neutron.service啓動不成功一般有三種錯誤可能
前兩種是啓動時，長時間卡主無反應，第三種爲啓動失敗報錯
1.neutron.service配置文件中core_plugin = xxx 的設置錯誤，錯誤和沒有寫都會導致啓動時卡主
第一種日誌無明顯報錯
2.neutron.service配置文件中[oslo_messaging_rabbit]下rabbit_password=xxx的密碼設置錯誤，此項錯誤會導致啓動時卡主
第二種報錯AMQP5672
3.如果你沒有設置網絡服務初始化腳本的超鏈接將導致neutron.service啓動失敗
[root@controller ~]# systemctl restart neutron-server.service
Job for neutron-server.service failed because the control process exited with error code. See "systemctl status neutron-server.service" and "journalctl -xe" for details.
設置後啓動成功
[root@controller ~]# ln -s /etc/neutron/plugins/ml2/ml2_conf.ini /etc/neutron/plugin.ini
[root@controller ~]# systemctl restart neutron-server.service
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注意：不只是neutron.service寫錯了會導致失敗
如果neutron-linuxbridge-agent.service配置文件中[ml2]配置下tenant_network_types = vxlan寫錯了也會導致neutron.service啓動失敗。
有一個神奇的現象就是，上述那個寫錯了，neutron-linuxbridge-agent.service啓動居然是成功，反而是neutron.service的報錯.....這就很氣
[root@controller ~]# systemctl restart neutron-server.service
Job for neutron-server.service failed because the control process exited with error code. See "systemctl status neutron-server.service" and "journalctl -xe" for details.
[root@controller ~]# systemctl restart neutron-linuxbridge-agent.service
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有一種沒有報錯的情況需要注意[keystone_authtoken]下密碼錯誤，這是會啓動成功的，但是在neutron agent-list中會報錯
503 Service Unavailable
The server is currently unavailable. Please try again at a later time.
Neutron server returns request_ids: ['req-2c1666fe-e70f-45e2-b5fd-98e154050f74']
503的報錯大多是keystone認證問題
