Create a Host Bridge Using virsh



Failed to add tap interface to bridge 'br0': No such device

Solution

Either use "virsh edit $guestname" to change the <interface> definition to use a bridge or network that already exists (e.g. change "type='bridge'" to "type='network'", and "<source bridge='br0'/>" to "<source network='default'/>", or add the given bridge device to the host system configuration.

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Create a Host Bridge Using virsh

If you have libvirt >= 0.9.8 and your distro supports the virsh iface-* commands (e.g. RHEL and Fedora) a bridge device can be created in one easy step with the "virsh iface-bridge" command. The following command will create a bridge device "br0" that has interface "eth0" attached:
  virsh iface-bridge eth0 br0

You can later remove this bridge and restore the original eth0 configuration with:
  virsh iface-unbridge br0

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Create a Host Bridge Manually

For older versions of libvirt and other OS distros that don't support the virsh iface-*, you can manually create a bridge device on the host using these instructions.
 
Retrieved from "http://wiki.libvirt.org/page/Unable_to_add_bridge_br0_port_vnet0:_No_such_device"