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

[NUNIN Roberto]

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.

>
> >
> > 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.


>
> Which bond mode are you using? I recently seen
>
>     https://bugzilla.redhat.com/show_bug.cgi?id=1230638#c22
>
> closed as duplicate of
>
>     Bug 1094842 - Bonding modes 0, 5 and 6 should be avoided for VM
>     networks

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