一般來說L3中就兩個設置，可不要小看interface_drive，設置錯就會導致問題
interface_driver = neutron.agent.linux.interface.BridgeInterfaceDriver接口驅動設置
這個設置錯誤，啓動服務是不會報錯的，但是服務真的啓動了嗎？？
啓動服務：看似沒有問題
[root@controller ~]# systemctl restart neutron-l3-agent.service[root@controller ~]# systemctl status neutron-l3-agent.service
● neutron-l3-agent.service - OpenStack Neutron Layer 3 Agent
Loaded: loaded (/usr/lib/systemd/system/neutron-l3-agent.service; enabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Thu 2017-11-16 11:40:43 EST; 20s ago
Process: 17496 ExecStart=/usr/bin/neutron-l3-agent --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/l3_agent --config-file /etc/neutron/neutron.conf --config-dir /etc/neutron/conf.d/common --config-dir /etc/neutron/conf.d/neutron-l3-agent --log-file /var/log/neutron/l3-agent.log (code=exited, status=1/FAILURE)
Main PID: 17496 (code=exited, status=1/FAILURE)
Nov 16 11:40:41 controller systemd[1]: Started OpenStack Neutron Layer 3 Agent.
Nov 16 11:40:41 controller systemd[1]: Starting OpenStack Neutron Layer 3 Agent...
Nov 16 11:40:42 controller neutron-l3-agent[17496]: Guru mediation now registers SIGUSR1 and SIGUSR2 by default for backward compatibility. SIGUSR1 will no longer be registered in a future rele...rate reports.
Nov 16 11:40:42 controller neutron-l3-agent[17496]: Option "verbose" from group "DEFAULT" is deprecated for removal. Its value may be silently ignored in the future.
Nov 16 11:40:43 controller neutron-l3-agent[17496]: Option "notification_driver" from group "DEFAULT" is deprecated. Use option "driver" from group "oslo_messaging_notifications".
Nov 16 11:40:43 controller systemd[1]: neutron-l3-agent.service: main process exited, code=exited, status=1/FAILURE
Nov 16 11:40:43 controller systemd[1]: Unit neutron-l3-agent.service entered failed state.
Nov 16 11:40:43 controller systemd[1]: neutron-l3-agent.service failed.
Hint: Some lines were ellipsized, use -l to show in full.
L3服務狀態當然是xxx
[root@controller ~]# neutron agent-list
+--------------------------------------+--------------------+------------+-------------------+-------+----------------+---------------------------+
| id | agent_type | host | availability_zone | alive | admin_state_up | binary |
+--------------------------------------+--------------------+------------+-------------------+-------+----------------+---------------------------+
| 1576ae04-aff3-45af-8a5e-d83f84c78555 | DHCP agent | controller | nova | :-) | True | neutron-dhcp-agent |
| 2a21a914-d1cb-4b37-a8f1-4b295403ac8c | Linux bridge agent | compute | | :-) | True | neutron-linuxbridge-agent |
| 88d5d470-f5d3-41b7-a600-9d7fdcddc930 | Metadata agent | controller | | :-) | True | neutron-metadata-agent |
| db07bd42-504e-4b7c-b5a6-badbcd0547ef | Linux bridge agent | controller | | :-) | True | neutron-linuxbridge-agent |
| e3606dd1-ed63-4f66-b3db-fdeafdf5ffa7 | L3 agent | controller | nova | xxx | True | neutron-l3-agent |
+--------------------------------------+--------------------+------------+-------------------+-------+----------------+---------------------------+
L3服務出現xxx一般來說就是interface_driver = neutron.agent.linux.interface.BridgeInterfaceDriver錯了，另外一個設置允許多種外部網絡也就是 " external_network_bridge = " 並不礙事
