What happens when a vm gets created by using OVN

When a new VM gets created successfully, the following happens: 

1. a port entry gets created, the port should have mac and IP address. use "ovn-nbctl show" command to verify. 
2. a Port_Binding entry gets created, use "ovn-sbctl show" and "ovsdb-client dump" against the southbound database to verify. 
3. a tap Port gets created, use "ovs-vsctl show" command to verify on the compute node where the VM was hosted. The tap port should be part of the br-int bridge.
4. From the namespace, one should be able to ping the IP address of that new VM. Regardless which compute node the ping happens, the ping should be successful.

When a network gets created:

1. A logical switch will be created with a name like this "neutron-<neutron network id>" 
2. In that switch, first few ports such as .2, .3 will be used for dhcp server IPs. If there are two dhcp servers per network, then .2 and .3 will be used, however ip address .1 will be reserved for the gateway which will be used when the network gets hooked up with another network.
3. Traffic between provider network bridge and br-int are isolated via tunnel key (id).

normally northbound database is at port 6641, dump the database content using this command:
       ovsdb-client dump tcp:127.0.0.1:6641

normally southbound database is at port 6642, dump the database content using this command:
       ovsdb-client dump tcp:127.0.0.1:6642