(in before Eric for this :-) Please don't top-post in responses on this list (or most other technical lists). Posting your responses in the context of the previous message makes it much easier for followups that want to respond to points from several messages at once (and also makes it easier to understand the discussion by reading just one of those messages).

On 04/24/2015 11:08 AM, mimicafe@gmail.com wrote:

HI Michal

Thank you for explaining. I have this situation in a number of production servers where we would always use static IPs for the host and VMs. In such  case we have no requirement for NATed network in the future. And we we ever do, we can rely on a DHCP server within the LAN to provide IPs to the VMs.

I'll look to remove both  libivirt-daemon-driver-network, libvirt-daemon-driver-network and dnsmasq.

You can't remove libvirt-daemon-driver-network, as libvirt-daemon-driver-qemu is dependent on it (for very good reasons). If you try to do this, you will almost surely end up with a crashing libvirtd.

Any further thought from your side?

On 24 April 2015 at 13:12, Michal Privoznik <mprivozn@redhat.com> wrote:

On 24.04.2015 12:45, mimicafe@gmail.com wrote:
> I am running KVM virtualization with libvirtd (libvirt) 0.10.2  in bridged
> network mode, however I still have the default virtual network
> bridge/interfaces and dnsmasq on the host. What I am trying to understand
> is whether or not dnsmasq and the virtual network (*virbr0, Vnet0 and Vnet1*)
> still play any role. If not, can I remove them?

You are mixing together a couple differnet (but related) things. virbr0 is a bridge device created for libvirt's "default" virtual network, and the dnsmasq instance that is running is also run by libvirt for that network. However, the vnet0 and vnet1 devices are tap devices; one of these is created for each domain interface, whether you use libvirt's network or you connect to a host bridge that you've configured yourself - you can't eliminate those devices.

Yes, you can safely remove libvirt-daemon-config-network package. It
should disable the default network.

Actually that won't disable any already-installed default network. You'll need to do this:

    virsh net-destroy default
    virsh net-undefine default

Once you've done this, the virbr0 device will no longer appear, and dnsmasq will not be run (although the binary will still be present on the disk).

However, dropping dnsmasq is a bit
harder, since libivirt-daemon-driver-network depends on it. We can't
know whether you will not someday like a NATed network with a DHCP
server, even though now you don't. However,
libvirt-daemon-driver-network takes care about all the network types
known to libvirt, so you can't really drop it (unless forcibly removing
the package and let the libvirt just deal with it, which I'd discourage
you from doing anyway).

That's not going to work. There are things in the network driver other than just libvirt's virtual networks, and qemu isn't setup to deal with the network driver not being present.