The other issue is highlighted by:

2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent [req-7422fadb-d790-4825-aeeb-e6bed6eee188 - - - - -] Error in agent loop. Devices info: {'current': set(['tap7e4f7c40-86', 'tap9a4ed18e-82', 'tap34eb30e9-ef', 'tap3beb1db4-6d']), 'timestamps': {'tap7e4f7c40-86': 1473371191.1141872, 'tap9a4ed18e-82': 1473371191.1141872, 'tap34eb30e9-ef': 1473371191.1141872, 'tap3beb1db4-6d': None}, 'removed': set([]), 'added': set(['tap7e4f7c40-86', 'tap9a4ed18e-82', 'tap3beb1db4-6d']), 'updated': set([u'tap7e4f7c40-86', u'tap9a4ed18e-82'])}
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent Traceback (most recent call last):
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent   File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/drivers/agent/_common_agent.py", line 450, in daemon_loop
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent     sync = self.process_network_devices(device_info)
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent   File "/usr/lib/python2.7/dist-packages/osprofiler/profiler.py", line 154, in wrapper
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent     return f(*args, **kwargs)
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent   File "/usr/lib/python2.7/dist-packages/neutron/plugins/ml2/drivers/agent/_common_agent.py", line 200, in process_network_devices
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent     device_info.get('updated'))
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent   File "/usr/lib/python2.7/dist-packages/neutron/agent/securitygroups_rpc.py", line 265, in setup_port_filters
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent     self.prepare_devices_filter(new_devices)
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent   File "/usr/lib/python2.7/dist-packages/neutron/agent/securitygroups_rpc.py", line 130, in decorated_function
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent     *args, **kwargs)
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent   File "/usr/lib/python2.7/dist-packages/neutron/agent/securitygroups_rpc.py", line 138, in prepare_devices_filter
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent     self._apply_port_filter(device_ids)
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent   File "/usr/lib/python2.7/dist-packages/neutron/agent/securitygroups_rpc.py", line 163, in _apply_port_filter
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent     self.firewall.prepare_port_filter(device)
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent   File "/usr/lib/python2.7/dist-packages/neutron/agent/linux/iptables_firewall.py", line 170, in prepare_port_filter
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent     self._enable_netfilter_for_bridges()
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent   File "/usr/lib/python2.7/dist-packages/neutron/agent/linux/iptables_firewall.py", line 114, in _enable_netfilter_for_bridges
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent     run_as_root=True)
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent   File "/usr/lib/python2.7/dist-packages/neutron/agent/linux/utils.py", line 138, in execute
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent     raise RuntimeError(msg)
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent RuntimeError: Exit code: 255; Stdin: ; Stdout: ; Stderr: sysctl: cannot stat /proc/sys/net/bridge/bridge-nf-call-arptables: No such file or directory
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent 
2016-09-08 21:46:45.383 26458 ERROR neutron.plugins.ml2.drivers.agent._common_agent