In Neutron, it is easy to create many private networks that allow communication between your instances. Sometimes, you might require certain features of a particular network such as when utilizing a dedicated 10G interface; creating a VLAN network to operate with a physical network device, for example, a load balancer; or a SQL Server cluster. With Neutron's SDN, an administrator can set up networks to cater for these purposes.

The following figure shows an example environment with another interface that we can use within Neutron. The physical SQL servers in this environment could be on a Subnet of 192.168.200.0/24 on VLAN 200. To use to this network from within OpenStack, we can specify another interface, eth4, that will be used to connect OpenStack Virtual instances to physical servers using this same subnet and VLAN.

The network on eth4 can be configured for a number of different VLANs as you would expect on this type of network.