[ovirt-users] Ovirt causing strange network issues?

[Derek Atkins]

I'm sorry. What is STP?
And how do I turn that off?

-derek
Sent using my mobile device. Please excuse any typos.



On October 2, 2017 7:41:15 PM Colin Coe <colin.coe at gmail.com> wrote:

> Hi
>
> We saw something very similar to this a couple of years ago.  In our case,
> it was caused by STP being enabled on our hypervisors.
>
> HTH
>
>
>
> On 3 Oct. 2017 04:56, "Derek Atkins" <derek at ihtfp.com> wrote:
>
>> Hi,
>>
>> I'm at my wits end so I'm tossing this here in the hopes that SOMEONE
>> will be able to help me.
>>
>> tl;dr: Ovirt is doing something on my network that is causing my fiber
>> modem to go from 3-5ms to 300-1000+ms round trip times.  I know it's
>> ovirt because when I unplug ovirt from my network the issue goes away;
>> when I plug it back in, the issue recurs.
>>
>> Long version:
>>
>> I've been running Ovirt 4.0.6 happily on CentOS 7.3 for several months
>> on a single host machine. Indeed, the host had an uptime of 200+ days
>> and was working great until approximately midnight, September 21/22
>> (just over a week ago).  I was on an airplane halfway across the
>> Atlantic at that time, so it wasn't anything I did.
>>
>> My network is configured as:
>>
>>   fiber modem <-> edgerouter <-> switch <-> everything else
>>
>> ovirt is living in the "everything else" area.
>>
>> When I sit with a laptop connected to either the everything else range
>> or even directly connected to the fiber modem, I run 'mtr' and see
>> network times (starting at the fiber modem) that bounce all over the
>> place.  When I unplug ovirt I see consistent 3-5ms times.  Plug it back
>> in, voom, back up to badness.
>>
>> I've spent several hours plugging and unplugging different devices
>> trying to isolate the issue.  The only "device" that has any effect is
>> my ovirt box.
>>
>> I have tried to debug this in several ways, but really the only thing
>> that seems to have helped at all is shutting down all the VMs and the
>> hosted engine.  Once nothing else is running (but the host itself), only
>> then does the network seem to return to normal.
>>
>> I'm really at my wits end on this; I have no idea what is causing this
>> or what might have changed to cause the issue right at that time.  I
>> also can't imagine what ovirt is doing over the network that could cause
>> the modem, two physical hops away, to lose its mind in this way.  But my
>> experiementation is definitely showing a direct correlation.
>>
>> Help!!
>>
>> -derek
>>
>> --
>>        Derek Atkins                 617-623-3745 <(617)%20623-3745>
>>        derek at ihtfp.com             www.ihtfp.com
>>        Computer and Internet Security Consultant
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>> Users at ovirt.org
>> http://lists.ovirt.org/mailman/listinfo/users
>>
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