I have 3 node setup , each node having 2 NICs & I am not able to ping/ssh to instances (security group rules are created)

• controller private ip 10.211.20.50/ public ip XX.XXX.111.31
• network private ip 10.211.20.51/ public ip XX.XXX.111.32
• compute private ip 10.211.20.52/ public ip XX.XXX.111.33

On compute node 'openvswitch-agent.log' shows an error

ERROR [quantum.agent.linux.ovs_lib] Unable to execute ['ovs-vsctl', '--timeout=2', 'add-port', 'br-tun', 'gre-3']. Exception:
Command: ['sudo', 'quantum-rootwrap', '/etc/quantum/rootwrap.conf', 'ovs-vsctl', '--timeout=2', 'add-port', 'br-tun', 'gre-3']
Exit code: 1
Stdout: ''
Stderr: 'ovs-vsctl: cannot create a port named gre-3 because a port named gre-3 already exists on bridge br-tun\n'

Here are the details from database

mysql> select * from ovs_tunnel_endpoints;
+--------------+----+
| ip_address   | id |
+--------------+----+
| 10.211.20.51 |  3 |
| 10.211.20.52 |  2 |
+--------------+----+
2 rows in set (0.00 sec)

mysql> select * from ovs_network_bindings;
+--------------------------------------+--------------+------------------+-----------------+
| network_id                           | network_type | physical_network | segmentation_id |
+--------------------------------------+--------------+------------------+-----------------+
| c861b1ba-6e94-4827-bacf-e6b5da6bf435 | gre          | NULL             |               1 |
+--------------------------------------+--------------+------------------+-----------------+
1 row in set (0.00 sec)

mysql> select * from ovs_tunnel_allocations where allocated != 0;
+-----------+-----------+  
| tunnel_id | allocated |
+-----------+-----------+
|         1 |         1 |
+-----------+-----------+
1 row in set (0.00 sec)

Please let me know what am i missing.