Hi Alan,

If I understand you correctly, you try to add a new VM-VLANed network (sandbox)
to interface em1 that already has another VM network (ovirtmgmt).

If so, this operation is not permited. You can't attach VM-VLANed network and
VM-nonVLANed network to same interface.

Good to know. I'll start working on another solution that might work once I get around the blocking bug (more on this in response to Roy shortly). Is there a way to convert the ovirtmgmt network to VLAN'd?

Also, while I have your attention, I expect I will have to enable each VLAN on each host's port of the connected switch, which means I have to set each port with multiple VLANs to trunk mode. Is that right?

To be sure that this is a case, I need to know your vdsm version
and vdsm log will be good as well

There is nothing in the log with that time stamp (as Roy has observed, it is not getting that far), but here are the versions just FYI:

[root@cloudhost01 ~]# rpm -qa | fgrep vdsm

vdsm-python-4.10.0-0.44.14.el6.x86_64

vdsm-xmlrpc-4.10.0-0.44.14.el6.noarch

vdsm-4.10.0-0.44.14.el6.x86_64

vdsm-cli-4.10.0-0.44.14.el6.noarch

vdsm-gluster-4.10.0-0.44.14.el6.noarch