I've got a problem with my network configuration. When I see neutron agents, I obtain this (not alives):

+--------------------------------------+--------------------+--------------------+-------+----------------+
| id     | agent_type         | host               | alive | admin_state_up |
+--------------------------------------+--------------------+--------------------+-------+----------------+
| 134c047a-8cb5-4120-97ce-ad73fe6c5631 | Metadata agent     | ubuntupruebas-comp | xxx   | True |
| 782cb953-5fbd-4c8b-8a8d-efbb1bdad0ff | Open vSwitch agent | ubuntupruebas-comp | xxx   | True  |
| 86e64314-c5a5-421e-864b-068c6fe2e69c | DHCP agent         | ubuntupruebas-comp | xxx   | True   |
| 9221940c-2df3-49a2-8f35-8d5bef3a5f3a | Metering agent     | ubuntupruebas-comp | xxx   | True  |
| bc34d84d-a6a9-4dd5-a7f5-34c56478feb0 | L3 agent           | ubuntupruebas-comp | xxx   | True   |
+--------------------------------------+--------------------+--------------------+-------+----------------+

but when I rerun the command, I obtain this:
$ neutron agent-list
+--------------------------------------+--------------------+--------------------+-------+----------------+
| id   | agent_type         | host               | alive | admin_state_up |
+--------------------------------------+--------------------+--------------------+-------+----------------+
| 134c047a-8cb5-4120-97ce-ad73fe6c5631 | Metadata agent     | ubuntupruebas-comp | xxx   | True    |
| 782cb953-5fbd-4c8b-8a8d-efbb1bdad0ff | Open vSwitch agent | ubuntupruebas-comp | :-)   | True   |
| 86e64314-c5a5-421e-864b-068c6fe2e69c | DHCP agent         | ubuntupruebas-comp | :-)   | True     |
| 9221940c-2df3-49a2-8f35-8d5bef3a5f3a | Metering agent     | ubuntupruebas-comp | xxx   | True     |
| bc34d84d-a6a9-4dd5-a7f5-34c56478feb0 | L3 agent           | ubuntupruebas-comp | :-)   | True   |
+--------------------------------------+--------------------+--------------------+-------+----------------+

And later, they die, and so on.

In horizon, the diagram of my network seems down. For example, I set to my br-ext IP 10.0.0.1, and the router that set gateway -> 10.0.0.5, and it's always down but I can do a "ping" to it.

I'm using Ubuntu14.04 with Open-vswitch

Any suggestions?