In Nova, users organize their cloud resources in projects. A Nova project consists of a number of VM instances created by a user. For each VM instance, Nova assigns to it a private IP address. (Currently, Nova only supports Linux bridge networking that allows the virtual interfaces to connect to the outside network through the physical interface. Other virtual network technologies, such as Open vSwitch, could be supported in the future.) The Network Controller provides virtual networks to enable compute servers to interact with each other and with the public network.
Currently, Nova supports three kinds of networks, implemented in three “Network Manager” types respectively: Flat Network Manager, Flat DHCP Network Manager, and VLAN Network Manager. The three kinds of networks can co-exist in a cloud system. However, the scheduler for selecting the type of network for a given project is not yet implemented. Here is a brief description of each of the different network strategies, with a focus on the VLAN Manager in a separate section.
Read more about Nova network strategies here:
Admins and Network Administrators can use the ‘nova-manage’ command to manage network resources:
[network_size=FLAG], [vlan_start=FLAG], [vpn_start=FLAG]
network modify: Associate/disassociate network with project and/or host.
network delete: Deletes a network. Precisely one of --fixed_range or --uuid must be specified.