosting a Kubernetes cluster, for example: How to Deploy a Kubernetes Cluster Using Kubeadm.