Hello Cam,

The problem you described seems to be similar to the described in https://bugzilla.redhat.com/show_bug.cgi?id=1242227.
The mentioned bug was fixed in one of the recent oVirt builds.

The updated Ovirt code allows to mix networks (regardless of them being VM or non-VM) on a single NIC with the following conditions:

not more than one non-VLAN network in conjunction with any number of VLANs
MTU of the VLAN networks have to be equal to that of a non-VLAN one if such exists

So I'd advise you to update you oVirt to the latest build.

Regards,

Yevgeny

On Tue, Oct 6, 2015 at 2:47 AM, Cam Wright <cwright@cuttingedge.com.au> wrote:

Hi,

I've just started building an oVirt farm as a replacement for our
existing infrastructure and I'm having issues configuring multiple
VLAN bridges with different MTUs.

When I try to add a logical network with a VLAN tag + VM Network + MTU
9000 to a bonded interface on my host with only the ovirtmgmt network
(MTU 1500, default) it throws up an error message and won't let me
continue, error message below:

Cannot setup Networks. The following Logical Networks do not have the
same MTU value: ovirtmgmt(default),
net_bne_vlan10(9000).

Eventually, I will want to add more logical networks with the default
MTU, so setting the ovirtmgmt MTU to 9000 is unfortunately not going
to solve my issue.

This is something I can do in vanilla Linux networking where I set the
802.3ad bond to be MTU 9000 and configure two different bridges off
that interface to 1500 and 9000, however this does not seem to be
possible in the oVirt web interface.

I've dug through the Administration guide and feature requests and
there doesn't seem to be anything there around using different MTU
values for different logical networks.

Has anyone been able to successfully do this? The
/etc/sysconfig/network-scripts and /var/lib/vdsm/persistence/netconf
files seem to get rewritten whenever the vdsm service does anything,
so I'm reluctant to edit them manually.

The hosts were built using the hosted-engine installer on Fedora 22.
The engine is running Fedora 22 also, see below:

[root@bne-ovirtengine01 ~]# cat /etc/redhat-release
Fedora release 22 (Twenty Two)
[root@bne-ovirtengine01 ~]# uname -r
4.0.4-301.fc22.x86_64

oVirt Engine Version: 3.6.0-1.fc22

Any assistance would be appreciated.

Cam Wright | Systems Administrator
CUTTINGEDGE
90 Victoria St, West End, Brisbane, QLD, 4101
T +61 7 3013 6222
E cwright@cuttingedge.com.au | W www.cuttingedge.com.au

/SYD /BNE /MEL /TYO
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