[libvirt-users] libvirt bridge configuration

Laine Stump laine at laine.org
Mon Jan 31 13:25:45 UTC 2011

On 01/31/2011 12:18 AM, Justin Clift wrote:
> On 31/01/2011, at 5:52 AM, Taras Lipatov wrote:
>> Hi Every one,
>> I'm hoping some one can point me in the right direction.
>> We are piloting KVM + Libvirt for migrating off Xen and I'm stuck with the network bridge configuration via libvirt.
>> What we have currently with xen is:
>> 1 server with Wan/lan interfaces and a pool of public ip addresses.
>> Using xen bridge scripts I'd start a xenbr0 and attach eth0 (wan) and go ahead and assign public IP's
>> to images attached to xenbr0.
>> Now with creating virbr0, I need to assign it an ip address? and routing methods? what about creating a transparent bridge via libvirt?
>> I kno I can achieve this using bridge utils, but it would be nice to have everything handled by libvirt.
>> Any help would be appreciated.
> Hi Taras,
> Is this helpful at all?
>    http://wiki.libvirt.org/page/VirtualNetworking
> I'm thinking the "Routed" mode there might be what you're looking for?

Actually, since he's talking about attaching eth0 to the bridge and the 
guests having public IPs, I'm thinking he's talking about what we call 
"bridged mode", which is covered starting here:


(Note that recent libvirt does have an API to configure any host network 
interface, including a bridge that's attached to a physical interface 
(look for the "iface-*" commands in virsh), but that API depends on the 
netcf library, which so far is only available on RHEL and Fedora 
platforms, so if you're running on something else, you'll need to follow 
the manual instructions at the provided link for setting up the bridge).

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