[libvirt-users] Remove Virtual bridge and DNSMASQ

mimicafe at gmail.com mimicafe at gmail.com
Fri Apr 24 18:12:54 UTC 2015


On 24 April 2015 at 18:00, Laine Stump <laine at laine.org> wrote:

>  (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 at 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 at redhat.com> wrote:
>
>> On 24.04.2015 12 <24.04.2015%2012>:45, mimicafe at 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.
>
>
>  The problem of top-posting is from the way reply is composed within
Gmail. I'll watch out next time.

Thanks

Mimi
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