OVN provides virtual networking for Open vSwitch and is a component of the Open vSwitch project. This project provides integration between OpenStack Neutron and OVN.
The original OVN project announcement can be found here:
The OVN architecture is described here:
OVN includes a tutorial to help with understanding how it works:
OVN DB schemas and other man pages:
The openvswitch web page includes a list of presentations, some of which are about OVN:
These blog resources may also help with testing and understanding OVN: