Description:
===========
when ODL is disconnected, deleted the configuration then after reconnection of ODL still entry
for interfaces remains in ODL data store, due to this stale flows will remains on DPNs.

Test Scenario:
=============

Step1:
openstack network create net90
openstack subnet create --network net90 --subnet-range 90.10.10.0/24 subnet90
openstack server create VM21 --flavor myhuge --image cirros-0.3.4-x86_64-uec --network net90 --availability-zone nova:controller-suneel
openstack server create VM22 --flavor myhuge --image cirros-0.3.4-x86_64-uec --network net90 --availability-zone nova:controller-suneel

Step2: Disconnect the ODL (i.e logout from karaf)

Step3: Delete the above created configuration
openstack server delete VM21 VM22
openstack network delete net90

Step4: Reconnect the ODL (i.e start the karaf) and verify the sync of openstack data with ODL

Results:
=======

• Stale Entry noticed for interfaces in ODL
• No stale entry seen for neutron ports, subnet and network

Logs:
=====
Karaf log (Trace enabled for trace "org.opendaylight.netvirt.neutronvpn")
Openstack logs
ODL Data Store log for Interfaces (After delete of configuration)