On 09/18/2010 04:52 PM, Glynn D. Reynolds wrote: That error would not be encountered while parsing the XML in /etc/libvirt/network/default.xml - that file is parsed by the virtual network parser (virNetwork*) not the host interface parser (virInterface*), and changing it would have no effect here (note that, in any case, you should never edit that file, or any other file in /etc/libvirt directly - always go through the *-edit commands provided in virsh). You are apparently attempting to define a host interface (with "virsh iface-define" or by calling virInterfaceDefineXML()), or possibly retrieve the XML for an existing host interface (with "virsh iface-dumpxml" or virInterfaceGetXMLDesc()). Please tell us what you are doing (and what the inputs are) when you encounter this error - either the XML you are providing to iface-define is incorrect, or the XML of and existing interface produced by the netcf library is incorrect.