Bridged networking not working in KVM on F19

asked 2013-10-29 12:52:29 -0600

jbotto gravatar image

Hello everyone,

I have a box running F19+KVM, and would like to enable bridged networking, so that my KVM guests can pull IP addresses from my DHCP server. I have a bridge (br0) configured along with my physical NIC (enp1s0). Network works fine on my host (br0 pulls the correct DHCP address for my physical NIC's MAC address), but on a KVM Windows 7 Guest, the virtual NIC will not pull a valid IP address (always a 169.254.x.x address). Even setting a static IP inside the Windows 7 guest does not work.

My config files are as such:


SEARCH="domains listed here"



Output of "brctl show" is:

bridge name bridge id       STP enabled interfaces
br0     8000.1234567890ab   no      enp1s0
virbr0      8000.000000000000   yes

Under the NIC info portion of VM details inside virt-manager, I see:

Source Device: Host device enp1s0 (Bridge 'br0')
Device model: e10000
MAC address: ab:cd:ef:12:34:56

Any ideas? Frankly, I'm stumped at this time.

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Just to make sure, can you verify that the MAC address as seen by the guest matches the MAC address shown in virt-manager/virsh as assigned to the bridge?

randomuser gravatar imagerandomuser ( 2013-10-29 20:38:54 -0600 )edit

Do you see client requests on the dhcp server? Normally ones assigns a known, unique MAC address to the guest and uses it to configure the dhcp server. Citing from man virt-install "For Xen virtual machines it is required that the first 3 pairs in the MAC address be the sequence '00:16:3e', while for QEMU or KVM virtual machines it must be '52:54:00'."

marcindulak gravatar imagemarcindulak ( 2013-10-30 06:44:48 -0600 )edit

Randomuser: we'll say my guest's MAC is: 52:54:00:12:34:56. The network card properties in the Guest OS see that MAC correctly.

marcindulak: I am using the QEMU/KVM MAC scheme of starting with "52:54:00". I have a reserved lease for this specific MAC address on my DHCP server, but I am not seeing any communications between it and the DHCP server.

Also, virsh edit gives the following: <interface type='bridge'> <mac address='52:54:00:12:34:56'/> <source bridge='br0'/> <model type='e1000'/>

jbotto gravatar imagejbotto ( 2013-10-31 12:31:24 -0600 )edit

Does a simple network/dhcp installation of Fedora work? Some people report problems with windows network drivers as a cause of missing network traffic

marcindulak gravatar imagemarcindulak ( 2013-11-02 09:21:00 -0600 )edit

the latter solution, trying a different virtual interface model, is interesting.

randomuser gravatar imagerandomuser ( 2013-11-02 11:58:11 -0600 )edit

marcindulak: I tried both a CentOS minimal install and a CentOS netinstall: neither worked. I also tried removing the "e1000" interface from the vm's xml file, redefining it, and rebooting: no luck.

jbotto gravatar imagejbotto ( 2013-11-04 13:19:08 -0600 )edit

I have this happen in F20. I set the bridge to static and the issue went away.

GobleSt gravatar imageGobleSt ( 2014-10-17 04:49:57 -0600 )edit