[libvirt-users] changue bridge name, libvirt refuses to take new name

Eric Blake eblake at redhat.com
Mon Sep 26 18:37:32 UTC 2011

On 09/26/2011 10:42 AM, Sergio A. Kessler wrote:
> - edited /etc/libvirt/qemu/rmdev2.xml and changed the line<source
> bridge='br0'/>  to<source bridge='br1'/>

Wrong.  You should not be directly editing anything under /etc/libvirt, 
but instead should be using 'virsh edit rmdev2' to make those changes. 
It may be because you went behind libvirt's back that your edits were 
not recognized, and that you had to end up undefining and re-creating a 
new guest before you got this to work the way you wanted.

> # brctl show
> bridge name     bridge id               STP enabled     interfaces
> br1             8000.e41f13ba6e1a       no              eth1
> virbr0          8000.5254003a3124       yes             virbr0-nic
> # virsh -c qemu:///system start rmdev2
> error: Failed to start domain rmdev2
> error: Failed to add tap interface to bridge 'br0': No such device
> there *nothing* 'br0' in /etc in the system (I grepped it),
> why is looking for br0 instead of br1 ?

One other thing to check, although I'm not sure it matters in your case 
(since you said that creating a new domain worked): when modifying 
network information, you may also need to modify libvirt's notion of the 
network, via such commands as 'virsh net-list' and 'virsh net-edit'.

Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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