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

[NUNIN Roberto]

Da: users-bounces at ovirt.org [mailto:users-bounces at ovirt.org] Per conto di Jorick Astrego
Inviato: mercoledì 29 luglio 2015 14:26
A: users at ovirt.org
Oggetto: Re: [ovirt-users] R: R: R: R: R: R: R: R: PXE boot of a VM on vdsm don't read DHCP offer



On 07/29/2015 12:12 PM, NUNIN Roberto wrote:
>> -----Messaggio originale-----
>> Da: Michael S. Tsirkin [mailto:mst at redhat.com<mailto:redhat.com>]
>> Inviato: mercoledì 29 luglio 2015 12:03
>> A: NUNIN Roberto
>> Cc: Fabian Deutsch; users at ovirt.org<mailto:ovirt.org>
>> Oggetto: Re: R: [ovirt-users] R: R: R: R: R: R: PXE boot of a VM on vdsm don't
>> read DHCP offer
>>
>> On Wed, Jul 29, 2015 at 12:00:38PM +0200, NUNIN Roberto wrote:
>>>> -----Messaggio originale-----
>>>> Da: users-bounces at ovirt.org<mailto:ovirt.org> [mailto:users-bounces at ovirt.org<mailto:ovirt.org>] Per conto
>> di
>>>> Michael S. Tsirkin
>>>> Inviato: giovedì 9 luglio 2015 15:15
>>>> A: Fabian Deutsch
>>>> Cc: users at ovirt.org<mailto:ovirt.org>
>>>> Oggetto: Re: [ovirt-users] R: R: R: R: R: R: PXE boot of a VM on vdsm don't
>> read
>>>> DHCP offer
>>>>
>>>> On Thu, Jul 09, 2015 at 08:57:50AM -0400, Fabian Deutsch wrote:
>>>>> ----- Original Message -----
>>>>>> On Wed, Jul 08, 2015 at 09:11:42AM +0300, Michael S. Tsirkin wrote:
>>>>>>> On Tue, Jul 07, 2015 at 05:13:28PM +0100, Dan Kenigsberg wrote:
>>>>>>>> On Tue, Jul 07, 2015 at 10:14:54AM +0200, NUNIN Roberto wrote:
>>>>>>>>>> On Mon, Jul 06, 2015 at 10:33:59AM +0200, NUNIN Roberto
>> wrote:
>>>>>>>>>>> Hi Dan
>>>>>>>>>>>
>>>>>>>>>>> Sorry for question: what do you mean for interface vnetxxxx ?
>>>>>>>>>>> Currently our path is :
>>>>>>>>>>> eno1 - eno2  ---- bond0 ----- bond.3500 (VLAN) ------ bridge -----
>>>>>>>>>>> vm.
>>>>>>>>>>>
>>>>>>>>>>> Which one of these ?
>>>>>>>>>>> Moreover, reading Fabian statements about bonding limits,
>>>> today I
>>>>>>>>>>> can try
>>>>>>>>>> to switch to a config without bonding.
>>>>>>>>>>
>>>>>>>>>> "vm" is a complicated term.
>>>>>>>>>>
>>>>>>>>>> `brctl show` would not show you a "vm" connected to a bridge.
>>>> When
>>>>>>>>>> you
>>>>>>>>>> WOULD see is a vnet888 tap device. The "other side" of this
>> device
>>>> is
>>>>>>>>>> held by qemu, which implement the VM.
>>>>>>>>> Ok, understood and found it, vnet2
>>>>>>>>>
>>>>>>>>>> I'm asking if the dhcp offer has reached that tap device.
>>>>>>>>> No, the DHCP offer packet do not reach the vnet2 interface, I can
>> see
>>>>>>>>> only DHCP DISCOVER.
>>>>>>>> Ok, so it seems that we have a problem in the host bridging.
>>>>>>>>
>>>>>>>> Is it the latest kernel-3.10.0-229.7.2.el7.x86_64 ?
>>>>>>>>
>>>>>>>> Michael, a DHCP DISCOVER is sent out of a just-booted guest, and
>>>> OFFER
>>>>>>>> returns to the bridge, but is not propagated to the tap device.
>>>>>>>> Can you suggest how to debug this further?
>>>>>>> Dump packets including the ethernet headers.
>>>>>>> Likely something interfered with them so the eth address is wrong.
>>>>>>>
>>>>>>> Since bonding does this sometimes, this is the most likely culprit.
>>>>>> We've ruled this out already - Roberto reproduces the issue without a
>>>>>> bond.
>>>>> To me this looks like either a regression in the host side bridging. But
>> otoh it
>>>> doesn't look
>>>>> like it's happening always, because otherwise I'd expect more noise
>> around
>>>> this issue.
>>>>> - fabian
>>>> Hard to say. E.g. forwarding delay would do this for a while.
>>>> If eth address of the packets is okay, poke at the fbd, maybe there's
>>>> something wrong there. Maybe stp is detecting a loop - try checking that.
>>> Someone is checking this ?
>>> In tested config SPT was off.
>> Then maybe you have a loop :)
> That was already checked, the MAC was unique in the VLAN.
>
> RN
>

>Did you also try a reboot of the VM? We have the same issue with foreman
>and both Libvirt and oVirt. On second boot PXE boots properly from DHCP.

Yes tried more than one time the reboot, without changes.
RN


>Haven't had the time to investigate yet so we're using mostly image
>based provisioning on oVirt at the moment.





Met vriendelijke groet, With kind regards,

Jorick Astrego

Netbulae Virtualization Experts
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