[ovirt-users] R: R: R: R: PXE boot of a VM on vdsm don't read DHCP offer

[Dan Kenigsberg]

On Fri, Jul 03, 2015 at 04:32:50PM +0200, NUNIN Roberto wrote:
> Thanks for answering. My considerations below.
> 
> BR,
> 
> ROberto
> > -----Messaggio originale-----
> > Da: Dan Kenigsberg [mailto:danken at redhat.com]
> > Inviato: venerdì 3 luglio 2015 12:31
> > A: NUNIN Roberto
> > Cc: users at ovirt.org; ibarkan at redhat.com
> > Oggetto: Re: R: R: [ovirt-users] R: PXE boot of a VM on vdsm don't read
> > DHCP offer
> >
> > On Fri, Jul 03, 2015 at 10:51:52AM +0200, NUNIN Roberto wrote:
> > > Hi Dan, guys
> > >
> > > Sorry for very late follow-up, but we had a lot of other topics to fix just
> > before to go back on this one.
> > >
> > > We have tried another approach just to check if the kernel of the vdsm iso
> > image used to install the host could create the problem I've reported to the
> > list.
> > >
> > > Now we have reinstalled the same hardware with latest CentOS 7.1, fully
> > updated.
> > > Installed vdsm, then joined the oVirt cluster.
> > >
> > > Well, we are observing the same behavior as before.
> > > No DHCP offer is reaching the booting VM, and:
> > >
> > > brctl showmacs <bridge_if> show us the booting vm mac-address
> > > tcpdump -I <bridge_if> show us the dhcp offer coming from dhcp server.
> >
> > The offer should be replicated to the tap device (vnetXXX). I assume
> > that it does not?
> 
> The DHCP offer package coming from DHCP server flows thru the bond0
> device (tagged), the  VLAN device (tagged) and the bridge interface
> (not anymore tagged, correct), so it seems that the path back is
> complete, considering that brctl showmacs shows the vm mac and If we
> put a static IP into the vm nic, it works correctly.

Let's try to trace the offer for one more link. If it does not get to
the tap device vnetXXX - it is clearly a host-side issue. Maybe a bridge
module bug. If you spot the offer on the tap, the it becomes more likely
that the issue is in qemu or elsewere in the virt stack.

I would appreciate your assistence!

> 
> >
> > >
> > > We have also tried to remove ANY firewall rule.
> > >
> > > It isn't a PXE issue (gPXE 0.9.7) but only a DHCP process issue. Infact, if we
> > install a vm manually and assign a static IP, it works fine.
> > > If we switch to dhcp, the vm don't get the dynamic one.
> > > In this case, tcpdump on vm shows only the DHCP discovery, not the DHCP
> > offer.
> > >
> > > Any further suggestion/hint ?
> 
> We have mode 4, but already checked active/backup, mode 2, without changes.
> 

Thanks, so it's not that bonding issue.

Regards,
Dan.