Upgrade of openvswitch-2.4.0-1.el7 makes ip disappears on undercloud. With update from RHEL 7.2 to 7.3 we have to handle the case when we loose ip on br-ctlplane during rpm post scrtipt of openvswitch package.
the important point to note here is that this is for the *undercloud*. For the overcloud we are tracking the fix at BZ 1364540
There's a doc bug to update the procedure. Need to stop the openvswitch service before running "openstack undercloud upgrade" https://bugzilla.redhat.com/show_bug.cgi?id=1395766