[ovirt-users] Problemas with ovirtmgmt network used to connect VMs

[FERNANDO FREDIANI]

Hello.

Despite I didn't get any feedback on this topic anymore I just wanted to 
let people know that since I moved the VM to another oVirt Cluster 
running oVirt-Node-NG and Kernel 3.10 the problem stopped happening. 
Although I still don't know the cause of it I suspect it may have to do 
with the kernel that other Host (hypervsior) is running (4.12) as that 
is the only once running disk kernel for an specific reason.
To support this suspicious in the past I had another Hypervisor also 
running kernel 4.12 and a VM that does that same job had the same issue. 
After I have rebooted the Hypervisor back to default kernel (3.10) the 
problem didn't happen anymore.

If anyone ever faces this or anything similar please let me know as I am 
always interested to find out the root of this issue.

Regards
Fernando


On 28/07/2017 15:01, FERNANDO FREDIANI wrote:
>
> Hello Edwardh and all.
>
> I keep getting these disconnects, were you able to find anything about 
> to suggest changing ?
>
> As I mentioned this machine different from the others where it never 
> happened uses the ovirtmgmt network as VM network and has kernel 4.12 
> instead of the default 3.10 from CentOS 7.3. It seems a particular 
> situation that is triggering this behavior but could not gather any 
> hint yet.
>
> I have tried to run a regular arping to force the bridge always learn 
> the VMs MAC address but it doesn't seem to work and every in a while 
> the bridge 'forgets' that particular VM mac address.
> I have also even rebuilt the VM completely changing its operating 
> system from Ubuntu 16.04 to CentOS 7.3 and the same problem happened.
>
> Fernando
>
>
> On 24/07/2017 18:20, FERNANDO FREDIANI wrote:
>>
>> Hello Edward, this happened again today and I was able to check more 
>> details.
>>
>> So:
>>
>> - The VM stopped passing any network traffic.
>> - Checking 'brctl showmacs ovirtmgmt' it showed the VM's mac address 
>> missing.
>> - I then went to oVirt Engine, under VM's 'Network Interfaces' tab, 
>> clicked Edit and changed the Link State to Down then to Up and it 
>> recovered its connectivity.
>> - Another 'brctl showmacs ovirtmgmt' showed the VM's mac address 
>> learned again by the bridge.
>>
>> This Node server has the particularity of sharing the ovirtmgmt with 
>> VMs. Could it possibly be the cause of the issue in any way ?
>>
>> Thanks
>> Fernando
>>
>>
>> On 24/07/2017 09:47, FERNANDO FREDIANI wrote:
>>>
>>> Not tried this yet Edwardh, but will do at next time it happens. THe 
>>> source mac address should be the mac as the VM. I don't see any 
>>> reason for it to change from within the VM ou outside.
>>>
>>> What type of things would make the bridge stop learning a given VM 
>>> mac address ?
>>>
>>> Fernando
>>>
>>>
>>> On 23/07/2017 07:51, Edward Haas wrote:
>>>> Have you tried to use tcpdump at the VM vNIC to examine if there is 
>>>> traffic trying to get out from there? And with what source mac address?
>>>>
>>>> Thanks,
>>>> Edy,
>>>>
>>>> On Fri, Jul 21, 2017 at 5:36 PM, FERNANDO FREDIANI 
>>>> <fernando.frediani at upx.com <mailto:fernando.frediani at upx.com>> wrote:
>>>>
>>>>     Has anyone had problem when using the ovirtmgmt bridge to
>>>>     connect VMs ?
>>>>
>>>>     I am still facing a bizarre problem where some VMs connected to
>>>>     this bridge stop passing traffic. Checking the problem further
>>>>     I see its mac address stops being learned by the bridge and the
>>>>     problem is resolved only with a VM reboot.
>>>>
>>>>     When I last saw the problem I run brctl showmacs ovirtmgmt and
>>>>     it shows me the VM's mac adress with agening timer 200.19.
>>>>     After the VM reboot I see the same mac with agening timer 0.00.
>>>>     I don't see it in another environment where the ovirtmgmt is
>>>>     not used for VMs.
>>>>
>>>>     Does anyone have any clue about this type of behavior ?
>>>>
>>>>     Fernando
>>>>     _______________________________________________
>>>>     Users mailing list
>>>>     Users at ovirt.org <mailto:Users at ovirt.org>
>>>>     http://lists.ovirt.org/mailman/listinfo/users
>>>>     <http://lists.ovirt.org/mailman/listinfo/users>
>>>>
>>>>
>>>
>>
>

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