Comment 4 for bug 1798588

openvswitch-agent.log
ip and the hostname are replaced, just to keep it a bit confidential.
Here is the step i reproduce the problem
- at 14:07
  i run step 2
  #!/bin/bash

  /bin/ovs-vsctl del-br br-int
  /bin/ovs-vsctl del-br br-bond0
  /bin/ovs-vsctl add-br br-int
  /bin/ovs-vsctl add-br br-bond0
  /bin/ovs-vsctl --may-exist add-bond br-bond0 bond0 eno5 eno6 bond_mode=active-backup

  and reboot the machine.
- at 14:09:18 the machine is booted and pingible
- at 14:11:01 i reboot the machine again (without running step 2)
- at 14:13:xx the machine is booted and network is not available any more.

comparing between the 2 scenario that i tested, in the openvswitch-agent.log the only different is this:
DEBUG ovsdbapp.backend.ovs_idl.transaction [-] Transaction caused no change do_commit /usr/lib/python2.7/site-packages/ovsdbapp/backend/ovs_idl/transaction.py:121

it seems that when the bridge br-bond0 exist neutron-openvswitch-agent decide not to do anything to the bridge and the network broke from there. But if the br-bond0 is delete and on start up neutron-openvswitch-agent decide to do something and the network start work.
The problem seems to point to Openvswitch it-self but when i test disable neutron-openvswitch-agent service completely, the network never break again. So it doesn't seem to be openvswitch problem. I'm running out of ideas for where to look next too.

On the side node, if i run the step 2 and just restart the network server (systemctl restart network), it fix the problem as well.