Neutorn-server service fails to start on a controller

Issue

• Can not login to Horizon dashboard as it is throwing error: "GATEWAY TIME OUT"
• Neutron-server service fails to start

[root@overcloud-controller-2 heat-admin]# systemctl -l status neutron-server.service
neutron-server.service - OpenStack Neutron Server
   Loaded: loaded (/usr/lib/systemd/system/neutron-server.service; disabled)
   Active: failed (Result: exit-code) since Tue 2016-03-08 19:43:41 GMT; 51min ago
 Main PID: 31049 (code=exited, status=1/FAILURE)
   CGroup: /system.slice/neutron-server.service
           ââ19570 /usr/bin/python2 /usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/server --config-file /etc/neutron/neutron.conf --config-file /etc/neutron/plugin.ini --config-dir /etc/neutron/conf.d/common --config-dir /etc/neutron/conf.d/neutron-server --log-file /var/log/neutron/server.log

Mar 08 19:43:41 overcloud-controller-2.localdomain neutron-server[31049]: ERROR: Could not bind to 10.239.176.13:9696 after trying for 30 seconds
Mar 08 19:43:41 overcloud-controller-2.localdomain systemd[1]: neutron-server.service: main process exited, code=exited, status=1/FAILURE
Mar 08 19:43:41 overcloud-controller-2.localdomain systemd[1]: Failed to start OpenStack Neutron Server.
Mar 08 19:43:41 overcloud-controller-2.localdomain systemd[1]: Unit neutron-server.service entered failed state.
Mar 08 19:43:42 overcloud-controller-2.localdomain systemd[1]: Stopped OpenStack Neutron Server.