A flat network in Neutron describes a network in which no VLAN tagging takes place. Unlike VLAN networks, flat networks require that the physical interface of the host associated with the network be connected directly to the bridge. This means that only a single flat network can exist per physical interface.
Figure 4.3 demonstrates a physical interface connected directly to a Neutron-managed bridge in a flat network scenario:
In Figure 4.3, eth1 is connected to the bridge named brqZZZZ along with three tap interfaces that correspond to guest instances. No VLAN tagging for instance traffic takes place in this scenario.
On the ...