Cannot boot nova instance, neutron fails with `Failed to bind port` in Red Hat OpenStack Platform

Issue

Cannot boot nova instance, neutron fails with Failed to bind port in Red Hat OpenStack Platform

2017-08-11 15:06:20.315 44831 INFO neutron.plugins.ml2.plugin [req-cc150032-8e70-459b-86e4-2387ece27a7a 76961e1802c34cdd8f0a79ef47c2b79a 13a1a02e824c411d8682a08784c797a0 - - -] Attempt 7 to bind port 5b4ff276-fcc0-416d-8272-0f95aded7f42
2017-08-11 15:06:20.326 44831 DEBUG neutron.plugins.ml2.managers [req-cc150032-8e70-459b-86e4-2387ece27a7a 76961e1802c34cdd8f0a79ef47c2b79a 13a1a02e824c411d8682a08784c797a0 - - -] Attempting to bind port 5b4ff276-fcc0-416d-8272-0f95aded7f42 on host compute0 for vnic_type normal with profile  bind_port /usr/lib/python2.7/site-packages/neutron/plugins/ml2/managers.py:726
2017-08-11 15:06:20.326 44831 DEBUG neutron.plugins.ml2.managers [req-cc150032-8e70-459b-86e4-2387ece27a7a 76961e1802c34cdd8f0a79ef47c2b79a 13a1a02e824c411d8682a08784c797a0 - - -] Attempting to bind port 5b4ff276-fcc0-416d-8272-0f95aded7f42 on host compute0 at level 0 using segments [{'segmentation_id': None, 'physical_network': u'external_network', 'id': u'e746e7d1-2d09-4da1-acd6-ed38d15556ad', 'network_type': u'flat'}] _bind_port_level /usr/lib/python2.7/site-packages/neutron/plugins/ml2/managers.py:747
2017-08-11 15:06:20.326 44831 DEBUG neutron.plugins.ml2.drivers.mech_agent [req-cc150032-8e70-459b-86e4-2387ece27a7a 76961e1802c34cdd8f0a79ef47c2b79a 13a1a02e824c411d8682a08784c797a0 - - -] Attempting to bind port 5b4ff276-fcc0-416d-8272-0f95aded7f42 on network bba1a41c-887b-40c4-a5c7-ab600ce34ee8 bind_port /usr/lib/python2.7/site-packages/neutron/plugins/ml2/drivers/mech_agent.py:89
2017-08-11 15:06:20.331 44831 ERROR neutron.plugins.ml2.managers [req-cc150032-8e70-459b-86e4-2387ece27a7a 76961e1802c34cdd8f0a79ef47c2b79a 13a1a02e824c411d8682a08784c797a0 - - -] Failed to bind port 5b4ff276-fcc0-416d-8272-0f95aded7f42 on host compute0 for vnic_type normal using segments [{'segmentation_id': None, 'physical_network': u'external_network', 'id': u'e746e7d1-2d09-4da1-acd6-ed38d15556ad', 'network_type': u'flat'}]
2017-08-11 15:06:20.331 44831 INFO neutron.plugins.ml2.plugin [req-cc150032-8e70-459b-86e4-2387ece27a7a