Fernando, That is the recommended approach, that ovirtmgmt bridge not also be used for VMs. This is for the sake of separation of privilege if I understand correctly, and there's no reason that VMs will not be able to communicate using that bridge. Whether or not you tag depends on your network's logical topology. If you don't tag in oVirt manager and your network uses VLANs, then the packets will be treated as belonging to the default VLAN, often ID 1, but certainly not always.