To configure the Compute node's networking for the VM images, the overall steps are:
Set the
network_manageroption in nova.conf.Use the
nova-manage network create label CIDR n ncommand to create the subnet that the VMs reside on.Integrate the bridge with your network.
By default, Compute uses the VLAN Network Mode. You choose the networking mode for your virtual instances in the nova.conf file. Here are the three possible options:
--network_manager=nova.network.manager.FlatManagerSimple, non-VLAN networking
--network_manager=nova.network.manager.FlatDHCPManagerFlat networking with DHCP, you must set a bridge using the
flat_network_bridgeoption--network_manager=nova.network.manager.VlanManagerVLAN networking with DHCP. This is the Default if no network manager is defined in nova.conf.
When you issue the nova-manage network create command, it uses the
settings from the nova.conf configuration options file. Use the following command to
create the subnet that your VMs will run on :
nova-manage network create private 192.168.0.0/24 1 256
When using the XenAPI compute driver, the OpenStack services run in a virtual machine. This means networking is significantly different when compared to the networking with the libvirt compute driver. Before reading how to configure networking using the XenAPI compute driver, you may find it useful to read the Citrix article on Understanding XenServer Networking and the section of this document that describes XenAPI and OpenStack.

