Networking
Basics
You can see the current network of your project from the Juno webpage. There you see the three basic networks available to all projects: <myproject>_network , where you VM lands by default, it is the local area network (LAN) of your project; the Public-Network that is the internet, you see that a router named <myproject>_router is connecting your LAN to the internet; CephFS-Network is the CephFS file system network; you need to connect your VM to that network to access CephFS volumes.
There could be situations where it is needed to share a network with the project of a collaborator on SD4H so communication between two servers can be done without having to resort to the internet.
Create a new network
You can create a network from the Create network button from both the Network Topology tab. Pick the name of the network with Enable Admin State and Create Subnet box checked, click next, pick a name for the subnet, in Network Address Source select Allocate Network Address from a pool , select the 172.16.0.0/12 pool and use the needed Network Mask , 24 will give you 256 addresses, click Next, make sure Enable DHCP is checked and click Create. You now have a new network. You can attach an existing VMs to that new network in the Instance tab by selecting Attach Interface in the Actions drop down menu of the instance.
Not that VMs that will be solely attached to that network will have no internet access. You would need to attach the router that has access to the Public-Network to the network to make that happen.
This step can only be made with the OpenStack Client, start by following its installation and configuration procedure