[libvirt-users] How libvirt interacts with dhcpd?

[Daniel.]

Thanks for your help Laine
In my case disabling dhcpd is not an option so I took the path of disabling
dhcp on virbr0. Pxe is handled by xcat which uses dhcpd for this. It seems
to be working fine :)

Regards

Em qua, 20 de jun de 2018 10:59, Laine Stump <laine at redhat.com> escreveu:

> On 06/18/2018 01:00 PM, Daniel. wrote:
> > Thanks for the reply Laine. My problem is that dnsmasq is masking
> > dhcpd, xCAT uses dhcpd for PXE stuff. If dnsmasq answer DHCP requests
> > the PXE boot won' t work. I want to see the logs for ensuring the
> > dnsmasq is not masking dhcpd.
>
> The dnsmasq run by libvirtd only listens on bridges that libvirt itself
> creates for libvirt virtual networks. If the PXE boot you're talking
> about is happening on a different interface, then libvirt's dnsmasq will
> not be messing with it.
>
> If, on the other hand, you want to do PXE boot on the virtual networks
> created by libvirt, then you can either 1) disable libvirt's dhcp on
> that network by removing the <dhcp> section from the network definition
> and restarting it, or 2) read in the libvirt virtual network
> documentation on how to set it up to support PXE boot via dnsmasq (and
> don't configure your dhcpd to listen on that interface).
>
> >
> > Regards,
> >
> > 2018-06-18 11:39 GMT-03:00 Laine Stump <laine at redhat.com>:
> >> On 06/18/2018 09:16 AM, Daniel. wrote:
> >>> Cool, thanks!! Does it have logs?
> >>
> >> Whatever dnsmasq chooses to log, and wherever it chooses to log it. (I
> >> actually looked once to see if there was a way of reducing the amount of
> >> logging, and didn't find much of anything useful.)
> >>
> >> If you were planning to learn the current IP address of a particular
> >> guest's interface by looking at the logs, you can instead use the virsh
> >> domifaddr to to that.
> >>
> >>>
> >>>
> >>> Cheers
> >>>
> >>> Em 18/06/2018 12:55 AM, "Laine Stump" <laine at redhat.com
> >>> <mailto:laine at redhat.com>> escreveu:
> >>>
> >>>     On 06/15/2018 06:49 PM, Daniel. wrote:
> >>>     > Hi everybody,
> >>>     >
> >>>     > I'm using libvirt together with xCAT, on the same host, for
> testing
> >>>     > purposes. xCAT install and manages dhcpd. How libvirt interacts
> with
> >>>     > dhcpd? And if doens't how does the dhcp server of libvirt works,
> plus
> >>>     > where I can find information on how to troubleshot it?
> >>>
> >>>     libvirt doesn't use dhcpd. It runs a separate instance of dnsmasq
> for
> >>>     each virtual network that is defined within libvirt. Each instance
> >>>     listens *only* on the bridge device that was created by libvirt
> for that
> >>>     network. IIfi dhcpd has an option that tells it to listen on all
> >>>     interfaces (or to automatically start listening on any new
> interface
> >>>     that is created), you should disable that option so that it doesn't
> >>>     attempt to listen for dhcp requests on the bridges created by
> libvirt.
> >>>
> >>>
> >>
> >
> >
> >
>
>
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